Patent Publication Number: US-2023139533-A1

Title: Optical sensor including nanophotonic microlens array and electronic device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0149107, filed on Nov. 2, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     Example embodiments of the present disclosure relate to an optical sensor including a nanophotonic microlens array, and an electronic device including the optical sensor. 
     2. Description of Related Art 
     Optical sensors, such as image sensors or spectroscopic sensors, include a sensor substrate including a plurality of pixels, and an optical lens array provided on the sensor substrate and including a plurality of optical lenses covering the pixels. Each of the plurality of pixels may include a plurality of sub-pixels that are separated from each other by a deep trench isolation (DTI) structure, and an autofocusing (AF) technique may be implemented by calculating differences between output signals of the plurality of sub-pixels based on the DTI structure. 
     For example, each of the plurality of pixels included in the sensor substrate may include a total of four sub-pixels arranged in a 2×2 configuration, and one optical lens may cover four sub-pixels included in one pixel. In this case, the four sub-pixels arranged in a 2×2 shape may be separated from each other by a cross-shaped DTI structure. In a process of collecting the incident light on the four sub-pixels by using the optical lens to realize the AF technique, a part of incident light may be collected on the center of the pixel. In this case, the incident light collected on the center of the pixel by the optical lens may be absorbed by the DTI structure provided at the center of the pixel, and thus light loss may occur. 
     In a process of collecting light on the center of the DTI structure and a plurality of sub-pixels separated by the DTI structure to realize the AF technique, it is necessary to design an optical lens array having a structure capable of reducing the amount of incident light collected on the center of the DTI structure so as to minimize light loss. 
     Moreover, as optical sensors, such as image sensors or spectroscopic sensors, and imaging modules are gradually miniaturized, a chief ray angle (CRA) at an edge of an optical sensor is increasing. As the CRA at the edge of the optical sensor increases, the sensitivity of the pixels located at the edge of the optical sensor decreases. This may cause the edge of an image to be dark. In addition, an additional complicated color calculation for compensating for this may impose a burden on an image processing processor and reduce the image processing speed. 
     SUMMARY 
     One or more example embodiments provide an optical sensor including a nanophotonic microlens array having a structure configured to reduce the amount of incident light collected on the center of a deep trench isolation (DTI) structure included in each of a plurality of pixels of a sensor substrate while implementing an autofocusing (AF) technique, and an electronic device including the optical sensor. 
     One or more example embodiments also provide an optical sensor including a nanophotonic microlens array configured to change a traveling direction of incident light, which is incident on an edge of the optical sensor at a high CRA to improve the sensitivity of a sensor substrate including a plurality of pixels, and an electronic device including the optical sensor. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of example embodiments. 
     According to an aspect of an example embodiment, there is provided an optical sensor including a sensor substrate including a plurality of pixels configured to sense incident light, a filter layer provided on the sensor substrate and including a plurality of filters respectively corresponding to the plurality of pixels, the plurality of filters being configured to transmit light of a certain wavelength band, and a nanophotonic microlens array provided on the filter layer and including a plurality of nanophotonic microlenses, each of the plurality of nanophotonic microlenses being configured to focus incident light on a corresponding pixel among the plurality of pixels, wherein each of the plurality of pixels includes a deep trench isolation (DTI) and a plurality of photosensitive cells that are electrically separated from each other by the DTI structure and are two-dimensionally provided in a first direction and a second direction perpendicular to the first direction, each of the plurality of photosensitive cells being configured to independently sense light, wherein each of the plurality of nanophotonic microlenses is formed such that light transmitted through each of the nanophotonic microlenses have a phase profile having a plurality of convex regions and to collect incident light on each of a plurality of regions, which are spaced apart from centers of the plurality of photosensitive cells included in the corresponding pixel, toward the DTI structure, and wherein a portion of incident light transmitted through each of the plurality of nanophotonic microlenses is incident on the DTI structure. 
     Each of the plurality of nanophotonic microlenses may be formed such that a number of convex regions of the phase profile of the light transmitted through each of the plurality of nanophotonic microlenses is equal to a number of photosensitive cells included in the pixel corresponding to each of the plurality of nanophotonic microlenses. 
     Each of the plurality of nanophotonic microlenses may be formed such that light transmitted through a first region corresponding to the DTI structure of each of the plurality of nanophotonic microlenses has a phase profile of a region in which the plurality of convex regions overlap each other, and light transmitted through a second region that is a remaining region other than the first region in each of the plurality of nanophotonic microlenses has a phase profile having the plurality of convex regions. 
     Each of the plurality of nanophotonic microlenses may be formed such that the plurality of convex regions of the phase profile of the light transmitted through each of the plurality of nanophotonic microlenses are symmetrically provided with respect to a first area corresponding to the DTI structure of each of the plurality of nanophotonic microlenses. 
     Each of the plurality of nanophotonic microlenses may be formed such that a phase profile of light transmitted through a third region corresponding to a region between the DTI structure and center points of the plurality of photosensitive cells of each of the plurality of nanophotonic microlenses includes a plurality of maximum points. 
     Each of a plurality of first nanophotonic microlenses, which is provided in a central region of the nanophotonic microlens array, may be formed such that a plurality of convex regions of a phase profile of light transmitted through each of the plurality of first nanophotonic microlenses are symmetrically provided with respect to a first region corresponding to a DTI structure of each of the plurality of first nanophotonic microlenses, and each of a plurality of second nanophotonic microlenses, which is provided in a peripheral region of the nanophotonic microlens array, may be formed such that a phase profile of light transmitted through each of the plurality of second nanophotonic microlenses has an inclined linear phase profile and a convex phase profile mixed with each other. 
     The nanophotonic microlens array may include a plurality of third nanophotonic microlenses provided farther from a central region of the nanophotonic microlens array than the plurality of second nanophotonic microlenses, and each of the plurality of second nanophotonic microlenses may be formed such that a first slope of the linear phase profile of the light transmitted through each of the plurality of second nanophotonic microlenses is less than a second slope of the linear phase profile of light transmitted through each of the plurality of third nanophotonic microlenses. 
     Each of the plurality of nanophotonic microlenses may include a convex lens structure having a plurality of convex portions. 
     A number of convex portions included in each of the plurality of nanophotonic microlenses may be equal to a number of photosensitive cells included in each pixel corresponding to each of the plurality of nanophotonic microlenses. 
     A first region corresponding to the DTI structure of each of the plurality of nanophotonic microlenses may be concave, and the plurality of convex portions are included in a second region that is a remaining region other than the first region of each of the plurality of nanophotonic microlenses. 
     The plurality of convex portions of each of the plurality of nanophotonic microlenses may be symmetrically provided with respect to a first region corresponding to the DTI structure of each of the plurality of nanophotonic microlenses. 
     Each of the plurality of nanophotonic microlenses may be formed such that maximum points of the plurality of convex portions are provided in a third region corresponding to a region between the DTI structure and center points of the plurality of photosensitive cells of each of the plurality of nanophotonic microlenses. 
     Each of the plurality of nanophotonic microlenses may include a single convex lens structure in which a plurality of convex lens-shaped portions partially overlap each other with respect to a center point of the nanophotonic microlens, and the number of the plurality of convex lens-shaped portions may correspond to a number of photosensitive cells included in the pixel corresponding to the nanophotonic microlens. 
     Each of a plurality of first nanophotonic microlenses, which is provided in a central region of the nanophotonic microlens array, may be formed such that a plurality of first convex portions of each of the plurality of first nanophotonic microlenses are symmetrically provided with respect a first region corresponding to the DTI structure of each of the plurality of first nanophotonic microlenses, each of a plurality of 2-1st nanophotonic microlenses, which is provided in a left peripheral region of the nanophotonic microlens array, may be formed such that each of maximum points of a plurality of 2-1st convex portions of each of the plurality of 2-1st nanophotonic microlenses are respectively spaced apart from each of center points of the plurality of photosensitive cells in the first direction, and provided to be closer to a center line of the DTI structure in the first direction than to each of the center points of the plurality of photosensitive cells, and each of a plurality of 2-2nd nanophotonic microlenses, which is provided in a right peripheral region of the nanophotonic microlens array, may be formed such that each of maximum points of a plurality of 2-2nd convex portions of each of the plurality of 2-2nd nanophotonic microlenses are respectively spaced apart from each of the center points of the plurality of photosensitive cells in a direction opposite to the first direction, and are provided to be closer to the center line of the DTI structure in the first direction than to each of the center points of the plurality of photosensitive cells. 
     The plurality of 2-1st convex portions of each of the plurality of 2-1st nanophotonic microlenses and the plurality of 2-2nd convex portions of each of the plurality of 2-2nd nanophotonic microlenses may be symmetrically provided in the second direction with respect to the center line of the DTI structure in the first direction. 
     The nanophotonic microlens array may include a plurality of third nanophotonic microlenses provided farther from a central region of an array of the nanophotonic microlenses than the plurality of 2-1st nanophotonic microlenses and the plurality of 2-2nd nanophotonic microlenses, and a distance by which a plurality of maximum points of a plurality of third convex portions of each of the plurality of third nanophotonic microlenses may be spaced apart from the center points of the plurality of photosensitive cells is greater than a distance by which a plurality of maximum points of a plurality of second convex portions of each of the plurality of 2-1st nanophotonic microlenses and the plurality of 2-2nd nanophotonic microlenses are spaced apart from the plurality of center points of the plurality of photosensitive cells. 
     The plurality of pixels may include a plurality of first pixels each including a plurality of first photosensitive cells configured to sense light of a first wavelength band and a plurality of second pixels each including a plurality of second photosensitive cells configured to sense light of a second wavelength band that is shorter than the first wavelength band, the filter layer may include a plurality of first filters respectively corresponding to the plurality of first pixels and configured to transmit light of the first wavelength band, and a plurality of second filters respectively corresponding to the plurality of second pixels and configured to transmit light of the second wavelength band, and the nanophotonic microlens array may include a plurality of first nanophotonic microlenses corresponding to the plurality of first filters, respectively, and configured to focus light on the plurality of first pixels, and a plurality of second nanophotonic microlenses corresponding to the plurality of second filters, respectively, and configured to focus light on the plurality of second pixels. 
     The plurality of first nanophotonic microlenses and the plurality of second nanophotonic microlenses may be formed such that a plurality of second convex regions included in a phase profile of light transmitted through each of the plurality of second nanophotonic microlenses are more convex than a plurality of first convex regions included in a phase profile of light transmitted through each of the plurality of first nanophotonic microlenses. 
     Each of the plurality of first nanophotonic microlenses may include a first convex lens structure having a plurality of first convex portions, each of the plurality of second nanophotonic microlenses may include a second convex lens structure having a plurality of second convex portions, and the plurality of second convex portions may be formed to be more convex than the plurality of first convex portions. 
     A number of first convex portions included in each of the plurality of first nanophotonic microlenses may be equal to a number of first photosensitive cells included in each of the plurality of first pixels, and a number of second convex portions included in each of the plurality of second nanophotonic microlenses may be equal to a number of second photosensitive cells included in each of the plurality of second pixels. 
     Each of the plurality of first nanophotonic microlenses may be formed such that the plurality of first convex portions included in the first nanophotonic microlens are symmetrically provided with respect a first region corresponding to the DTI structure of the first nanophotonic microlens, and each of the plurality of second nanophotonic microlenses may be formed such that the plurality of second convex portions included in the second nanophotonic microlens are symmetrically provided with respect a second region corresponding to the DTI structure of the second nanophotonic microlens. 
     Each of the plurality of first nanophotonic microlenses and each of the plurality of second nanophotonic microlenses provided in a central region of the nanophotonic microlens array may be formed such that the plurality of first convex portions of each of the plurality of first nanophotonic microlenses are symmetrically provided with respect to a first region corresponding to the DTI structure of each of the plurality of first nanophotonic microlenses, and the plurality of second convex portions of each of the plurality of second nanophotonic microlenses may be symmetrically provided with respect to a second region corresponding to the DTI structure of each of the plurality of second nanophotonic microlenses, each of the plurality of first nanophotonic microlenses and each of the plurality of second nanophotonic microlenses provided in a left peripheral region of the nanophotonic microlens array may be formed such that maximum points of the plurality of first convex portions of each of the plurality of first nanophotonic microlenses and maximum points of the plurality of second convex portions of each of the plurality of second nanophotonic microlenses are respectively spaced apart from each of center points of the plurality of first photosensitive cells included in each of the plurality of first pixels and each of center points of the plurality of second photosensitive cells included in each of the plurality of second pixels in the first direction, and may be provided to be closer to a center line of the DTI structure in the first direction than to each of center points of the plurality of first photosensitive cells and each of center points of the plurality of second photosensitive cells, and each of the plurality of first nanophotonic microlenses and each of the plurality of second nanophotonic microlenses provided in a right peripheral region of the nanophotonic microlens array may be formed such that maximum points of the plurality of first convex portions of each of the plurality of first nanophotonic microlenses and maximum points of the plurality of second convex portions of each of the plurality of second nanophotonic microlenses are respectively spaced apart from each of center points of the plurality of first photosensitive cells included in each of the plurality of first pixels and each of center points of the plurality of second photosensitive cells included in each of the plurality of second pixels in a direction opposite to the first direction, and may be provided to be closer to a center line of the DTI structure in the first direction than to each of center points of the plurality of first photosensitive cells and each of center points of the plurality of second photosensitive cells. 
     The plurality of first convex portions of each of the plurality of first nanophotonic microlenses provided in the left peripheral region and the right peripheral region of the nanophotonic microlens array and the plurality of second convex portions of each of the plurality of second nanophotonic microlenses provided in the left peripheral region and the right peripheral region of the nanophotonic microlens array may be symmetrically provided in the second direction with respect to a center line of the DTI structure. 
     Each of the plurality of nanophotonic microlenses may include a plurality of nanostructures provided such that light transmitted through each of the plurality of nanophotonic microlenses has a phase profile having a plurality of convex regions. 
     Each of the plurality of nanophotonic microlenses may include a sparse area including a plurality of first nanostructures, and a dense area including a plurality of second nanostructure, the dense area may be provided adjacent to the sparse area, and diameters of the plurality of first nanostructures may be less than diameters of the plurality of second nanostructures. 
     The dense area included in each of the plurality of nanophotonic microlenses may include a plurality of sub-dense areas spaced apart from each other by the sparse area. 
     A number of sub-dense areas included in each of the plurality of nanophotonic microlenses may be equal to a number of photosensitive cells included in each pixel corresponding to each of the plurality of nanophotonic microlenses. 
     The sparse area may correspond to a center region and an edge region of each of the plurality of nanophotonic microlenses, and the plurality of sub-dense areas may be symmetrically provided with respect to a region corresponding to the DTI structure of each of the plurality of nanophotonic microlenses. 
     Each of the plurality of nanophotonic microlenses may be formed such that center points of the plurality of sub-dense areas are provided in a region corresponding to a region between the DTI structure and center points of the plurality of photosensitive cells of each of the plurality of nanophotonic microlenses. 
     The plurality of first nanophotonic microlenses provided in a central region of the nanophotonic microlens array may be formed such that a first sparse area of each of the plurality of first nanophotonic microlenses corresponds to a center and an edge region of each of the plurality of first nanophotonic microlenses, and a plurality of first sub-dense areas of each of the plurality of first nanophotonic microlenses may be symmetrically provided with respect to a region corresponding to the DTI structure of each the plurality of first nanophotonic microlenses, each of a plurality of 2-1st nanophotonic microlenses provided in a left peripheral region of the nanophotonic microlens array may be formed such that center points of each of a plurality of 2-1st sub-dense areas of each of the plurality of 2-1st nanophotonic microlenses are respectively spaced apart from the each of center points of the plurality of photosensitive cells in the first direction, and may be provided to be closer to a center line of the DTI structure in the first direction than to each of the center points of the plurality of photosensitive cells, and each of a plurality of 2-2nd nanophotonic microlenses provided in a right peripheral region of the nanophotonic microlens array may be formed such that center points of each of a plurality of 2-2nd sub-dense areas of each of the plurality of 2-2nd nanophotonic microlenses are respectively spaced apart from the each of center points of the plurality of photosensitive cells in a direction opposite to the first direction, and may be provided to be closer to the center line of the DTI structure in the first direction than to each of the center points of the plurality of photosensitive cells. 
     The plurality of 2-1st sub-dense areas of each of the plurality of 2-1st nanophotonic microlenses and a plurality of 2-2nd sub-dense areas of each of the plurality of 2-2nd nanophotonic microlenses may be symmetrically provided in the second direction with respect to the center line of the DTI structure in the first direction. 
     The nanophotonic microlens array may include a plurality of third nanophotonic microlenses provided farther from a central region of an array of the nanophotonic microlenses than the plurality of 2-1st nanophotonic microlenses and the plurality of 2-2nd nanophotonic microlenses, and a distance by which a plurality of center points of a plurality of third sub-dense areas of each of the plurality of third nanophotonic microlenses are spaced apart from the plurality of center points of the plurality of photosensitive cells may be greater than a distance by which a plurality of center points of a plurality of 2-1st sub-dense areas and a plurality of 2-2nd sub-dense areas of each of the plurality of 2-1st nanophotonic microlenses and the plurality of 2-2nd nanophotonic microlenses are spaced apart from the plurality of center points of the plurality of photosensitive cells. 
     The plurality of pixels may include a plurality of first pixels each including a plurality of first photosensitive cells configured to sense light of a first wavelength band and a plurality of second pixels each including a plurality of second photosensitive cells configured to sense light of a second wavelength band that is shorter than the first wavelength band, the filter layer may include a plurality of first filters corresponding to the plurality of first pixels and configured to transmit light of the first wavelength band, and a plurality of second filters corresponding to the plurality of second pixels and configured to transmit light of the second wavelength band, and the nanophotonic microlens array may include a plurality of first nanophotonic microlenses corresponding to the plurality of first filters, respectively, and may be configured to focus light on the plurality of first pixels, and a plurality of second nanophotonic microlenses corresponding to the plurality of second filters, respectively, and configured to focus light on the plurality of second pixels. 
     An average diameter of a plurality of first nanostructures included in the dense area of each of the plurality of first nanophotonic microlenses may be less than an average diameter of a plurality of second nanostructures included in the dense area of each of the plurality of second nanophotonic microlenses. 
     Each of the plurality of first nanophotonic microlenses and each of the plurality of second nanophotonic microlenses provided in a central region of the nanophotonic microlens array may be formed such that a plurality of first sub-dense areas of each of the plurality of first nanophotonic microlenses are symmetrically provided with respect to a first region corresponding to the DTI structure of each of the plurality of first nanophotonic microlenses, and a plurality of second sub-dense areas of each of the plurality of second nanophotonic microlenses are symmetrically provided with respect to a second region corresponding to the DTI structure of each of the plurality of second nanophotonic microlenses, each of the plurality of first nanophotonic microlenses and each of the plurality of second nanophotonic microlenses provided in a left peripheral region of the nanophotonic microlens array may be formed such that center points of each of the plurality of first sub-dense areas of each of the plurality of first nanophotonic microlenses and center points of each of the plurality of second sub-dense areas of each of the plurality of second nanophotonic microlenses are respectively spaced apart from each of the center points of the plurality of photosensitive cells in the first direction, and are provided to be closer to a center line of the DTI structure in the first direction than to each of the center points of the plurality of photosensitive cells, and each of the plurality of first nanophotonic microlenses and each of the plurality of second nanophotonic microlenses provided in a right peripheral region of the nanophotonic microlens array may be formed such that center points of each of the plurality of first sub-dense areas of each of the plurality of first nanophotonic microlenses and center points of each of the plurality of second sub-dense areas of each of the plurality of second nanophotonic microlenses are respectively spaced apart from each of the center points of the plurality of photosensitive cells in a direction opposite to the first direction, and may be provided to be closer to a center line of the DTI structure in the first direction than to each of the center points of the plurality of photosensitive cells. 
     According to another aspect of an example embodiment, there is provided an electronic device including an optical sensor configured to convert an optical image into an electrical signal, and a processor configured to control an operation of the optical sensor, and store and output a signal generated by the optical sensor, wherein the optical sensor may include a sensor substrate including a plurality of pixels configured to sense incident light, a filter layer provided on the sensor substrate and including a plurality of filters respectively corresponding to the plurality of pixels, the plurality of filters being configured to transmit light of a certain wavelength band, and a nanophotonic microlens array provided on the filter layer and including a plurality of nanophotonic microlenses, each of the plurality of nanophotonic microlenses being configured to focus incident light on a corresponding pixel among the plurality of pixels, wherein each of the plurality of pixels includes a deep trench isolation (DTI) and a plurality of photosensitive cells that are electrically separated from each other by the DTI structure, and are two-dimensionally provided in a first direction and a second direction perpendicular to the first direction, each of the plurality of photosensitive cells being configured to independently sense light, wherein each of the plurality of nanophotonic microlenses is formed such that light transmitted through each of the nanophotonic microlenses have a phase profile having a plurality of convex regions and to collect incident light on each of a plurality of regions, which are spaced apart from centers of the plurality of photosensitive cells included in the corresponding pixel, toward the DTI structure, and wherein a portion of incident light transmitted through each of the plurality of nanophotonic microlenses is incident on the DTI structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a block diagram of an optical sensor according to an example embodiment; 
         FIGS.  2 ,  3 , and  4    are diagrams illustrating examples of a pixel arrangement of a pixel array of an optical sensor; 
         FIG.  5    is a conceptual diagram schematically illustrating a camera module according to an example embodiment; 
         FIG.  6    is a plan view of a pixel array of an optical sensor according to an example embodiment; 
         FIG.  7    is a perspective view illustrating an example configuration of a pixel array included in an optical sensor according to an example embodiment; 
         FIG.  8    is a plan view illustrating an example configuration of the pixel array of  FIG.  7   ; 
         FIG.  9    is a plan view illustrating an example configuration of a sensor substrate included in the pixel array of  FIG.  7   ; 
         FIG.  10    is a cross-sectional view taken along line A-A′ of the pixel array of  FIG.  7   ; 
         FIG.  11    is a cross-sectional view taken along line B-B′ of the pixel array of  FIG.  7   ; 
         FIG.  12    is a diagram illustrating a phase profile of light transmitted through a portion along line A-A′ of the pixel array of  FIG.  7   ; 
         FIG.  13    is a diagram illustrating a phase profile of light transmitted through a portion along line B-B′ of the pixel array of  FIG.  7   ; 
         FIG.  14    is a diagram illustrating a phase profile of light transmitted through a portion along line C-C′ of the pixel array of  FIG.  7   ; 
         FIG.  15    is a diagram illustrating a phase profile of light transmitted through a portion along line D-D′ of the pixel array of  FIG.  7   ; 
         FIG.  16    is a plan view illustrating an example configuration of a peripheral portion of a pixel array included in an optical sensor according to another example embodiment; 
         FIG.  17    is a cross-sectional view taken along line E-E′ in the peripheral portion of the pixel array of  FIG.  16   ; 
         FIG.  18    is a cross-sectional view taken along line F-F′ in the peripheral portion of the pixel array of  FIG.  16   ; 
         FIG.  19    is a diagram illustrating a phase profile of light transmitted through a portion along line E-E′ in the peripheral portion of the pixel array of  FIG.  16   ; 
         FIG.  20    is a plan view illustrating an example configuration of a pixel array included in an optical sensor, according to another example embodiment; 
         FIG.  21    is a cross-sectional view taken along line G-G′ of the pixel array of  FIG.  20   ; 
         FIG.  22    is a cross-sectional view taken along line H-H′ of the pixel array of  FIG.  20   ; 
         FIG.  23    is a diagram illustrating a phase profile of light transmitted through a portion along line G-G′ of the pixel array of  FIG.  7   ; 
         FIG.  24    is a diagram illustrating a phase profile of light transmitted through a portion along line H-H′ of the pixel array of  FIG.  7   ; 
         FIG.  25    is a plan view illustrating an example configuration of a pixel array included in an optical sensor according to another example embodiment; 
         FIG.  26    is a cross-sectional view taken along line I-I′ of the pixel array of  FIG.  25   ; 
         FIG.  27    is a cross-sectional view taken along line J-J′ of the pixel array of  FIG.  25   ; 
         FIG.  28    is a cross-sectional view taken along line K-K′ of the pixel array of  FIG.  25   ; 
         FIG.  29    is a cross-sectional view taken along line L-L′ of the pixel array of  FIG.  25   ; 
         FIG.  30    is a diagram illustrating a phase profile of light transmitted through a portion along line I-I′ of the pixel array of  FIG.  25   ; 
         FIG.  31    is a diagram illustrating a phase profile of light transmitted through a portion along line J-J′ of the pixel array of  FIG.  25   ; 
         FIG.  32    is a diagram illustrating a phase profile of light transmitted through a portion along line K-K′ of the pixel array of  FIG.  25   ; 
         FIG.  33    is a diagram illustrating a phase profile of light transmitted through a portion along line L-L′ of the pixel array of  FIG.  25   ; 
         FIG.  34    is a perspective view illustrating an example configuration of a pixel array included in an optical sensor according to another example embodiment; 
         FIG.  35    is a plan view illustrating an example configuration of the pixel array of  FIG.  34   ; 
         FIG.  36    is a plan view illustrating an example configuration of a first nanophotonic microlens included in the pixel array of  FIG.  34   ; 
         FIG.  37    is a plan view illustrating an example configuration of a pixel array included in an optical sensor according to another example embodiment; 
         FIG.  38    is a plan view illustrating an example configuration of a first nanophotonic microlens included in the pixel array of  FIG.  34   ; 
         FIG.  39    is a plan view illustrating an example configuration of a pixel array included in an optical sensor according to another example embodiment; 
         FIG.  40    is a plan view illustrating an example configuration of a pixel array included in an optical sensor according to another example embodiment; 
         FIG.  41    is a block diagram illustrating an electronic device including an image sensor according to an example embodiment; 
         FIG.  42    is a block diagram illustrating the camera module illustrated in  FIG.  41   ; and 
         FIGS.  43 ,  44 ,  45 ,  46 ,  47 ,  48 ,  49 ,  50 ,  51 , and  52    are diagrams illustrating various examples of electronic devices including optical sensors according to various example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the example embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the example embodiments are merely described below, by referring to the figures, to explain aspects. 
     As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expression, “at least one of a, b, and c,” should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c. 
     In the drawings, the size or thickness of each element may be exaggerated for clarity and convenience of description. 
     Terms such as “first” or “second” may be used to describe various elements, but the elements should not be limited by the terms. These terms are only used to distinguish one element from another element. 
     Throughout the specification, when a part “includes” an element, it is to be understood that the part may additionally include other elements rather than excluding other elements as long as there is no particular opposing recitation. 
       FIG.  1    is a block diagram of an optical sensor  1000  according to an example embodiment.  FIGS.  2  to  4    are diagrams illustrating examples of a pixel arrangement of a pixel array  1100  of the optical sensor  1000 .  FIG.  5    is a conceptual diagram illustrating a camera module  1880  according to an example embodiment.  FIG.  6    is a plan view of the pixel array  1100  of the optical sensor  1000 , according to an example embodiment. 
     Referring to  FIG.  1   , the optical sensor  1000  may include the pixel array  1100 , a timing controller  1010 , a row decoder  1020 , and an output circuit  1030 . The optical sensor  1000  may be, for example, a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor. 
     The pixel array  1100  includes a plurality of pixels that are two-dimensionally arranged along a plurality of rows and columns. The row decoder  1020  selects one of the rows of the pixel array  1100  in response to a row address signal output from the timing controller  1010 . The output circuit  1030  outputs, from the plurality of pixels arranged along the selected row, a light sensing signal in column units. To this end, the output circuit  1030  may include a column decoder and an analog-to-digital converter (ADC). For example, the output circuit  1030  may include a plurality of ADCs arranged for each column between the column decoder and the pixel array  1100  or one ADC arranged at an output terminal of the column decoder. The timing controller  1010 , the row decoder  1020 , and the output circuit  1030  may be implemented as a single chip or separate chips. A processor for processing an image signal output from the output circuit  1030  may be implemented as a single chip together with the timing controller  1010 , the row decoder  1020 , and the output circuit  1030 . 
     The pixel array  1100  may include a plurality of pixels that sense light of different wavelength bands. The plurality of pixels may be arranged in various manners. Various examples of a pixel arrangement of the pixel array  1100  of the optical sensor  1000  are illustrated in  FIGS.  2  to  4   . 
     First,  FIG.  2    shows a Bayer pattern that is used in general image sensors. Referring to  FIG.  2   , one unit pattern includes four quadrant regions, i.e., first to fourth quadrants, which may be a blue pixel B, a green pixel G, a red pixel R, and a green pixel G, respectively. The unit patterns are repeatedly arranged two-dimensionally in a first direction (y-direction) and a second direction (x-direction). In other words, two green pixels G are arranged in one diagonal direction in a 2×2 array-type unit pattern, and one blue pixel B and one red pixel R are arranged in the other diagonal direction. In the whole pixel arrangement, a first row in which a plurality of green pixels G and a plurality of blue pixels B are alternately arranged in the first direction (y-direction), and a second row in which a plurality of red pixels R and a plurality of green pixels G are alternately arranged in the first direction (y-direction) are repeatedly arranged in the second direction (x-direction). 
     The pixel array  1100  may be arranged in various manners other than the Bayer pattern. For example, referring to  FIG.  3   , the pixel array  1100  may also be arranged in a CYGM pattern in which a magenta pixel M, a cyan pixel C, a yellow pixel Y, and a green pixel G constitute one unit pattern. In addition, referring to  FIG.  4   , the pixel array  1100  may also be arranged in an RGBW pattern in which a green pixel G, a red pixel R, a blue pixel B, and a white pixel W constitute one unit pattern. The unit pattern may have a 3×2 array configuration. In addition, the plurality of pixels of the pixel array  1100  may be arranged in various manners according to the use and characteristics of the optical sensor  1000 . Hereinafter, it is described that the pixel array  1100  of the optical sensor  1000  has a Bayer pattern, however, the principles of embodiments described below may also be applied to a pixel arrangement other than the Bayer pattern. 
     The optical sensor  1000  may be applied to various optical devices. For example, referring to  FIG.  5   , the camera module  1880  according to an example embodiment may include a lens assembly  1910  that focuses light reflected from an object to form an optical image, an optical sensor  1000  that converts the optical image formed by the lens assembly  1910  into an electrical image signal, and an image signal processor  1960  that processes an electrical signal output from the optical sensor  1000  into an image signal. The camera module  1880  may further include an infrared cut-off filter arranged between the optical sensor  1000  and the lens assembly  1910 , a display panel for displaying an image formed by the image signal processor  1960 , and a memory for storing image data formed by the image signal processor  1960 . The camera module  1880  may be mounted in mobile electronic devices such as cellular phones, notebook computers, or tablet personal computers (PCs). 
     The lens assembly  1910  focuses an image of an object located outside the camera module  1880 , on the optical sensor  1000 , more specifically, on the pixel array  1100  of the optical sensor  1000 . Although  FIG.  5    illustrates that the lens assembly  1910  includes one lens for convenience of description, the lens assembly  1910  may include a plurality of lenses. When the pixel array  1100  is accurately located on a focal plane of the lens assembly  1910 , light starting from any one point of the object passes through the lens assembly  1910  and is then collected at one point on the pixel array  1100 . For example, light starting from a point A on an optical axis OX passes through the lens assembly  1910  and is then collected at the center of the pixel array  1100  on the optical axis OX. Light starting from a point B, C, or D, which deviates from the optical axis OX, travels across the optical axis OX by the lens assembly  1910  and is then collected at one point of a peripheral portion of the pixel array  1100 . For example, in  FIG.  5   , light starting from the point B above the optical axis OX is collected at the lower edge of the pixel array  1100  across the optical axis OX, and light starting from the point C below the optical axis OX is collected at the upper edge of the pixel array  1100  across the optical axis OX. In addition, light starting from the point D between the optical axis OX and the point B is collected at a point between the center and the lower edge of the pixel array  1100 . 
     Therefore, the light starting from the different points A, B, C, and D is incident on the pixel array  1100  at different angles according to the distances between the respective points A, B, C, and D and the optical axis OX. An angle of incidence of light on the pixel array  1100  is generally referred to as a chief ray angle (CRA). A chief ray CR refers to a ray incident on the pixel array  1100  from one point of the object through the center of the lens assembly  1910 , and a CRA refers to the angle between the chief ray and the optical axis OX. The light starting from the point A on the optical axis OX has a CRA of 0° and is perpendicularly incident on the pixel array  1100 . As the light emission point moves farther away from the optical axis OX, the CRA may increase. 
     From the viewpoint of the optical sensor  1000 , the CRA of the light incident on the center of the pixel array  1100  is 0°, and the CRA of incident light increases toward an edge of the pixel array  1100 . For example, the CRA of the light starting from the points B and C and incident on the outermost edges of the pixel array  1100  is greatest, and the CRA of the light starting from the point A and incident on the center of the pixel array  1100  is 0°. In addition, the CRA of the light starting from the point D and incident on the point between the center and the edge of the pixel array  1100  is less than the CRA of the light starting from the points B and C and greater than 0°. 
     Accordingly, the CRAs of light incident on the plurality of pixels in the pixel array  1100  depend on the positions of the respective pixels. For example, referring to  FIG.  6   , in a center  1100   a  included in a central region aa 1  of the pixel array  1100 , the CRA is 0° in both the first direction (y-direction) and the second direction (x-direction). In addition, as the distance from the center  1100   a  increases in the first direction (y-direction), the CRA in the first direction (y-direction) gradually increases, and the CRA in the first direction (y-direction) is greatest at left and right central edge portions  1100   b  and  1100   c  (i.e., the central edge portions in the first direction (y-direction)) included respectively in peripheral regions aa 2  and aa 3  of the pixel array  1100 . Also, as the distance from the center  1100   a  increases in the second direction (x-direction), the CRA in the second direction (x-direction) gradually increases, and the CRA in the second direction (x-direction) is greatest at upper and lower edge portions  1100   e  and  1100   h  (i.e., the edge portions in the second direction (x-direction)) included in the central region aa 1 . In addition, as the distance from the center  1100   a  increases in a diagonal direction, both the CRA in the first direction (y-direction) and the CRA in the second direction (x-direction) gradually increase, and the CRAs in the diagonal directions of the first direction (y-direction) and the second direction (x-direction) are greatest at vertex portions  1100   d ,  1100   f ,  1100   g , and  1100   i  are the largest. As the CRA of light incident on the plurality of pixels increases, the sensitivity of the pixels may decrease. 
     According to various example embodiments, in order to minimize the decrease in sensitivity of the pixels in the peripheral regions aa 2  and aa 3  of the pixel array  1100 , a specially designed nanophotonic microlens array may be arranged in the peripheral regions aa 2  and aa 3  of the pixel array  1100  of the optical sensor  1000 , as described below with reference to  FIGS.  16  to  19   . 
       FIG.  7    is a perspective view illustrating an example configuration of the pixel array  1100  included in the optical sensor  1000 , according to an example embodiment.  FIG.  8    is a plan view illustrating an example configuration of the pixel array  1100  of  FIG.  7   .  FIG.  9    is a plan view illustrating an example configuration of a sensor substrate  110  included in the pixel array  1100  of  FIG.  7   .  FIG.  10    is a cross-sectional view taken along line A-A′ of the pixel array  1100  of  FIG.  7   .  FIG.  11    is a cross-sectional view taken along line B-B′ of the pixel array  1100  of  FIG.  7   .  FIG.  12    is a diagram illustrating a phase profile of light transmitted through a portion along line A-A′ of the pixel array  1100  of  FIG.  7   .  FIG.  13    is a diagram illustrating a phase profile of light transmitted through a portion along line B-B′ of the pixel array  1100  of  FIG.  7   .  FIG.  14    is a diagram illustrating a phase profile of light transmitted through a portion along line C-C′ of the pixel array  1100  of  FIG.  8   .  FIG.  15    is a diagram illustrating a phase profile of light transmitted through a portion along line D-D′ of the pixel array  1100  of  FIG.  8   . 
     Referring to  FIGS.  7  through  9   , the pixel array  1100  may include the sensor substrate  110 , a filter layer  120 , and a nanophotonic microlens array  130 . The filter layer  120  may be provided on the sensor substrate  110 , and the nanophotonic microlens array  130  may be provided on the filter layer  120 . 
     The sensor substrate  110  may include a plurality of pixels  111 ,  112 ,  113 , and  114  (hereinafter, also referred to as a first pixel  111 , a second pixel  112 , a third pixel  113 , and a fourth pixel  114 ) that sense incident light Lf 1 . For example, the sensor substrate  110  may include the first pixel  111  and the fourth pixel  114  that sense light of a first wavelength band that is a green light region, the second pixel  112  that senses light of a second wavelength band that is a blue light region, and the third pixel  113  that senses light of a third wavelength band that is a red light region. The sensor substrate  110  may include a unit pattern in which the first pixel  111 , the second pixel  112 , the third pixel  113 , and the fourth pixel  114  are two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction), which is perpendicular to the first direction (y-direction). A plurality of unit patterns each including the first to fourth pixels  111 ,  112 ,  113 , and  114  may be two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). This arrangement is for sensing the incident light Lf 1  in a unit pattern such as a Bayer pattern. 
     The plurality of pixels  111 ,  112 ,  113 , and  114  may include deep trench isolation (DTI) structures d 1 , d 2 , d 3 , and d 4  (hereinafter, also referred to as a first DTI d 1 , a second DTI d 2 , a third DTI d 3 , and a fourth DTI d 4 ), and a plurality of photosensitive cells  111   a ,  111   b ,  111   c ,  111   d ,  112   a ,  112   b ,  112   c ,  112   d ,  113   a ,  113   b ,  113   c ,  113   d ,  114   a ,  114   b ,  114   c , and  114   d  (hereinafter, also referred to as a plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , a plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , a plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , and a plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d ) that are electrically separated from each other by the DTI structures d 1 , d 2 , d 3 , and d 4  to independently sense light, respectively. Each of the plurality of photosensitive cells  111   a ,  111   b ,  111   c ,  111   d ,  112   a ,  112   b ,  112   c ,  112   d ,  113   a ,  113   b ,  113   c ,  113   d ,  114   a ,  114   b ,  114   c , and  114   d  may include one photodiode. 
     For example, the first pixel  111  may include the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  that are two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). Referring to  FIG.  9   , the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  may be electrically separated from each other by the first DTI structure d 1 . The first DTI structure d 1  may have a cross shape, and the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  may be provided respectively in a second quadrant, a first quadrant, a third quadrant, and a fourth quadrant, which are formed by the first DTI structure d 1 . 
     The second pixel  112  may include the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d  that are two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). Referring to  FIG.  9   , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d  may be electrically separated from each other by the second DTI structure d 2 . The second DTI structure d 2  may have a cross shape, and the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d  may be provided respectively in a second quadrant, a first quadrant, a third quadrant, and a fourth quadrant, which are formed by the second DTI structure d 2 . 
     The third pixel  113  may include the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d  that are two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). Referring to  FIG.  9   , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d  may be electrically separated from each other by the third DTI structure d 3 . The third DTI structure d 3  may have a cross shape, and the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d  may be provided respectively in a second quadrant, a first quadrant, a third quadrant, and a fourth quadrant, which are formed by the third DTI structure d 3 . 
     The fourth pixel  113  may include the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d  that are two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). Referring to  FIG.  9   , the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d  may be electrically separated from each other by the fourth DTI structure d 4 . The fourth DTI structure d 4  may have a cross shape, and the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d  may be provided respectively in a second quadrant, a first quadrant, a third quadrant, and a fourth quadrant, which are formed by the fourth DTI structure d 4 . 
     In addition, referring to  FIG.  9   , the first pixel  111 , the second pixel  112 , the third pixel  113 , and the fourth pixel  114  may be electrically separated from each other by an additional DTI structure d 5 . The additional DTI structure d 5  may have a cross shape, and the first to fourth pixels  111  to  114  may be provided respectively in a second quadrant, a first quadrant, a third quadrant, and a fourth quadrant, which are formed by the additional DTI structure d 5 . 
     The filter layer  120  may include a plurality of filters  121 ,  122 ,  123 , and  124  (hereinafter, also referred to as a first filter  121 , a second filter  122 , a third filter  123 , and a fourth filter  124 ), each of which transmits only light of a certain wavelength band and absorbs or reflects light of other wavelength bands. The plurality of filters  121 ,  122 ,  123 , and  124  may be provided to correspond to the plurality of pixels  111 ,  112 ,  113 , and  114 , respectively. For example, the filter layer  120  may include the first filter  121  arranged on the first pixel  111  to transmit only light of the first wavelength band, the second filter  122  arranged on the second pixel  112  to transmit only light of the second wavelength band that is different from the first wavelength band, the third filter  123  arranged on the third pixel  113  to transmit only light of the third wavelength band that is different from the first and second wavelength bands, and the fourth filter  124  arranged on the fourth pixel  114  to transmit only light of the first wavelength band. 
     Accordingly, the first filter  121  and the second filter  122  may be alternately arranged in the first direction (y-direction), and the third filter  123  and the fourth filter  124  may be alternately arranged in a cross-section at a different position in the second direction (x-direction) from the cross-section in which the first filter  121  and the second filter  122  are arranged. For example, the first and fourth filters  121  and  124  may transmit only green light, the second filter  122  may transmit only blue light, and the third filter  123  may transmit only red light. The first to fourth filters  121  to  124  may be two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). 
     The nanophotonic microlens array  130  may be arranged on the filter layer  120 . The nanophotonic microlens array  130  may include a plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  (hereinafter, also referred to as a first nanophotonic microlens  131 , a second nanophotonic microlens  132 , a third nanophotonic microlens  133 , and a fourth nanophotonic microlens  134 ) that are two-dimensionally arranged. The plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may correspond to the plurality of filters  121 ,  122 ,  123 , and  124 , respectively, and may correspond to the plurality of pixels  111 ,  112 ,  113 , and  114 , respectively. For example, the nanophotonic microlens array  130  may include the first nanophotonic microlens  131  arranged on the first filter  121 , the second nanophotonic microlens  132  arranged on the second filter  122 , the third nanophotonic microlens  133  arranged on the third filter  123 , and the fourth nanophotonic microlens  134  arranged on the fourth filter  124 . Accordingly, the first nanophotonic microlens  131  and the second nanophotonic microlens  132  may be alternately arranged in the first direction (y-direction), and the third nanophotonic microlens  133  and the fourth nanophotonic microlens  134  may be alternately arranged in a cross-section at a different position in the second direction (x-direction) from the cross-section in which the nanophotonic microlens  131  and the second nanophotonic microlens  132  are arranged. 
     The first to fourth nanophotonic microlenses  131  to  134  may be two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction) to face the corresponding filters and the corresponding pixels, respectively. For example, the first pixel  111 , the first filter  121 , and the first nanophotonic microlens  131  may be arranged to face each other in a third direction (z-direction), which is perpendicular to the first direction (y-direction) and the second direction (x-direction). In addition, the second pixel  112 , the second filter  122 , and the second nanophotonic microlens  132  may be arranged to face each other in the third direction (z-direction), the third pixel  113 , the third filter  123 , and the third nanophotonic microlens  133  may be arranged to face each other in the third direction (z-direction), and the fourth pixel  114 , the fourth filter  124 , and the fourth nanophotonic microlens  134  may be arranged to face each other in the third direction (z-direction). In this case, the first to fourth nanophotonic microlenses  131  to  134  and the first to fourth DTI structures d 1  to d 4  may be arranged such that the center points of the first to fourth nanophotonic microlenses  131  to  134  are located on the same axis as the center points of the first to fourth DTI structures d 1  to d 4  in the third direction (z-direction), respectively. 
     The first to fourth nanophotonic microlenses  131  to  134  may focus the incident light Lf 1  on the corresponding pixels among the plurality of pixels  111 ,  112 ,  113 , and  114 , respectively. For example, the first nanophotonic microlens  131  may focus the incident light Lf 1  on the first pixel  111 . Similarly, the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may focus the incident light Lf 1  on the second to fourth pixels  112 ,  113 , and  114 , respectively. 
     In the incident light Lf 1  that is focused on the sensor substrate  110  by the nanophotonic microlens array  130 , only light of the first wavelength band may be transmitted through the first and fourth filters  121  and  124  to be collected in the first and fourth pixels  111  and  114 , only light of the second wavelength band may be transmitted through the second filter  122  to be collected in the second pixel  112 , and only light of the third wavelength band may be transmitted through the third filter  123  to be collected in the third pixel  113 . 
     The plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may be formed to focus the incident light Lf 1  respectively on a plurality of regions, which are spaced apart, toward the DTI structures d 1 , d 2 , d 3 , and d 4 , respectively, from the centers of the plurality of photosensitive cells  111   a ,  111   b ,  111   c ,  111   d ,  112   a ,  112   b ,  112   c ,  112   d ,  113   a ,  113   b ,  113   c ,  113   d ,  114   a ,  114   b ,  114   c , and  114   d  included in the corresponding pixels  111 ,  112 ,  113 , and  114 , respectively. In this case, portions of the incident light Lf 1  transmitted through the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134 , respectively, may be incident on the DTI structures d 1 , d 2 , d 3 , and d 4 , respectively. 
     For example, as illustrated in  FIG.  8   , the first nanophotonic microlens  131  may focus the incident light Lf 1  on a plurality of regions, which are spaced apart from the centers of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , respectively, toward the first DTI structure d 1 . In this case, a portion of the incident light Lf 1  transmitted through the first nanophotonic microlens  131  may be incident on the first DTI structure d 1 . 
     The first nanophotonic microlens  131  may be formed such that light transmitted through the first nanophotonic microlens  131  has a phase profile having a plurality of convex regions. In this case, the light transmitted through the first nanophotonic microlens  131  may be collected more on the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  than on the first DTI structure d 1 . As described above, the amount of the incident light Lf 1  collected on the center of the first DTI structure d 1  may be reduced by the first nanophotonic microlens  131 . Similarly, the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may also be formed such that light transmitted respectively through the second to fourth nanophotonic microlenses  132 ,  133 , and  134  has a phase profile having a plurality of convex regions, and accordingly, the amount of the incident light Lf 1  collected on the centers of the second to fourth DTI structures d 2 , d 3 , and d 4  may be reduced. 
     Each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may include a convex lens structure having a plurality of convex portions. For example, each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may include a single convex lens structure in which a plurality of convex lens-shaped portions, the number of which corresponds to the number of photosensitive cells included in each of the pixels corresponding to the nanophotonic microlens, partially overlap each other about the center point of the nanophotonic microlens. Accordingly, the number of convex portions included in each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may be equal to the number of photosensitive cells included in the corresponding one of the plurality of pixels  111 ,  112 ,  113 , and  114 , which corresponds to each of the plurality of nanophotonic microlens  131 ,  132 ,  133 , and  134 . 
     For example, as illustrated in  FIGS.  7  and  8   , the first nanophotonic microlens  131  may include a single convex lens structure in which a plurality of convex lens-shaped portions, the number of which corresponds to the number of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  included in the corresponding first pixel  111 , partially overlap each other about the center point of the first nanophotonic microlens  131 . For example, the first pixel  111  may include four first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , and the first nanophotonic microlens  131  may include a single convex lens structure in which four convex lens-shaped portions partially overlap each other about the center point of first nanophotonic microlens  131 . In this case, the first nanophotonic microlens  131  has the plurality of convex lens-shaped portions that overlap each other without gaps about the center point thereof, and accordingly, no opening may be formed in the center of the first nanophotonic microlens  131 . Accordingly, a change in phase of light passing through the center of the first nanophotonic microlens  131  may occur. 
     In addition, the degree of overlapping of the four convex lens-shaped portions of the first nanophotonic microlens  131  may be variously designed as necessary. As the degree of overlapping of the four convex lens-shaped portions of the first nanophotonic microlens  131  increases, the amount of the incident light Lf 1  on the first DTI structure d 1  increases and the amount of light collected on the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  decreases. On the other hand, as the degree of overlapping of the four convex lens-shaped portions of the first nanophotonic microlens  131  decreases, the amount of the incident light Lf 1  on the first DTI structure d 1  decreases and the amount of light collected on the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  increases. 
     Similar to the first nanophotonic microlens  131 , each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may have a single convex lens structure in which a plurality of convex lens-shaped portions, the number of which corresponds to the number of photosensitive cells included in the corresponding pixel, i.e., the number of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the number of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the number of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d  included in the corresponding one of the plurality of pixels  112 ,  113 , and  114 , partially overlap each other about the center point of the nanophotonic microlens. 
     The first nanophotonic microlens  131  may have a concave portion in a boundary region where the plurality of convex portions overlap each other. For example, the plurality of convex portions of the first nanophotonic microlens  131  may overlap each other in a first region corresponding to the first DTI structure d 1 , and the first region of the first nanophotonic microlens  131  may be concave. The plurality of convex portions may be formed in a second region that is the remaining region other than the first region in the first nanophotonic microlens  131 . In this case, the plurality of convex portions included in the first nanophotonic microlens  131  may be symmetrically distributed with respect to the first region corresponding to the first DTI structure d 1  of the first nanophotonic microlens  131 . 
     Similarly, each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may also have a concave portion in a boundary region where the plurality of convex portions overlap each other. For example, the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may have the concave portions in first regions corresponding to the second to fourth DTI structures d 2 , d 3 , and d 4 , respectively. In addition, the plurality of convex portions of each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may be formed in a second region that is the remaining region other than the first region in each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134 . In this case, the plurality of convex portions included in each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may be symmetrically distributed with respect to the first region corresponding to the second, third, or fourth DTI structure d 2 , d 3 , or d 4  of the nanophotonic microlens. 
     Furthermore, each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may be formed such that maximum points of the plurality of convex portions are provided in a third region, which corresponds to regions between the DTI structure d 1 , d 2 , d 3 , or d 4  of each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  and the center points of the plurality of photosensitive cells, i.e., the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d.    
     For example, referring to  FIG.  8   , maximum points s 1 , s 2 , s 3 , and s 4  of the plurality of convex portions of the first nanophotonic microlens  131  may be provided in a third region an, which corresponds to regions between the first DTI structure d 1  and center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d . In this case, for example, the maximum points s 1 , s 2 , s 3 , and s 4  of the plurality of convex portions of the first microlens  131  may be formed to be closer to the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , than to the center point of the first DTI structure d 1 . However, embodiments are not limited thereto, and the maximum points s 1 , s 2 , s 3 , and s 4  of the plurality of convex portions of the first nanophotonic microlens  131  may be formed to be closer to the center point of the first DTI structure d 1  than to the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d . In addition, the maximum points s 1 , s 2 , s 3 , and s 4  of the plurality of convex portions of the first nanophotonic microlens  131  may be symmetrically distributed with respect to the center point of the first DTI structure d 1 . 
     As described above, the maximum points s 1 , s 2 , s 3 , and s 4  of the plurality of convex portions of the first nanophotonic microlens  131  are formed to be spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , respectively, toward the center point of the first DTI structure d 1 , and thus, a portion of the incident light Lf 1  may be collected on the central region of the first DTI structure d 1  in contact with the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , and the other portions of the incident light Lf 1  may be collected on the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , respectively. 
     In this case, because one pixel, e.g., the first pixel  111 , includes the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , each of which independently senses light, an autofocus signal may be provided in a phase-detection autofocus manner by using a difference between signals output from the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  by the light incident on the central region of the first DTI structure d 1  that is in contact with the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d.    
     In addition, because the other portions of the incident light Lf 1  deviate from the central region of the first DTI structure d 1  that is in contact with the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , and is collected on the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , light loss that may occur when the incident light Lf 1  is incident intensively on the central region of the first DTI structure d 1  in contact with the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , and thus most of the incident light Lf 1  is absorbed by the first DTI structure d 1 , may be suppressed. 
     Similarly, the maximum points of the plurality of convex portions of each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may be provided in a third region, which corresponds to regions between the second, third, or fourth DTI structure d 2 , d 3 , or d 4  and the central points of the corresponding photosensitive cells, i.e., the central points of the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d.    
     Referring to  FIGS.  10  and  11   , the light transmitted through the first nanophotonic microlens  131  may be collected on the first pixel  111  through the first filter  121 . In this case, light transmitted through the concave central region of the first nanophotonic microlens  131  may be collected on the central region of the first DTI structure d 1  included in the first pixel  111 , and light transmitted through the plurality of convex portions of the first nanophotonic microlens  131  may be collected on the first photosensitive cells  111   a ,  111   b , and  111   c  included in the first pixel  111 . Although  FIGS.  10  and  11    illustrate only the first photosensitive cells  111   a ,  111   b , and  111   c  provided in the first to third quadrants formed by the first DTI structure d 1 , light may also be collected on the first photosensitive cell  111   d  provided in the fourth quadrant, similarly to the light collected on the first photosensitive cells  111   a ,  111   b , and  111   c  provided in the first to third quadrants. In addition, similar to the first nanophotonic microlens  131 , light transmitted through the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may be collected on the second to fourth pixels  112 ,  113 , and  114 , respectively. 
     Each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may be formed such that light transmitted through each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  has a phase profile having a plurality of convex regions. For example, referring to  FIGS.  12  and  13   , light transmitted through the first nanophotonic microlens  131  may have a phase profile in which a plurality of convex regions overlap each other. In this case, the number of convex regions included in the phase profile of the light transmitted through the first nanophotonic microlens  131  may be equal to the number of photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  included in the first pixel  111  corresponding to the first nanophotonic microlens  131 . The plurality of convex regions in the phase profile of the light transmitted through the first nanophotonic microlens  131  may be regions distinguished from each other with the concave region therebetween, and may be two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). The plurality of convex regions may be two-dimensionally arranged and overlap each other by a certain amount, and the region in which the plurality of convex regions overlap each other may be more concave than the plurality of convex regions. 
     Similarly, light transmitted through each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may have a phase profile in which a plurality of convex regions overlap each other. In this case, the number of convex regions in the phase profile of the light transmitted through each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may be equal to the number of photosensitive cells, i.e., the number of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the number of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the number of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d , included in the pixel  112 ,  113 , or  114  corresponding to the second to fourth nanophotonic microlenses  132 ,  133 , and  134 . 
     Each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may be formed such that light transmitted through the first region corresponding to the first, second, third, or fourth DTI structure d 1 , d 2 , d 3 , or d 4  of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  has a phase profile having a region where the plurality of convex regions overlap each other, and light transmitted through the second region that is the remaining region other than the first region of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  has a phase profile having a plurality of convex regions. In addition, each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may be formed such that the light transmitted through each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  has a phase profile including a plurality of convex regions that are symmetrically distributed with respect the first region corresponding to the first, second, third, or fourth DTI structure d 1 , d 2 , d 3 , or d 4 . 
     For example, referring to  FIGS.  8  and  12   , light transmitted through a first region a 1  corresponding to the second DTI structure d 2  of the second nanophotonic microlens  132  may have a phase profile having a region where a plurality of convex regions overlap each other, and light transmitted through a second region a 2  that is the remaining region other than the first region a 1  in the second nanophotonic microlens  132  may have a phase profile having a region having the plurality of convex regions. Although  FIGS.  8  and  12    illustrate that the first region a 1  and the second region a 2  are as partial regions of the second nanophotonic microlens  132 , which correspond to the first quadrant and the second quadrant formed by the second DTI structure d 2 , this is merely an example for convenience of description, and the first region a 1  may refer to all regions corresponding to the second DTI structure d 2  of the second nanophotonic microlens  132 , and the second region a 2  may refer to the remaining regions other than the regions corresponding to the second DTI structure d 2  of the second nanophotonic microlens  132 . In this case, the light transmitted through the second nanophotonic microlens  132  may have a phase profile including a plurality of convex regions that are symmetrically distributed with respect the first region a 1 . 
     Each of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  may be formed such that the phase profile of light transmitted through the third region, which corresponds to regions between each of the DTI structure d 1 , d 2 , d 3 , or d 4  of the plurality of nanophotonic microlenses  131 ,  132 ,  133 , and  134  and the center points of the plurality of photosensitive cells, i.e., the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d , has a plurality of maximum points. 
     For example, referring to  FIGS.  8  and  12  to  15   , light transmitted through the third region an of the first nanophotonic microlens  131  may have a phase profile including a plurality of maximum points. In this case, the phases of light transmitted through the maximum points s 1 , s 2 , s 3 , and s 4  included in the third region an of the first nanophotonic microlens  131  may have maximum values. In addition, the number of maximum points included in the phase profile of the light transmitted through the third region an of the first nanophotonic microlens  131  may be equal to the number of maximum points s 1 , s 2 , s 3 , and s 4  included in the third region an of the first nanophotonic microlens  131 . 
     Referring to  FIGS.  8  and  12   , the phase of light transmitted through a minimum point p 1  corresponding to the center between the center points c 2  and c 1  of two photosensitive cells, that is, the photosensitive cells  111   b  and  111   a , provided in the first and second quadrants formed by the first DTI structure d 1  in the first nanophotonic microlens  131  may have a minimum value. Similarly, referring to  FIGS.  8  and  13   , the phase of light transmitted through a minimum point p 2  corresponding to the center between the center points c 1  and c 3  of two photosensitive cells, that is, the photosensitive cells  111   a  and  111   c , provided in the second and third quadrants formed by the first DTI structure d 1  in the first nanophotonic microlens  131  may have a minimum value. Regions corresponding to the minimum points p 1  and p 2  of the first nanophotonic microlens  131  may correspond to a portion of the first DTI structure d 1 . 
     In addition, referring to  FIGS.  8  and  14   , the phases of light transmitted through two maximum points s 1  and s 4  provided between the center points c 1  and c 4  of two photosensitive cells, that is, the photosensitive cells  111   a  and  111   d , provided in the second and fourth quadrants formed by the first DTI structure d 1  in the first nanophotonic microlens  131  may have maximum values. Furthermore, referring to  FIGS.  8  and  15   , the phases of light transmitted through two maximum points s 2  and s 3  provided between the center points c 2  and c 3  of two photosensitive cells, that is, the photosensitive cells  111   b  and  111   c , provided in the first and third quadrants formed by the first DTI structure d 1  in the first nanophotonic microlens  131  may have maximum values. 
     Similar to the first nanophotonic microlens  131 , the light transmitted through the third region of each of the second to fourth nanophotonic microlenses  132 ,  133 , and  134  may have a phase profile including a plurality of maximum points. 
       FIG.  16    is a plan view illustrating an example configuration of a peripheral portion of a pixel array  1110  included in the optical sensor  1000 , according to another example embodiment.  FIG.  17    is a cross-sectional view taken along line E-E′ in the peripheral portion of the pixel array  1110  of  FIG.  16   .  FIG.  18    is a cross-sectional view taken along line F-F′ in the peripheral portion of the pixel array  1110  of  FIG.  16   .  FIG.  19    is a diagram illustrating a phase profile of light transmitted through a portion along line E-E′ in the peripheral portion of the pixel array  1110  of  FIG.  16   . 
     The pixel array  1110  of  FIGS.  16  to  18    may be substantially the same as the pixel array  1100  of  FIG.  7   , except that the configuration of a nanophotonic microlens array  140  is different from that of the nanophotonic microlens array  130  of  FIG.  7   . In  FIG.  16   , for convenience of description, the sensor substrate  110  and the filter layer  120  included in the pixel array  1110  are omitted. In describing  FIGS.  16  to  18   , descriptions that are provided in connection with  FIGS.  1  to  15    are omitted. Also, in describing  FIGS.  16  to  18   , the reference numerals of the components illustrated in  FIGS.  1  to  15    are used. 
     The configuration of the central region aa 1  (see  FIG.  6   ) of the nanophotonic microlens array  140  included in the pixel array  1110  of  FIGS.  16  to  18    may be the same as that of the nanophotonic microlens array  130  included in the pixel array  1100  of  FIG.  7   . 
     According to another example embodiment, the configuration of the peripheral regions aa 2  and aa 3  (see  FIG.  6   ) of the nanophotonic microlens array  140  may be different from that of the nanophotonic microlens array  130 . However, the configuration of the nanophotonic microlens array  140  may be substantially the same as that of the nanophotonic microlens array  130  of  FIG.  7    in that each of a plurality of nanophotonic microlenses  141 ,  142 ,  143 , and  144  (hereinafter, also referred to as first to fourth nanophotonic microlenses  141  to  144 ) arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  includes a plurality of convex portions, first regions corresponding to DTI structures of the plurality of nanophotonic microlenses  141 ,  142 ,  143 , and  144  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  are concave, and the plurality of convex portions are formed in a second region that is the remaining region other than the first region. 
     Hereinafter, characteristics of the plurality of nanophotonic microlenses  141 ,  142 ,  143 , and  144  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140 , which are distinguished from the configuration of the nanophotonic microlens array  130  of  FIG.  7   , will be described. 
     Referring to  FIGS.  16  to  18   , each of the plurality of nanophotonic microlenses  141 ,  142 ,  143 , and  144  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may be formed such that maximum points of a plurality of convex portions of each of the plurality of nanophotonic microlenses  141 ,  142 ,  143 , and  144  are spaced apart from the respective center points of the plurality of photosensitive cells, i.e., the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d , in the first direction (y-direction), and are distributed to be closer to the center line of the DTI structure in the first direction (y-direction) than to each of the center points of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d.    
     For example, the first nanophotonic microlens  141  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may be formed such that maximum points s 5 , s 6 , s 7 , and s 8  of the plurality of convex portions of the first nanophotonic microlens  141  are spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction), and are distributed closer to a center line dcl of the first DTI structure d 1  in the first direction (y-direction) than to the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d.    
     In this case, unlike the maximum points s 1 , s 2 , s 3 , and s 4  of the first nanophotonic microlens  131  of  FIGS.  7  and  8   , the maximum points s 5 , s 6 , s 7 , and s 8  of the first nanophotonic microlens  141  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may be distributed to be spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  all in the first direction (y-direction). 
     As illustrated in  FIG.  17   , the first nanophotonic microlens  141  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may include a plurality of convex portions periodically arranged in the first direction (y-direction). In this case, the maximum points of the plurality of convex portions included in the first nanophotonic microlens  141  may be formed to be spaced apart from the center points of the plurality of photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  included in the corresponding first pixel  111  in the first direction (y-direction). 
     In this case, the phase profile of light transmitted through the first and second nanophotonic microlenses  141  and  142  in the first direction (y-direction), which are arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  and includes the plurality of convex portions are periodically arranged in the first direction (y-direction), may have a phase profile in which a linear phase profile inclined in the first direction (y-direction) and a convex phase profile are mixed together. For example, as illustrated in  FIG.  19   , the light transmitted through the first and second nanophotonic microlenses  141  and  142  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may have a phase profile in which a plurality of inclined linear phase profiles k 1 , k 2 , k 3 , and k 4  and a plurality of convex phase profiles are mixed with each other, respectively, in the first direction (y-direction). Accordingly, even when the CRA of the light incident on the first and second nanophotonic microlenses  141  and  142  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  is greater than 0°, the difference between the amount of light collected on the plurality of photosensitive cells arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  and the amount of light collected on the plurality of photosensitive cells arranged in the central region aa 1  may be minimized. 
     Moreover, as illustrated in  FIGS.  16  and  18   , the plurality of convex portions of the first nanophotonic microlens  141  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may be symmetrically distributed in the second direction (x-direction) with respect to the center line dcl of the first DTI structure d 1  in the first direction (y-direction). In this case, the phase profile, in the second direction (x-direction), of the light transmitted through the first nanophotonic microlens  141 , which includes the plurality of convex portions symmetrically arranged in the second direction (x-direction) and is arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140 , may be the same as illustrated in  FIG.  13   . 
     In addition, as the distance between the central region aa 1  of the nanophotonic microlens array  140  and the first nanophotonic microlens  141  increases, the distances between the maximum points s 5 , s 6 , s 7 , and s 8  of the first nanophotonic microlens  141  and the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction) may also increase. For example, the nanophotonic microlens array  140  may include a 1-1st nanophotonic microlens arranged at one point in the peripheral regions aa 2  and aa 3 , and a 1-2nd nanophotonic microlens arranged farther from the central region aa 1  than the 1-1st nanophotonic microlens. In this case, the distance between the maximum points of the plurality of convex portions of the 1-2nd nanophotonic microlens and the center points of the plurality of photosensitive cells corresponding to the 1-2nd nanophotonic microlens may be greater than the distance between the maximum points of the plurality of convex portions the 1-1st nanophotonic microlens and the center points of the plurality of photosensitive cells corresponding to the 1-1st nanophotonic microlens. Accordingly, despite the fact that the CRA of incident light increases toward the edge of the nanophotonic microlens array  140 , the phase change of the incident light may also increase to that extent, and consequently, the difference between the amount of light collected on the plurality of photosensitive cells arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  and the amount of light collected on the plurality of photosensitive cells arranged in the central region aa 1  may be minimized. 
     Furthermore, a first slope of a linear phase profile inclined in the first direction (y-direction) of light transmitted through the 1-1st nanophotonic microlens arranged at one point in the peripheral regions aa 2  and aa 3  included in the nanophotonic microlens array  140  may be less than a second slope of a linear phase profile inclined in the first direction (y-direction) of light transmitted through the 1-2nd nanophotonic microlens arranged farther from the central region aa 1  than the 1-1st nanophotonic microlens. 
     Similarly, the second to fourth nanophotonic microlenses  142 ,  143 , and  144  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may be formed such that maximum points of each of the second to fourth nanophotonic microlenses  142 ,  143 , and  144  are spaced apart from the respective center points of the plurality of photosensitive cells  112   a ,  112   b ,  112   c ,  112   d ,  113   a ,  113   b ,  113   c ,  113   d ,  114   a ,  114   b ,  114   c , and  114   d  in the first direction (y-direction), and are distributed to be closer to the respective center lines of the second to fourth DTI structures d 2 , d 3 , and d 4  in the first direction (y-direction) than to the center points of the plurality of photosensitive cells corresponding to the second to fourth nanophotonic microlenses  142 ,  143 , and  144 . 
     In addition, the plurality of convex portions of the second to fourth nanophotonic microlenses  142 ,  143 , and  144  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  may be symmetrically distributed in the second direction (x-direction) with respect to the center lines of the second to fourth DTI structures d 2 , d 3 , and d 4  in the first direction (y-direction), respectively. 
     Also, light incident on the left peripheral region aa 2  among the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  140  is incident on the pixel array  1110  at an angle in the opposite direction to the direction of light incident on the right peripheral region aa 3 , with respect to the normal line of the pixel array  1110 . Accordingly, the first to fourth nanophotonic microlenses  141  to  144  arranged in the left peripheral region aa 2  of the nanophotonic microlens array  140  may have a shape inverted, in the first direction (y-direction), from the shape of the first to fourth nanophotonic microlens  141  to  144  arranged in the right peripheral region aa 3 . 
       FIG.  20    is a plan view illustrating an example configuration of a pixel array  1120  included in the optical sensor  1000 , according to another example embodiment.  FIG.  21    is a cross-sectional view taken along line G-G′ of the pixel array  1120  of  FIG.  20   .  FIG.  22    is a cross-sectional view taken along line H-H′ of the pixel array  1120  of  FIG.  20   .  FIG.  23    is a diagram illustrating a phase profile of light transmitted through a portion along line G-G′ of the pixel array  1120  of  FIG.  7   .  FIG.  24    is a diagram illustrating a phase profile of light transmitted through a portion along line H-H′ of the pixel array  1120  of  FIG.  7   . 
     The pixel array  1120  of  FIGS.  20  to  22    may be substantially the same as the pixel array  1100  of  FIG.  7   , except that a plurality of nanophotonic microlenses  151 ,  152 ,  153 , and  154  (hereinafter, also referred to as first to fourth nanophotonic microlenses  151  to  154 ) included in a nanophotonic microlens array  150  have different shapes according to wavelengths of light sensed by corresponding pixels, unlike the nanophotonic microlens array  130  of  FIG.  7   . In  FIG.  20   , for convenience of description, the filter layer  120  included in the pixel array  1120  is omitted. In describing  FIGS.  20  to  22   , descriptions that are provided in connection with  FIGS.  1  to  15    are omitted. Also, in describing  FIGS.  20  to  22   , the reference numerals of the components illustrated in  FIGS.  1  to  15    are used. 
     Referring to  FIGS.  20  to  22   , the nanophotonic microlens array  150  may include the first nanophotonic microlens  151  and the fourth nanophotonic microlens  154  respectively corresponding to the first pixel  111  and the fourth pixel  114  that sense light of the first wavelength band, which is the green light region. The first and fourth nanophotonic microlenses  151  and  154  may correspond to the first filter  121  and the fourth filter  124 , respectively. The first and fourth nanophotonic microlenses  151  and  154  may focus light on the first pixel  111  and the fourth pixel  114 , respectively. 
     In addition, the nanophotonic microlens array  150  may include the second nanophotonic microlens  152  corresponding to the second pixel  112  that senses light of the second wavelength band, which is the blue light region. The second nanophotonic microlens  152  may correspond to the second filter  122 . The second nanophotonic microlens  152  may focus light on the second pixel  112 . 
     Furthermore, the nanophotonic microlens array  150  may include the third nanophotonic microlens  153  corresponding to the third pixel  113  that senses light of the third wavelength band, which is the red light region. The third nanophotonic microlens  153  may correspond to the third filter  123 . The third nanophotonic microlens  153  may focus light on the third pixel  113 . 
     Here, each of the plurality of nanophotonic microlenses  151 ,  152 ,  153 , and  154  may have a plurality of convex portions, which are more convex as the wavelength band of light sensed by the corresponding pixel is shorter. For example, as illustrated in  FIG.  21   , a plurality of second convex portions of the second nanophotonic microlens  152  corresponding to the second pixel  112  that senses light of the second wavelength band, which is the blue light region, may be formed to be more convex than a plurality of first convex portions of the first nanophotonic microlens  151  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region. In addition, as illustrated in  FIG.  22   , the plurality of first convex portions of the first nanophotonic microlens  151  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region, may be formed to be more convex than a plurality of third convex portions of the third nanophotonic microlens  153  corresponding to the third pixel  113  that senses light of the third wavelength band, which is the red light region. Furthermore, a plurality of fourth convex portions of the fourth nanophotonic microlens  154  corresponding to the fourth pixel  114  that senses light of the first wavelength band, which is the green light region, may have the same shape as that of the plurality of first convex portions of the first nanophotonic microlens  151 . 
     In this case, as illustrated in  FIG.  23   , a plurality of second convex regions included in the phase profile of light transmitted through the second nanophotonic microlens  152  may be more convex than a plurality of first convex regions included in the phase profile of light transmitted through the first nanophotonic microlens  151 . For example, the phase change of the light transmitted through the second nanophotonic microlens  152  may be substantially greater than the phase change of the light transmitted through the first nanophotonic microlens  151 . 
     In addition, as illustrated in  FIG.  24   , a plurality of first convex regions included in the phase profile of light transmitted through the first nanophotonic microlens  151  may be more convex than a plurality of third convex regions included in the phase profile of light transmitted through the third nanophotonic microlens  153 . For example, the phase change of the light transmitted through the first nanophotonic microlens  151  may be substantially greater than the phase change of the light transmitted through the third nanophotonic microlens  153 . 
     Furthermore, a plurality of fourth convex regions included in the phase profile of light transmitted through the fourth nanophotonic microlens  154  may have the same shape as the plurality of first convex regions included in the phase profile of the light transmitted through the first nanophotonic microlens  151 . 
       FIG.  25    is a plan view illustrating an example configuration of a pixel array  1130  included in the optical sensor  1000 , according to another example embodiment.  FIG.  26    is a cross-sectional view taken along line I-I′ of the pixel array  1130  of  FIG.  25   .  FIG.  27    is a cross-sectional view taken along line J-J′ of the pixel array  1130  of  FIG.  25   .  FIG.  28    is a cross-sectional view taken along line K-K′ of the pixel array  1130  of  FIG.  25   .  FIG.  29    is a cross-sectional view taken along line L-L′ of the pixel array  1130  of  FIG.  25   .  FIG.  30    is a diagram illustrating a phase profile of light transmitted through a portion along line I-I′ of the pixel array  1130  of  FIG.  25   .  FIG.  31    is a diagram illustrating a phase profile of light transmitted through a portion along line J-J′ of the pixel array  1130  of  FIG.  25   .  FIG.  32    is a diagram illustrating a phase profile of light transmitted through a portion along line K-K′ of the pixel array  1130  of  FIG.  25   .  FIG.  33    is a diagram illustrating a phase profile of light transmitted through a portion along line L-L′ of the pixel array  1130  of  FIG.  25   . 
     The pixel array  1130  of  FIGS.  25  to  29    may be substantially the same as the pixel array  1110  of  FIG.  16   , except that a plurality of nanophotonic microlenses  161 ,  162 ,  163 , and  164  (hereinafter, also referred to as first to fourth nanophotonic microlenses  161  to  164 ) included in a nanophotonic microlens array  160  have different shapes according to wavelengths of light sensed by corresponding pixels, unlike the nanophotonic microlens array  140  of  FIG.  16   . In  FIG.  25   , for convenience of description, the sensor substrate  110  and the filter layer  120  included in the pixel array  1130  are omitted. In describing  FIGS.  25  to  29   , descriptions that are provided in connection with  FIGS.  1  to  19    are omitted. Also, in describing  FIGS.  25  to  29   , the reference numerals of the components illustrated in  FIGS.  1  to  15    are used. 
     Referring to  FIGS.  25  to  29   , each of the plurality of nanophotonic microlenses  161 ,  162 ,  163 , and  164  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  160  may be formed such that maximum points of a plurality of convex portions of each of the plurality of nanophotonic microlenses  161 ,  162 ,  163 , and  164  are spaced apart from the respective center points of the plurality of photosensitive cells, i.e., the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d , in the first direction (y-direction), and are distributed to be closer to the center line of the DTI structure d 1 , d 2 , d 3 , or d 4  in the first direction (y-direction) than to each of the center points of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d.    
     For example, the first nanophotonic microlens  161  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  160  may be formed such that maximum points s 9 , s 10 , s 11 , and s 12  of the plurality of convex portions of the first nanophotonic microlens  161  are spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction), and are distributed closer to the center line dcl of the first DTI structure d 1  in the first direction (y-direction) than to the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d.    
     As described above, unlike the maximum points s 1 , s 2 , s 3 , and s 4  of the first nanophotonic microlens  131  of the nanophotonic microlens array  130  of  FIGS.  7  and  8   , the maximum points s 9 , s 10 , s 11 , and s 12  of the first nanophotonic microlens  161  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  160  may be distributed to be spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  all in the first direction (y-direction). 
     Referring to  FIGS.  25  to  29   , the nanophotonic microlens array  160  may include the first nanophotonic microlens  161  and the fourth nanophotonic microlens  164  respectively corresponding to the first pixel  111  and the fourth pixel  114  that sense light of the first wavelength band, which is the green light region. The first and fourth nanophotonic microlenses  161  and  164  may correspond to the first filter  121  and the fourth filter  124 , respectively. The first and fourth nanophotonic microlenses  161  and  164  may focus light on the first pixel  111  and the fourth pixel  114 , respectively. 
     In addition, the nanophotonic microlens array  160  may include the second nanophotonic microlens  162  and the third nanophotonic microlens  163 , which respectively correspond to the second pixel  112  that senses light of the second wavelength band, which is the blue light region, and the third pixel  113  that senses light of the third wavelength band, which is the red light region. The second nanophotonic microlens  162  may correspond to the second filter  122 , and the third nanophotonic microlens  163  may correspond to the third filter  123 . The second nanophotonic microlens  162  may focus light on the second pixel  112 , and the third nanophotonic microlens  163  may focus light on the third pixel  113 . 
     Here, each of the plurality of nanophotonic microlenses  161 ,  162 ,  163 , and  164  may have a plurality of convex portions, which are more convex as the wavelength band of light sensed by the corresponding pixel is shorter. For example, as illustrated in  FIG.  26   , a plurality of second convex portions of the second nanophotonic microlens  162  corresponding to the second pixel  112  that senses light of the second wavelength band, which is the blue light region, may be formed to be more convex than a plurality of first convex portions of the first nanophotonic microlens  161  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region. In addition, as illustrated in  FIG.  27   , the plurality of first convex portions of the first nanophotonic microlens  161  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region, may be formed to be more convex than a plurality of third convex portions of the third nanophotonic microlens  163  corresponding to the third pixel  113  that senses light of the third wavelength band, which is the red light region. Furthermore, a plurality of fourth convex portions of the fourth nanophotonic microlens  164  corresponding to the fourth pixel  114  that senses light of the first wavelength band, which is the green light region, may have the same shape as that of the plurality of first convex portions of the first nanophotonic microlens  161 . 
     Moreover, as illustrated in  FIGS.  25  and  28   , the plurality of convex portions of the first nanophotonic microlens  161  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  160  may be symmetrically distributed in the second direction (x-direction) with respect to the center line dcl of the first DTI structure d 1  in the first direction (y-direction). In addition, as illustrated in  FIGS.  25 ,  28   , and  29 , the plurality of convex portions of the second to fourth nanophotonic microlenses  162 ,  163 , and  164  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  160  may be symmetrically distributed in the second direction (x-direction) with respect to the center lines of the second to fourth DTI structures d 2 , d 3 , and d 4  in the first direction (y-direction), respectively. 
     In this case, as illustrated in  FIG.  30   , a plurality of second convex regions included in the phase profile of light transmitted through the second nanophotonic microlens  162  may be more convex than a plurality of first convex regions included in the phase profile of light transmitted through the first nanophotonic microlens  161 . For example, the phase change of the light transmitted through the second nanophotonic microlens  162  may be substantially greater than the phase change of the light transmitted through the first nanophotonic microlens  161 . 
     In addition, as illustrated in  FIG.  31   , a plurality of fourth convex regions included in the phase profile of light transmitted through the fourth nanophotonic microlens  164  may be more convex than a plurality of third convex regions included in the phase profile of light transmitted through the third nanophotonic microlens  163 . For example, the phase change of the light transmitted through the fourth nanophotonic microlens  164  may be substantially greater than the phase change of the light transmitted through the third nanophotonic microlens  163 . 
     In addition, as illustrated in  FIG.  32   , the plurality of first convex regions included in the phase profile of the light transmitted through the first nanophotonic microlens  161  may be more convex than the plurality of third convex regions included in the phase profile of the light transmitted through the third nanophotonic microlens  163 . 
     In addition, as illustrated in  FIG.  33   , the plurality of second convex regions included in the phase profile of the light transmitted through the second nanophotonic microlens  162  may be more convex than the plurality of fourth convex regions included in the phase profile of the light transmitted through the fourth nanophotonic microlens  164 . 
     Furthermore, the plurality of fourth convex regions included in the phase profile of the light transmitted through the fourth nanophotonic microlens  164  may have the same shape as the plurality of first convex regions included in the phase profile of the light transmitted through the first nanophotonic microlens  161 . 
     Light incident on the left peripheral region aa 2  among the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  160  is incident on the pixel array  1130  at an angle in the opposite direction to the direction of light incident on the right peripheral region aa 3 , with respect to the normal line of the pixel array  1130 . Accordingly, the first to fourth nanophotonic microlenses  161  to  164  arranged in the left peripheral region aa 2  of the nanophotonic microlens array  160  may have a shape inverted, in the first direction (y-direction), from the shape of the first to fourth nanophotonic microlens  161  to  164  arranged in the right peripheral region aa 3 . 
       FIG.  34    is a perspective view illustrating an example configuration of a pixel array  1140  included in the optical sensor  1000 , according to another example embodiment.  FIG.  35    is a plan view illustrating an example configuration of the pixel array  1140  of  FIG.  34   .  FIG.  36    is a plan view illustrating an example configuration of a first nanophotonic microlens  171  included in the pixel array  1140  of  FIG.  34   . 
     The pixel array  1140  of  FIG.  34    may be substantially the same as the pixel array  1100  of  FIG.  7   , except that the configuration of a nanophotonic microlens array  170  is different from that of the nanophotonic microlens array  130  of  FIG.  7   . In  FIG.  35   , for convenience of description, the sensor substrate  110  and the filter layer  120  included in the pixel array  1140  are omitted. In describing  FIGS.  34  to  36   , descriptions that are provided in connection with  FIGS.  1  to  15    are omitted. Also, in describing  FIGS.  34  to  36   , the reference numerals of the components illustrated in  FIGS.  1  to  15    are used. 
     Hereinafter, characteristics of a plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  (hereinafter, also referred to as first to fourth nanophotonic microlenses  171  to  174 ) of the nanophotonic microlens array  170 , which are distinguished from the configuration of the nanophotonic microlens array  130  of  FIG.  7   , will be described. 
     Referring to  FIG.  35   , the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may include a two-dimensional array of the first nanophotonic microlens  171  corresponding to the first pixel  111 , the second nanophotonic microlens  172  corresponding to the second pixel  112 , the third nanophotonic microlens  173  corresponding to the third pixel  113 , and the fourth nanophotonic microlens  174  corresponding to the fourth pixel  114 . 
     Each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may include a plurality of nanostructures NS arranged such that light transmitted through the nanophotonic microlens has a phase profile having a plurality of convex regions. The shapes, sizes (widths, heights), gaps, and arrangement of the plurality of nanostructures NS may be determined such that light immediately after passing through the first to fourth nanostructures  171  to  174  has a certain phase profile. 
     Although  FIG.  35    illustrates that each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  includes 100 nanostructures NS, the number of nanostructures NS may be less than or greater than 100. Light transmitted through the nanophotonic microlens array  170  may have substantially the same phase profile as that of the light transmitted through the nanophotonic microlens array  130  of  FIG.  7    described above with reference to  FIGS.  12  to  15   . 
     For example, the light transmitted through the first nanophotonic microlens  171  may have a phase profile in which a plurality of convex regions overlap each other, and in this case, the number of convex regions included in the phase profile of the light transmitted through the first nanophotonic microlens  171  may be equal to the number of photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  included in the first pixel  111  corresponding to the first nanophotonic microlens  171 . The plurality of convex regions in the phase profile of the light transmitted through the first nanophotonic microlens  171  may be regions distinguished from each other, and may be two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). 
     Similarly, light transmitted through each of the second to fourth nanophotonic microlenses  172  to  174  may have a phase profile in which a plurality of convex regions overlap each other. In this case, the number of convex regions in the phase profile of the light transmitted through each of the second to fourth nanophotonic microlenses  172  to  174  may be equal to the number of photosensitive cells, i.e., the number of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the number of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the number of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d , included in the pixel  112 ,  113 , or  114  corresponding to the nanophotonic microlens. 
     The plurality of nanostructures NS included in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may be two-dimensionally arranged in the first direction (y-direction) and the second direction (x-direction). For example, each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may include a plurality of rows in the first direction (y) and a plurality of columns in the second direction (x), in which the plurality of nanostructures NS are provided. 
     Any one row in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may include a plurality of nanostructures NS, the diameters of which increase, decrease, increase, and decrease in the first direction (y-direction). In this case, gaps between the plurality of nanostructures NS included in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  in the first direction (y-direction) may be constant. In addition, the nanostructure NS located at the center of any one row in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may have a diameter smaller than that of the nanostructures NS adjacent to both sides thereof in the first direction (y-direction). For example, the diameters of the nanostructures NS provided in a 1-1st DTI region da 1  including a region corresponding to the first DTI structure d 1 , in any row of the first nanophotonic microlens  171  may be smaller than the diameters of the nanostructures NS provided in a peripheral region of the 1-1st DTI region da 1  in the first direction (y-direction). 
     In addition, any one column in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may include a plurality of nanostructures NS, the diameters of which increase, decrease, increase, and decrease in the second direction (x-direction). In this case, gaps between the plurality of nanostructures NS included in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  in the second direction (x-direction) may be constant. The gaps between the plurality of nanostructures NS included in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  in the second direction (x-direction) may be equal to the gaps in the first direction (y-direction). In addition, the nanostructure NS located at the center of any one column in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may have a diameter smaller than that of the nanostructures NS adjacent to both sides thereof in the second direction (x-direction). For example, the diameters of the nanostructures NS provided in a 1-2nd DTI region da 2  including a region corresponding to the first DTI structure d 1 , in any column of the first nanophotonic microlens  171  may be smaller than the diameters of the nanostructures NS provided in a peripheral region of the 1-2nd DTI region da 2  in the second direction (x-direction). 
     The arrangement of the plurality of nanostructures NS included in the first nanophotonic microlens  171  described above may be substantially equally applied to the second to fourth nanophotonic microlenses  172  to  174 . 
     In addition, each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may include a sparse area in which a plurality of nanostructures NS having relatively small diameters are distributed, and a dense area in which a plurality of nanostructures NS having relatively large diameters are distributed. The dense area included in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may be surrounded by the sparse area. 
     For example, referring to  FIG.  36   , the first nanophotonic microlens  171  may include a dense area br surrounded by a sparse area cr. In this case, the dense area br may include a plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4  (hereinafter, also referred to as first to fourth sub-dense areas br 1  to br 4 ) spaced apart from each other by the sparse area cr. In each of the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4 , the plurality of nanostructures NS may be arranged such that the diameters thereof increases toward the center from an edge of the sub-dense area. In this case, the sub-dense areas br 1 , br 2 , br 3 , and br 4  may be surrounded by a first sparse area cr 1 . In addition, the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4  may be arranged to surround a second sparse area cr 2 . The first sparse area cr 1  may surround the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4 , and may occupy a wider region than the second sparse area cr 2  surrounded by the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4 . As described above, the sparse area cr may be formed to correspond to the center and edge portions of the first nanophotonic microlens  171 . In addition, the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4  may be symmetrically distributed with respect to a region corresponding to the first DTI structure d 1  of the first nanophotonic microlens  171 . 
     In addition, center points s 13 , s 14 , s 15 , and s 16  of the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4  may be provided in regions between the first DTI structure d 1  of the first nanophotonic microlens  171  and the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d . Accordingly, the center points s 13 , s 14 , s 15 , and s 16  of the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4  may be closer to the center of the first nanophotonic microlens  171  than to the center points c 1 , c 2 , c 3 , and c 4  of the first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d.    
     The description regarding the dense area br and the sparse area cr of the first nanophotonic microlens  171  may be substantially equally applied to the second to fourth nanophotonic microlenses  172 ,  173 , and  174 . 
     The number of sub-dense areas included in each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174  may be equal to the number of photosensitive cells included in the pixel corresponding to each of the plurality of nanophotonic microlenses  171 ,  172 ,  173 , and  174 . 
     For example, the first nanophotonic microlens  171  may include the plurality of sub-dense areas br 1 , br 2 , br 3 , and br 4 , the number of which is equal to the number of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  included in the first pixel  111 . In this case, the first pixel  111  may include four first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , and the first nanophotonic microlens  171  may include the first sub-dense area br 1 , the second sub-dense area br 2 , the third sub-dense area br 3 , and the fourth sub-dense area br 4  corresponding thereto. 
     The description regarding the number of sub-dense areas br 1 , br 2 , br 3 , and br 4  of the first nanophotonic microlens  171  may be substantially equally applied to the second to fourth nanophotonic microlenses  172 ,  173 , and  174 . 
       FIG.  37    is a plan view illustrating an example configuration of a pixel array  1150  included in the optical sensor  1000 , according to another example embodiment.  FIG.  38    is a plan view illustrating an example configuration of a first nanophotonic microlens  181  included in the pixel array  1150  of  FIG.  34   . 
     The pixel array  1150  of  FIG.  37    may be substantially the same as the pixel array  1140  of  FIG.  34   , except that the configuration of a nanophotonic microlens array  180  is different from that of the nanophotonic microlens array  170  of  FIG.  34   . In  FIG.  37   , for convenience of description, the sensor substrate  110  and the filter layer  120  included in the pixel array  1150  are omitted. In describing  FIG.  37   , descriptions that are provided in connection with  FIGS.  1  to  15  and  34  to  36    will be omitted. Also, in describing  FIG.  37   , the reference numerals of the components illustrated in  FIGS.  1  to  15    are used. 
     The configuration of the central region aa 1  (see  FIG.  6   ) of the nanophotonic microlens array  180  included in the pixel array  1150  of  FIG.  37    may be the same as that of the nanophotonic microlens array  170  included in the pixel array  1140  of  FIG.  34   . 
     According to another example embodiment, the configuration of the peripheral regions aa 2  and aa 3  (see  FIG.  6   ) of the nanophotonic microlens array  180  may be different from that of the nanophotonic microlens array  170 . However, the nanophotonic microlens array  180  may be substantially the same as the nanophotonic microlens array  170  of  FIG.  34    in that each of a plurality of nanophotonic microlenses  181 ,  182 ,  183 , and  184  (hereinafter, also referred to as first to fourth nanophotonic microlenses  181  to  184 ) arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  includes the plurality of nanostructures NS arranged such that light transmitted through each of the plurality of nanophotonic microlenses  181 ,  182 ,  183 , and  184  has a phase profile having a plurality of convex regions. Also, the nanophotonic microlens array  170  of  FIG.  34    may be substantially the same as the nanophotonic microlens array  170  of  FIG.  34    in that each of the plurality of nanophotonic microlenses  181 ,  182 ,  183 , and  184  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  includes a dense area and a sparse area, and a plurality of sub-dense areas included in the dense area are surrounded by the sparse area. 
     Hereinafter, characteristics of the plurality of nanophotonic microlenses  181 ,  182 ,  183 , and  184  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180 , which are distinguished from the configuration of the nanophotonic microlens array  170  of  FIG.  34   , will be described. 
     Referring to  FIG.  37   , each of the plurality of nanophotonic microlenses  181 ,  182 ,  183 , and  184  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  may be formed such that the center points of the plurality of sub-dense areas of each of the plurality of nanophotonic microlenses  181 ,  182 ,  183 , and  184  are spaced apart from the respective center points of the plurality of photosensitive cells, i.e., the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d , in the first direction (y-direction), and are distributed to be closer to the center line of the DTI structure in the first direction (y-direction) than to each of the center points of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d , the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d.    
     For example, referring to  FIG.  38   , the first nanophotonic microlens  181  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  may be formed such that center points s 17 , s 18 , s 19 , and s 20  of a plurality of sub-dense areas br 5 , br 6 , br 7 , and br 8 , which are spaced apart from each other by a sparse area cr 3  of the first nanophotonic microlens  181 , are spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction), and are distributed to be closer to the center line dcl of the first DTI structure d 1  in the first direction (y-direction) than to the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d.    
     As described above, unlike the center points s 13 , s 14 , s 15 , and s 16  of the plurality of sub-dense areas br 5 , br 6 , br 7 , and br 8  of the first nanophotonic microlens  171  of  FIG.  36   , the center points s 17 , s 18 , s 19 , and s 20  of the plurality of sub-dense regions br 5 , br 6 , br 7 , and br 8  of the first nanophotonic microlens  181  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  may be distributed to be spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction). 
     As illustrated in  FIG.  38   , the center points s 17 , s 18 , s 19 , and s 20  of the plurality of sub-dense areas br 5 , br 6 , br 7 , and br 8  of the first nanophotonic microlens  181  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  may be symmetrically distributed in the second direction (x-direction) with respect to the center line dcl of the first DTI structure d 1  in the first direction (y-direction). In this case, the phase profile, in the second direction (x-direction), of light transmitted through the first nanophotonic microlens  181 , which includes the center points s 17 , s 18 , s 19 , and s 20  of the plurality of sub-dense areas br 5 , br 6 , br 7 , and br 8  symmetrically arranged in the second direction (x-direction), and is arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180 , may be the same as illustrated in  FIG.  13   . 
     In addition, as the distance between the central region aa 1  of the nanophotonic microlens array  180  and the first nanophotonic microlens  181  increases, the distances between the center points s 17 , s 18 , s 19 , and s 20  of the plurality of sub-dense areas and the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction) may also increase. For example, the nanophotonic microlens array  180  may include a 1-1st nanophotonic microlens arranged at one point in the peripheral regions aa 2  and aa 3 , and a 1-2nd nanophotonic microlens arranged farther from the central region aa 1  than the 1-1st nanophotonic microlens. In this case, the distance between the center points of the plurality of sub-dense areas and the center points of the plurality of photosensitive cells in the 1-2nd nanophotonic microlens may be greater than the distance between the center points of the plurality of sub-dense areas and the center points of the plurality of photosensitive cells in the 1-1st nanophotonic microlens. Accordingly, despite the fact that the CRA of incident light increases toward the edge of the nanophotonic microlens array  180 , the phase change of the incident light may also increase to that extent, and consequently, the difference between the amount of light collected on the plurality of photosensitive cells arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  and the amount of light collected on the plurality of photosensitive cells arranged in the central region aa 1  may be minimized. 
     Similarly, each of the second to fourth nanophotonic microlenses  182  to  184  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  may be formed such that the center points of the plurality of sub-dense areas, which are spaced apart from each other by the sparse area of the nanophotonic microlens, are spaced apart from the center points of the plurality of second photosensitive cells  112   a ,  112   b ,  112   c , and  112   d , the plurality of third photosensitive cells  113   a ,  113   b ,  113   c , and  113   d , or the plurality of fourth photosensitive cells  114   a ,  114   b ,  114   c , and  114   d , in the first direction (y-direction), and are distributed to be closer to the center line of the second, third, or fourth DTI structure d 2 , d 3 , or d 4  in the first direction (y-direction) than to the center points of the plurality of corresponding photosensitive cells. 
     In addition, the plurality of convex portions of the second to fourth nanophotonic microlenses  182  to  184  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  may be symmetrically distributed in the second direction (x-direction) with respect to the center lines of the second to fourth DTI structures d 2  to d 4  in the first direction (y-direction), respectively. 
     Light transmitted through the nanophotonic microlens array  180  may have substantially the same phase profile as that of the light transmitted through the nanophotonic microlens array  140  described above with reference to  FIGS.  16  to  19   . 
     Also, light incident on the left peripheral region aa 2  among the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  180  is incident on the pixel array  1150  at an angle in the opposite direction to the direction of light incident on the right peripheral region aa 3 , with respect to the normal line of the pixel array  1150 . Accordingly, the first to fourth nanophotonic microlenses  181  to  184  arranged in the left peripheral region aa 2  of the nanophotonic microlens array  180  may have a shape inverted, in the first direction (y-direction), from the shape of the first to fourth nanophotonic microlens  181  to  184  arranged in the right peripheral region aa 3 . 
       FIG.  39    is a plan view illustrating an example configuration of a pixel array  1160  included in the optical sensor  1000 , according to another example embodiment. 
     The pixel array  1160  of  FIG.  39    may be substantially the same as the pixel array  1140  of  FIG.  34   , except that a plurality of nanophotonic microlenses  191 ,  192 ,  193 , and  194  (hereinafter, also referred to as first to fourth nanophotonic microlenses  191  to  194 ) included in a nanophotonic microlens array  190  have different shapes according to wavelengths of light sensed by corresponding pixels, unlike the nanophotonic microlens array  170  of  FIG.  34   . In  FIG.  39   , for convenience of description, the sensor substrate  110  and the filter layer  120  included in the pixel array  1160  are omitted. In describing  FIG.  39   , descriptions that are provided in connection with  FIGS.  1  to  15  and  34  to  36    will be omitted. Also, in describing  FIG.  39   , the reference numerals of the components illustrated in  FIGS.  1  to  15    are used. 
     Referring to  FIG.  39   , the nanophotonic microlens array  190  may include the first nanophotonic microlens  191  and the fourth nanophotonic microlens  194  respectively corresponding to the first pixel  111  and the fourth pixel  114  that sense light of the first wavelength band, which is the green light region. The first and fourth nanophotonic microlenses  191  and  194  may correspond to the first filter  121  and the fourth filter  124 , respectively. The first and fourth nanophotonic microlenses  191  and  194  may focus light on the first pixel  111  and the fourth pixel  114 , respectively. 
     In addition, the nanophotonic microlens array  190  may include the second nanophotonic microlens  192  corresponding to the second pixel  112  that senses light of the second wavelength band, which is the blue light region. The second nanophotonic microlens  192  may correspond to the second filter  122 . The second nanophotonic microlens  192  may focus light on the second pixel  112 . 
     Furthermore, the nanophotonic microlens array  190  may include the third nanophotonic microlens  193  corresponding to the third pixel  113  that senses light of the third wavelength band, which is the red light region. The third nanophotonic microlens  193  may correspond to the third filter  123 . The third nanophotonic microlens  193  may focus light on the third pixel  113 . 
     Here, the plurality of nanophotonic microlenses  191 ,  192 ,  193 , and  194  may include a plurality of sub-dense areas having the plurality of nanostructures NS, the density of which increases as the wavelength band of light sensed by the corresponding pixel decreases. In this case, the average diameter of the plurality of nanostructures NS included in the plurality of sub-dense areas having relatively high density may be greater than the average diameter of the plurality of nanostructures NS included in the plurality of sub-dense areas having relatively low density. 
     For example, as illustrated in  FIG.  39   , the average diameter of the plurality of nanostructures NS included in a plurality of second sub-dense areas er 5 , er 6 , er 7 , and er 8 , which are spaced apart from each other by second sparse areas cr 6  and cr 7  of the second nanophotonic microlens  192  corresponding to the second pixel  112  that senses light of the second wavelength band, which is the blue light region, may be greater than the average diameter of the plurality of nanostructures NS included in a plurality of first sub-dense areas er 1 , er 2 , er 3 , and er 4 , which are spaced apart from each other by first sparse areas cr 4  and cr 5  of the first nanophotonic microlens  191  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region. In addition, the average diameter of the plurality of nanostructures NS included in the plurality of first sub-dense areas er 1 , er 2 , er 3 , and er 4 , which are spaced apart from each other by the first sparse areas cr 4  and cr 5  of the first nanophotonic microlens  191  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region, may be greater than the average diameter of the plurality of nanostructures NS included in a plurality of third sub-dense areas er 9 , er 10 , er 11 , and er 12 , which are spaced apart from each other by third sparse areas cr 8  and cr 9  of the third nanophotonic microlens  193  corresponding to the third pixel  113  that senses light of the third wavelength band, which is the red light region. Furthermore, the average diameter of the plurality of nanostructures NS included in a plurality of fourth sub-dense areas er 13 , er 14 , er 15 , and er 16 , which are spaced apart from each other by fourth sparse areas cr 10  and cr 11  of the fourth nanophotonic microlens  194  corresponding to the fourth pixel  114  that senses light of the first wavelength band, which is the green light region, may be equal to the average diameter of the plurality of nanostructures NS included in the plurality of first sub-dense areas er 1 , er 2 , er 3 , and er 4 , which are spaced apart from each other by the first sparse areas cr 4  and cr 5  of the first nanophotonic microlens  191 . 
     Light transmitted through the nanophotonic microlens array  190  may have substantially the same phase profile as that of the light transmitted through the nanophotonic microlens array  150  described above with reference to  FIGS.  20  to  24   . 
       FIG.  40    is a plan view schematically illustrating an example configuration of a pixel array  1170  included in the optical sensor  1000 , according to another example embodiment. 
     The pixel array  1170  of  FIG.  40    may be substantially the same as the pixel array  1150  of  FIG.  37   , except that a plurality of nanophotonic microlenses  201 ,  202 ,  203 , and  204  (hereinafter, also referred to as first to fourth nanophotonic microlenses  201  to  204 ) included in a nanophotonic microlens array  200  have different shapes according to wavelengths of light sensed by corresponding pixels, unlike the nanophotonic microlens array  180  of  FIG.  37   . In  FIG.  40   , for convenience of description, the sensor substrate  110  and the filter layer  120  included in the pixel array  1170  are omitted. In describing  FIG.  40   , descriptions that are provided in connection with  FIGS.  1  to  15  and  34  to  38    will be omitted. Also, in describing  FIG.  40   , the reference numerals of the components illustrated in  FIGS.  1  to  15    are used. 
     Referring to  FIG.  40   , each of the plurality of nanophotonic microlenses  201 ,  202 ,  203 , and  204  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  200  may be formed such that the center points of corresponding ones of a plurality of sub-dense areas fr 1 , fr 2 , fr 3 , fr 4 , fr 5 , fr 6 , fr 7 , fr 8 , fr 9 , fr 10 , fr 11 , fr 12 , fr 13 , fr 14 , fr 15 , and fr 16 , which are spaced apart from each other by a sparse area cr 12 , cr 13 , cr 14 , or cr 15  of the nanophotonic microlens, are spaced apart from the center points of corresponding ones of the plurality of photosensitive cells  111   a ,  111   b ,  111   c ,  111   d ,  112   a ,  112   b ,  112   c ,  112   d ,  113   a ,  113   b ,  113   c ,  113   d ,  114   a ,  114   b ,  114   c , and  114   d  in the first direction (y-direction), respectively, and are distributed to be closer to the center line of the DTI structure in the first direction (y-direction) than to each of the center points of corresponding ones of the plurality of photosensitive cells  111   a ,  111   b ,  111   c ,  111   d ,  112   a ,  112   b ,  112   c ,  112   d ,  113   a ,  113   b ,  113   c ,  113   d ,  114   a ,  114   b ,  114   c , and  114   d.    
     For example, referring to  FIG.  40   , the first nanophotonic microlens  201  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  200  may be formed such that center points s 21 , s 22 , s 23 , and s 24  of a plurality of first sub-dense areas fr 1 , fr 2 , fr 3 , and fr 4 , which are spaced apart from each other by a first sparse area cr 12  of the first nanophotonic microlens  201 , are spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction), and are distributed to be closer to the center line dcl of the first DTI structure d 1  in the first direction (y-direction) than to the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d.    
     As described above, the center points s 21 , s 22 , s 23 , and s 24  of the plurality of first sub-dense areas fr 1 , fr 2 , fr 3 , and fr 4  of the first nanophotonic microlens  201  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  200  may be distributed to be spaced apart from the center points c 1 , c 2 , c 3 , and c 4  of the plurality of first photosensitive cells  111   a ,  111   b ,  111   c , and  111   d  in the first direction (y-direction). 
     As illustrated in  FIG.  40   , the center points s 21 , s 22 , s 23 , and s 24  of the plurality of first sub-dense areas fr 1 , fr 2 , fr 3 , and fr 4  of the first nanophotonic microlens  201  arranged in the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  200  may be symmetrically distributed in the second direction (x-direction) with respect to the center line dcl of the first DTI structure d 1  in the first direction (y-direction). 
     The description regarding the number of first sub-dense areas fr 1 , fr 2 , fr 3 , and fr 4  of the first nanophotonic microlens  201  may be substantially equally applied to the second to fourth nanophotonic microlenses  202 ,  203 , and  204 . 
     In addition, the nanophotonic microlens array  200  may include the first nanophotonic microlens  201  and the fourth nanophotonic microlens  204  respectively corresponding to the first pixel  111  and the fourth pixel  114  that sense light of the first wavelength band, which is the green light region. The first and fourth nanophotonic microlenses  201  and  204  may correspond to the first filter  121  and the fourth filter  124 , respectively. The first and fourth nanophotonic microlenses  201  and  204  may focus light on the first pixel  111  and the fourth pixel  114 , respectively. 
     In addition, the nanophotonic microlens array  200  may include the second nanophotonic microlens  202  corresponding to the second pixel  112  that senses light of the second wavelength band, which is the blue light region. The second nanophotonic microlens  202  may correspond to the second filter  122 . The second nanophotonic microlens  202  may focus light on the second pixel  112 . 
     Furthermore, the nanophotonic microlens array  200  may include the third nanophotonic microlens  203  corresponding to the third pixel  113  that senses light of the third wavelength band, which is the red light region. The third nanophotonic microlens  203  may correspond to the third filter  123 . The third nanophotonic microlens  203  may focus light on the third pixel  113 . 
     Here, the plurality of nanophotonic microlenses  201 ,  202 ,  203 , and  204  may include a plurality of sub-dense areas having the plurality of nanostructures NS, the density of which increases as the wavelength band of light sensed by the corresponding pixel decreases. In this case, the average diameter of the plurality of nanostructures NS included in the plurality of sub-dense areas having relatively high density may be greater than the average diameter of the plurality of nanostructures NS included in the plurality of sub-dense areas having relatively low density. 
     For example, as illustrated in  FIG.  40   , the average diameter of the plurality of nanostructures NS included in a plurality of second sub-dense areas fr 5 , fr 6 , fr 7 , and fr 8  of the second nanophotonic microlens  202  corresponding to the second pixel  112  that senses light of the second wavelength band, which is the blue light region, may be greater than the average diameter of the plurality of nanostructures NS included in the plurality of first sub-dense areas fr 1 , fr 2 , fr 3 , and fr 4  of the first nanophotonic microlens  201  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region. In addition, the average diameter of the plurality of nanostructures NS included in the plurality of first sub-dense areas fr 1 , fr 2 , fr 3 , and fr 4  of the first nanophotonic microlens  201  corresponding to the first pixel  111  that senses light of the first wavelength band, which is the green light region, may be greater than the average diameter of the plurality of nanostructures NS included in a plurality of third sub-dense areas fr 9 , fr 10 , fr 11 , and fr 12  of the third nanophotonic microlens  203  corresponding to the third pixel  113  that senses light of the third wavelength band, which is the red light region. Furthermore, the average diameter of the plurality of nanostructures NS included in a plurality of fourth sub-dense areas fr 13 , fr 14 , fr 15 , and fr 16  of the fourth nanophotonic microlens  204  corresponding to the fourth pixel  114  that senses light of the first wavelength band, which is the green light region, may be equal to the average diameter of the plurality of nanostructures NS included in the plurality of first sub-dense areas fr 1 , fr 2 , fr 3 , and fr 4  of the first nanophotonic microlens  201 . 
     Light transmitted through the nanophotonic microlens array  200  may have substantially the same phase profile as that of the light transmitted through the nanophotonic microlens array  160  described above with reference to  FIGS.  25  to  33   . 
     Light incident on the left peripheral region aa 2  among the peripheral regions aa 2  and aa 3  of the nanophotonic microlens array  200  is incident on the pixel array  1170  at an angle in the opposite direction to the direction of light incident on the right peripheral region aa 3 , with respect to the normal line of the pixel array  1170 . Accordingly, the first to fourth nanophotonic microlenses  201  to  204  arranged in the left peripheral region aa 2  of the nanophotonic microlens array  200  may have a shape inverted, in the first direction (y-direction), from the shape of the first to fourth nanophotonic microlens  201  to  204  arranged in the right peripheral region aa 3 . 
       FIG.  41    is a block diagram illustrating an electronic device  1801  including an image sensor, according to an example embodiment. 
     Referring to  FIG.  41   , in a network environment  1899 , the electronic device  1801  may communicate with another electronic device  1802  through a first network  1898  (e.g., a short-range wireless communication network) or may communicate with another electronic device  1804  and/or a server  1808  through a second network  1899  (e.g., a long-range wireless communication network). The electronic device  1801  may communicate with the electronic device  1804  through the server  1808 . The electronic device  1801  may include a processor  1820 , a memory  1830 , an input device  1850 , an audio output device  1855 , a display device  1860 , an audio module  1870 , a sensor module  1876 , an interface  1877 , a haptic module  1879 , the camera module  1880 , a power management module  1888 , a battery  1889 , a communication module  1890 , a subscriber identification module  1896 , and/or an antenna module  1897 . Some (e.g., the display device  1860 ) of these components may be omitted or other components may be additionally included in the electronic device  1801 . Some of these components may be implemented in one integrated circuit. For example, the sensor module  1876  (e.g., a fingerprint sensor, an iris sensor, an illuminance sensor) may be embedded in the display device  1860  (e.g., a display) to be implemented. 
     The processor  1820  may execute software (e.g., programs  1840 ) to control one or more other components (e.g., hardware or software components) of the electronic device  1801  connected to the processor  1820 , and may perform a variety of data processing or operations. As part of the data processing or operations, the processor  1820  may load commands and/or data received from other components (e.g., the sensor module  1876 , the communication module  1890 ) into a volatile memory  1832 , process the commands and/or data stored in the volatile memory  1832 , and store result data in a nonvolatile memory  1834 . The processor  1820  may include a main processor  1821  (e.g., a central processing unit, an application processor) and an auxiliary processor  1823  (e.g., a graphics processing unit, an image signal processor, a sensor hub processor, a communication processor) that may operate independently of or together with the main processor  1821 . The auxiliary processor  1823  may consume less power than the main processor  1821 , and may perform a specialized function. 
     The auxiliary processor  1823  may control functions and/or states related to some components (e.g., the display device  1860 , the sensor module  1876 , the communication module  1890 ) of the electronic device  1801 , on behalf of the main processor  1821  while the main processor  1821  is in an inactive (e.g., sleep) state, or with the main processor  1821  while the main processor  1821  is in an active (e.g., application execution) state. The auxiliary processor  1823  (e.g., an image signal processor, a communication processor) may be implemented as part of other functionally relevant components (e.g., the camera module  1880 , the communication module  1890 ). 
     The memory  1830  may store a variety of data required by components (e.g., the processor  1820 , the sensor module  1876 ) of the electronic device  1801 . The data may include, for example, software (e.g., programs  1840 , etc.) and input data and/or output data for commands related thereto. The memory  1830  may include the volatile memory  1832  and/or the nonvolatile memory  1834 . 
     The programs  1840  may be stored as software in the memory  1830 , and may include an operating system  1842 , middleware  1844 , and/or an application  1846 . 
     The input device  1850  may receive commands and/or data to be used for the components (e.g., the processor  1820 ) of the electronic device  1801  from the outside (e.g., a user) of the electronic device  1801 . The input device  1850  may include a remote controller, a microphone, a mouse, a keyboard, and/or a digital pen (e.g., a stylus pen). 
     The audio output device  1855  may output an audio signal to the outside of the electronic device  1801 . The audio output device  1855  may include a speaker and/or a receiver. The speaker may be used for general purposes such as multimedia playback or recording playback, and the receiver may be used to receive an incoming call. The receiver may be combined as part of the speaker or may be implemented as an independent separate device. 
     The display device  1860  may visually provide information to the outside of the electronic device  1801 . The display device  1860  may include a display, a hologram device, or a projector, and a control circuit for controlling the devices. The display device  1860  may include a touch circuitry configured to detect a touch or a sensor circuitry (e.g., a pressure sensor) configured to measure a strength of a force generated by the touch. 
     The audio module  1870  may convert a sound into an electrical signal or vice versa. The audio module  1870  may obtain a sound through the input device  1850  or may output the sound through the audio output device  1855  and/or a speaker and/or headphones of another electronic device (e.g., the electronic device  1802 ) directly or wirelessly connected to the electronic device  1801 . 
     The sensor module  1876  may detect an operating state (e.g., power, temperature) of the electronic device  1801  or an external environment state (e.g., a user state), and may generate an electrical signal and/or a data value corresponding to the detected state. The sensor module  1876  may include a gesture sensor, a gyro sensor, a barometric sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, and/or an illuminance sensor. 
     The interface  1877  may support one or more designated protocols, which may be used to directly or wirelessly connect the electronic device  1801  to another electronic device (e.g., the electronic device  1802 ). The interface  1877  may include a high-definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, and/or an audio interface. 
     A connection terminal  1878  may include a connector through which the electronic device  1801  may be physically connected to another electronic device (e.g., the electronic device  1802 ). The connection terminal  1878  may include an HDMI connector, a USB connector, an SD card connector, and/or an audio connector (e.g., a headphone connector). 
     The haptic module  1879  may convert an electrical signal into a mechanical stimulus (e.g., vibration, movement, etc.) or an electrical stimulus that a user may perceive through a tactile or motor sensations. The haptic module  1879  may include a motor, a piezoelectric element, and/or an electrical stimulation device. 
     The camera module  1880  may capture a still image or a moving image. The camera module  1880  may include a lens assembly including one or more lenses, image sensors, image signal processors, and/or flashes. A lens assembly included in the camera module  1880  may collect light emitted from an object to be image-captured. 
     The power management module  1888  may manage power supplied to the electronic device  1801 . The power management module  1888  may be implemented as part of a power management integrated circuit (PMIC). 
     The battery  1889  may supply power to components of the electronic device  1801 . The battery  1889  may include a non-rechargeable primary cell, a rechargeable secondary cell, and/or a fuel cell. 
     The communication module  1890  may support establishment a direct (wired) communication channel and/or a wireless communication channel between the electronic device  1801  and other electronic devices (e.g., the electronic devices  1802  and  1804 , the server  1808 ) and communication through the established communication channel. The communication module  1890  may operate independently of the processor  1820  (e.g., an application processor), and may include one or more communication processors supporting direct communication and/or wireless communication. The communication module  1890  may include a wireless communication module  1892  (e.g., a cellular communication module, a short-range wireless communication module, a global navigation satellite system (GNSS) communication module) and/or a wired communication module  1894  (e.g., a local area network (LAN) communication module, a power line communication module). The corresponding communication module among these communication modules may communicate with other electronic devices through the first network  1898  (e.g., a short-range communication network such as Bluetooth, Wi-Fi Direct, or Infrared Data Association (IrDA)) or the second network  1899  (e.g., a long-range communication network such as a cellular network, the Internet, or a computer network (a LAN, a wide area network (WAN))). These various types of communication modules may be integrated into a single component (e.g., a single chip, etc.) or may be implemented as a plurality of separate components (e.g., a plurality of chips). The wireless communication module  1892  may identify and authenticate the electronic device  1801  within a communication network such as the first network  1898  and/or the second network  1899  by using subscriber information (e.g., an international mobile subscriber identifier (IMSI)) stored in the subscriber identification module  1896 . 
     The antenna module  1897  may transmit or receive a signal and/or power to or from the outside (e.g., other electronic devices). An antenna may include a radiator made of a conductive pattern formed on a substrate (e.g., a printed circuit board (PCB)). The antenna module  1897  may include one or more antennas. When a plurality of antennas is included, the communication module  1890  may select an antenna suitable for a communication scheme used in a communication network such as the first network  1898  and/or the second network  1899 , from among the plurality of antennas. A signal and/or power may be transmitted or received between the communication module  1890  and other electronic devices through the selected antenna. In addition to the antenna, other components (e.g., a radio-frequency integrated circuit (RFIC)) may be included as part of the antenna module  1897 . 
     Some of the components may be connected to each other and exchange signals (e.g., commands, data) through a communication method between peripheral devices (e.g., a bus, a general-purpose input and output (GPIO), a serial peripheral interface (SPI), a mobile industry processor interface (MIPI)). 
     Commands or data may be transmitted or received between the electronic device  1801  and the external electronic device  1804  through the server  1808  connected to the second network  1899 . The other electronic devices  1802  and  1804  may be of a type that is the same as or different from the electronic device  1801 . All or some of the operations executed by the electronic device  1801  may be executed by one or more of the other electronic devices  1802 ,  1804 , and  1808 . For example, when the electronic device  1801  is required to perform a certain function or service, the electronic device  1801  may request one or more other electronic devices to perform some or all of the function or service instead of executing the function or service by itself. The one or more other electronic devices that have received the request may execute an additional function or service related to the request, and may transmit a result of the execution to the electronic device  1801 . To this end, cloud computing, distributed computing, and/or client-server computing technologies may be used. 
       FIG.  42    is a block diagram schematically illustrating the camera module  1880  illustrated in  FIG.  41   . 
     Referring to  FIG.  42   , the camera module  1880  may include the lens assembly  1910 , a flash  1920 , the optical sensor  1000  (see  FIG.  1   ), an image stabilizer  1940 , a memory  1950  (e.g., a buffer memory), and/or the image signal processor  1960 . The lens assembly  1910  may collect light emitted from an object to be image-captured. The camera module  1880  may include a plurality of lens assemblies  1910 , and in this case, the camera module  1880  may be a dual camera, a 360-degree camera, or a spherical camera. Some of the plurality of lens assemblies  1910  may have the same lens attributes (e.g., an angle of view, a focal length, autofocus, F Number, optical zoom, etc.) or different lens attributes. The lens assembly  1910  may include a wide-angle lens or a telephoto lens. 
     The flash  1920  may emit light used to enhance light emitted or reflected from the object. The flash  1920  may include one or more light-emitting diodes (e.g., red-green-blue (RGB) LEDs, white LEDs, infrared LEDs, ultraviolet LEDs), and/or a xenon lamp. The optical sensor  1000  may be the optical sensor described above with reference to  FIG.  1   , and may obtain an image corresponding to an object by converting light emitted or reflected from the object and transmitted through the lens assembly  1910  into an electrical signal. The optical sensor  1000  may include one or more sensors selected from image sensors having different attributes, such as an RGB sensor, a black and white (BW) sensor, an IR sensor, or a UV sensor. Each of the sensors included in the optical sensor  1000  may be implemented as a CCD sensor and/or a CMOS sensor. 
     The image stabilizer  1940  may move one or more lenses included in the lens assembly  1910  or the optical sensor  1000  in a particular direction in response to movement of the camera module  1980  or the electronic device  1801  including the same, or may control an operating characteristic of the optical sensor  1000  (e.g., adjustment of read-out timing) such that a negative effect due to movement is compensated for. The image stabilizer  1940  may detect movement of the camera module  1880  or the electronic device  1801  by using a gyro sensor (not shown) or an acceleration sensor (not shown) arranged inside or outside the camera module  1880 . The image stabilizer  1940  may be implemented optically. 
     In the memory  1950 , some or all of the data obtained through the optical sensor  1000  may be stored for the next image processing operation. For example, when a plurality of images are obtained at high speed, the obtained original data (e.g., Bayer-patterned data, high-resolution data) may be stored in the memory  1950  and only a low-resolution image is displayed, and then the original data of a selected image (e.g., by a user selection) may be transmitted to the image signal processor  1960 . The memory  1950  may be integrated into the memory  1830  of the electronic device  1801  or may be configured as a separate memory that operates independently. 
     The image signal processor  1960  may perform one or more image processes on an image obtained through the optical sensor  1000  or image data stored in the memory  1950 . The one or more image processes may include depth map generation, three-dimensional modeling, panorama generation, feature point extraction, image synthesis, and/or image compensation (e.g., noise reduction, resolution adjustment, brightness adjustment, blurring, sharpening, softening). The image signal processor  1960  may perform control (e.g., exposure time control, or read-out timing control) of components (e.g., the optical sensor  1000 ) included in the camera module  1880 . An image processed by the image signal processor  1960  may be stored again in the memory  1950  for further processing or may be provided to external components (e.g., the memory  1830 , the display device  1860 , the electronic device  1802 , the electronic device  1804 , the server  1808 ) of the camera module  1880 . The image signal processor  1960  may be integrated into the processor  1820  or may be configured as a separate processor that operates independently of the processor  1820 . When the image signal processor  1960  is configured as a processor separate from the processor  1820 , an image processed by the image signal processor  1960  may be displayed through the display device  1860  after further image processing by the processor  1820 . 
     The electronic device  1801  may include a plurality of camera modules  1880  having respective different attributes or functions. In this case, one of the plurality of camera modules  1880  may be a wide-angle camera, and the other may be a telephoto camera. Similarly, one of the plurality of camera modules  1880  may be a front camera, and the other may be a rear camera. 
       FIGS.  43  to  52    are diagrams illustrating various examples of electronic devices including optical sensors according to various embodiments. 
     The optical sensor  1000  (see  FIG.  1   ) according to various example embodiments may be applied to a mobile phone or smart phone  2000  illustrated in  FIG.  43   , a tablet or smart tablet  2100  illustrated in  FIG.  44   , a digital camera or camcorder  2200  illustrated in  FIG.  45   , a notebook computer  2300  illustrated in  FIG.  46   , or a television or smart television  2400  illustrated in  FIG.  47   . For example, the smart phone  2000  or the smart tablet  2100  may include a plurality of high-resolution cameras each equipped with a high-resolution optical sensor. Depth information of objects in an image may be extracted, out-focusing of an image may be adjusted, or objects in an image may be automatically identified, by using the high-resolution cameras. 
     Also, the optical sensor  1000  may be applied to a smart refrigerator  2500  illustrated in  FIG.  48   , a security camera  2600  illustrated in  FIG.  49   , a robot  2700  illustrated in  FIG.  50   , a medical camera  2800  illustrated in  FIG.  51   . For example, the smart refrigerator  2500  may automatically recognize food in the refrigerator by using the optical sensor, and inform a user of the presence or absence of particular food, the type of food being stored or released, and the like, through a smart phone. The security camera  2600  may provide an ultra-high resolution image and may recognize an object or a person in an image even in a dark environment, by using high sensitivity. The robot  2700  may be deployed in a disaster or industrial site which cannot be directly accessed by a human, and provide a high-resolution image. The medical camera  2800  may provide a high-resolution image for diagnosis or surgery, and may dynamically adjust its field of view. 
     Also, the optical sensor  1000  may be applied to a vehicle  2900  as illustrated in  FIG.  52   . The vehicle  2900  may include a plurality of vehicle cameras  2910 ,  2920 ,  2930 , and  2940  arranged at various positions. Each of the vehicle cameras  2910 ,  2920 ,  2930 , and  2940  may include an optical sensor according to an example embodiment. The vehicle  2900  may provide various pieces of information about the inside or the surroundings of the vehicle  2900  to a driver by using the plurality of vehicle cameras  2910 ,  2920 ,  2930 , and  2940 , and may provide information required for autonomous driving by automatically recognizing an object or a person in an image. 
     According to various example embodiments, provided are an optical sensor including a nanophotonic microlens array having a structure configured to reduce the amount of incident light collected on the center of a DTI structure included in each of a plurality of pixels of a sensor substrate while implementing an autofocusing (AF) technique, and an electronic device including the optical sensor. 
     According to various example embodiments, an AF technique may be implemented by using a single nanophotonic microlens in which a plurality of convex lenses overlap each other, and the amount of incident light collected at the center of a DTI structure included in each of the plurality of pixels of the sensor substrate may be reduced. 
     According to various example embodiments, provided are an optical sensor including a nanophotonic microlens array configured to change a traveling direction of incident light, which is incident on an edge of the optical sensor at a high CRA to improve the sensitivity of a sensor substrate including a plurality of pixels, and an electronic device including the optical sensor. 
     It should be understood that example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example embodiment should typically be considered as available for other similar features or aspects in other embodiments. While example embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims, and their equivalents.