PATENT DOCUMENT

Publication Number: US-11543235-B2
Application Number: US-202117219779-A
Country: US
Kind Code: B2

Title: Hybrid interferometric and scatterometric sensing using in-plane sensors

Abstract:
An optical sensor system including a semiconductor substrate; a self-mixing interferometry (SMI) sensor formed on the semiconductor substrate and including a semiconductor laser having a resonant cavity; and an array of photodetectors formed on the semiconductor substrate. The SMI sensor is configured to generate an SMI signal responsive to a retro-reflection of electromagnetic radiation emitted by the semiconductor laser and received into the resonant cavity. The array of photodetectors is configured to generate a set of angular-resolved scatter signals responsive to a scatter of the electromagnetic radiation emitted by the semiconductor laser.

Claims:
What is claimed is: 
     
       1. An optical sensor system, comprising:
 a semiconductor substrate; 
 a self-mixing interferometry (SMI) sensor formed on the semiconductor substrate and including a semiconductor laser having a resonant cavity; and 
 an array of photodetectors formed on the semiconductor substrate; wherein, 
 the SMI sensor is configured to generate an SMI signal responsive to a retro-reflection of electromagnetic radiation emitted by the semiconductor laser and received into the resonant cavity; and 
 the array of photodetectors is configured to generate a set of angular-resolved scatter signals responsive to a scatter of the electromagnetic radiation emitted by the semiconductor laser. 
 
     
     
       2. The optical sensor system of  claim 1 , wherein the SMI sensor and the array of photodetectors share a subset of epitaxial layers formed on the semiconductor substrate. 
     
     
       3. The optical sensor system of  claim 1 , wherein:
 a set of trenches electrically separate photodetectors in the array of photodetectors. 
 
     
     
       4. The optical sensor system of  claim 3 , further comprising:
 a set of cathodes for the array of photodetectors, the set of cathodes disposed in the set of trenches. 
 
     
     
       5. The optical sensor system of  claim 4 , further comprising:
 a set of anodes for the array of photodetectors, the set of anodes disposed on the array of photodetectors; wherein, 
 the set of cathodes is oriented in a first set of parallel directions; 
 the set of anodes is oriented in a second set of parallel directions; and 
 the second set of parallel directions is orthogonal to the first set of parallel directions. 
 
     
     
       6. The optical sensor system of  claim 1 , further comprising:
 an array of SMI sensors formed on the semiconductor substrate; wherein, 
 the SMI sensor is a first SMI sensor in the array of SMI sensors; and 
 the array of photodetectors is provided by additional SMI sensors in the array of SMI sensors. 
 
     
     
       7. An optical sensor system, comprising:
 a wafer-integrated array of semiconductor devices, including,
 a semiconductor laser; and 
 a set of resonant-cavity photodetectors (RCPDs); 
 
 an optical subsystem configured to direct a retro-reflection of electromagnetic radiation emitted by the semiconductor laser toward an RCPD in the set of RCPDs, and configured to direct an angular-resolved scatter of the electromagnetic radiation emitted by the semiconductor laser toward a subset or all RCPDs in the set of RCPDs. 
 
     
     
       8. The optical sensor system of  claim 7 , wherein all of the RCPDs in the set of RCPDs are in-plane. 
     
     
       9. The optical sensor system of  claim 7 , wherein a first RCPD is integrated or stacked with the semiconductor laser. 
     
     
       10. The optical sensor system of  claim 7 , wherein:
 the RCPD in the set of RCPDs is a first RCPD; and 
 the optical subsystem provides confocal imaging for,
 the first RCPD; and 
 a second RCPD in a subset of RCPDs. 
 
 
     
     
       11. The optical sensor system of  claim 7 , wherein:
 the RCPD in the set of RCPDs is a first RCPD; and 
 the optical subsystem provides non-confocal imaging for,
 the first RCPD; and 
 a second RCPD in a subset of RCPDs. 
 
 
     
     
       12. The optical sensor system of  claim 7 , wherein the optical subsystem comprises:
 a telecentric-confocal imaging system positioned apart from the wafer-integrated array of semiconductor devices in an electromagnetic radiation emission path of the semiconductor laser, and in a set of electromagnetic radiation reception paths of the set of RCPDs. 
 
     
     
       13. The optical sensor system of  claim 7 , wherein the optical subsystem comprises:
 a set of on-chip lenses disposed on the semiconductor laser and the set of RCPDs; and 
 a confocal imaging system positioned apart from the wafer-integrated array of semiconductor devices, in an electromagnetic radiation emission path of the semiconductor laser, and in a set of electromagnetic radiation reception paths of the set of RCPDs. 
 
     
     
       14. The optical sensor system of  claim 13 , wherein the optical subsystem comprises:
 an optical beam splitter positioned in the electromagnetic radiation emission path of the semiconductor laser. 
 
     
     
       15. The optical sensor system of  claim 7 , wherein:
 the wafer-integrated array of semiconductor devices is attached to a semiconductor wafer; and 
 the semiconductor laser is flip-chip bonded to the semiconductor wafer, over the RCPD to which the retro-reflection is directed. 
 
     
     
       16. An electronic device, comprising:
 a semiconductor substrate; 
 a set of semiconductor devices formed on the semiconductor substrate; and 
 a processor configured to,
 operate a first semiconductor device in the set of semiconductor devices to emit electromagnetic radiation from a resonant cavity of the first semiconductor device; 
 determine a set of parameters of a self-mixing interferometry (SMI) signal generated as a result of a self-mixing of electromagnetic radiation within the resonant cavity; 
 contemporaneously with operating the first semiconductor device, sense a scatter of the emitted electromagnetic radiation using a subset of semiconductor devices in the set of semiconductor devices; and 
 characterize at least one of an environment of the electronic device, or a relationship between the electronic device and the environment, using the determined set of parameters of the SMI signal and the sensed scatter. 
 
 
     
     
       17. The electronic device of  claim 16 , wherein:
 the environment of the electronic device comprises a surface; and 
 the processor is configured to characterize the environment of the electronic device by,
 determining, using the set of parameters of the SMI signal, at least one of a speckle, a roughness, or a texture of the surface; and 
 determining a power spectral density of the surface using the sensed scatter. 
 
 
     
     
       18. The electronic device of  claim 16 , wherein:
 the electronic device is a wearable device; 
 the first semiconductor device has a different optical focus than at least a second semiconductor device in the subset of semiconductor devices; 
 the environment of the electronic device comprises a body part of a user of the electronic device; and 
 the processor is configured to characterize the environment of the electronic device by determining at least one biometric feature of the user. 
 
     
     
       19. The electronic device of  claim 16 , wherein:
 the environment of the electronic device comprises air; and 
 the processor is configured to characterize the environment of the electronic device by,
 determining a particle speed using the set of parameters of the SMI signal; and 
 determining a particle size using the sensed scatter. 
 
 
     
     
       20. The electronic device of  claim 16 , wherein:
 the environment of the electronic device comprises a surface; 
 the processor is configured to characterize the relationship between the electronic device and the environment of the electronic device by,
 characterizing a high speed movement of the electronic device with respect to the surface responsive to at least a sensed self-mixing; and 
 characterizing a low speed movement of the electronic device with respect to the surface responsive to at least the sensed scatter; and 
 
 the high speed movement and the low speed movement are distinguished by a threshold speed of movement. 
 
     
     
       21. An optical sensor system, comprising:
 a semiconductor substrate; 
 an external photon-mixing sensor formed on the semiconductor substrate and including,
 a semiconductor laser; and 
 a photon-mixing detector; 
 
 an array of photodetectors formed on the semiconductor substrate; wherein, 
 the external photon-mixing sensor is configured to generate a field-based coherent scatterometry signal responsive to a combination of electromagnetic radiation emitted by the semiconductor laser and a portion of the emitted electromagnetic radiation that is backscattered to the photo-mixing detector; and 
 the array of photodetectors is configured to generate a set of intensity-based scatterometry signals responsive to a backscatter of the electromagnetic radiation emitted by the semiconductor laser. 
 
     
     
       22. The optical sensor system of  claim 21 , wherein the semiconductor laser, the photon-mixing detector, and the array of photodetectors share a subset of epitaxial layers formed on the semiconductor substrate. 
     
     
       23. The optical sensor system of  claim 21 , further comprising:
 an optical subsystem configured to,
 direct a first portion of the electromagnetic radiation emitted by the semiconductor laser to the photon-mixing detector; and 
 direct a second portion of a backscatter of the emitted electromagnetic radiation to the photon-mixing detector.

Description:
FIELD 
     The described embodiments generally relate to optical sensing and, more particularly, to devices that may be used for both interferometric and scatterometric optical sensing. 
     BACKGROUND 
     Coherent optical sensing, including Doppler velocimetry and heterodyning, can be used to obtain spatial information for a target. Example targets include objects, surfaces, particles, and so on. Example spatial information includes presence, distance, velocity, size, surface properties, particle count, and so on. Coherent optical sensing can sometimes be used to obtain spatial information for a target with optical wavelength resolution, at quantum limit signal levels, and with considerably lower photon energy than time-of-flight optical sensing methods. Coherent optical sensing can also limit interference from external aggressors such as ambient light or light generated by light sources of other optical sensing systems. 
     Semiconductor lasers integrated with wafer-level or wafer-bonded photodetectors enable coherent optical sensing using a monolithic sensor structure. For example, a semiconductor laser may generate and emit electromagnetic radiation from a resonant cavity of the semiconductor laser, receive returned (e.g., reflected or scattered) electromagnetic radiation back into the resonant cavity, self-mix the generated and returned electromagnetic radiation within the resonant cavity, and produce a self-mixing interferometry (SMI) signal that can be used to determine spatial information for a target. However, due to the retro-reflective nature of the SMI optical path, a likely angular incoherence of backscattered electromagnetic radiation, a likely small optical aperture and field of view of the semiconductor laser, and a possible high absorption of received electromagnetic radiation by the target, only a small amount of the electromagnetic radiation emitted by the semiconductor laser may be returned to the semiconductor laser&#39;s resonant cavity (i.e., the optical power of the returned electromagnetic radiation may be a small fraction of the optical power of the emitted electromagnetic radiation (sometimes less than 1 parts-per-million (ppm)). 
     In demanding sensing applications, such as particulate matter detection, surface profiling, and so on, the low optical power of electromagnetic radiation returned to a semiconductor laser&#39;s resonant cavity, along with the presence of noise, makes it difficult to make accurate or high resolution characterizations of a device&#39;s environment and/or the relationship of a device to its environment. 
     SUMMARY 
     Embodiments of the systems, devices, methods, and apparatus described in the present disclosure employ a combination of interferometric and scatterometric sensing techniques. Both interferometric sensors (e.g., SMI sensors) and angular-resolved scatterometric sensors may be formed on (or attached to) a shared substrate (e.g., a semiconductor substrate, or die). In many embodiments, the emission and sensing of electromagnetic radiation may be performed in-plane. The scatterometric sensors may receive much of the electromagnetic radiation that is emitted by an SMI sensor, returned from a target, but not received back into the resonant cavity of the SMI sensor. Not only does the addition of the scatterometric sensors increase the signal-to-noise ratio (SNR) of an optical sensing system as a whole, but it may enable a more accurate or higher resolution capture of spatial information from slow-moving or stationary targets, sparse targets (e.g., a low density of particles in air), and so on. 
     In a first aspect, the present disclosure describes an optical sensor system. The optical sensor system may include a semiconductor substrate, an SMI sensor formed on the semiconductor substrate and including a semiconductor laser having a resonant cavity, and an array of photodetectors formed on the semiconductor substrate. The SMI sensor may be configured to generate an SMI signal responsive to a retro-reflection of electromagnetic radiation emitted by the semiconductor laser and received into the resonant cavity. The array of photodetectors may be configured to generate a set of angular-resolved scatter signals responsive to a scatter of the electromagnetic radiation emitted by the semiconductor laser. 
     In a second aspect, the present disclosure describes another optical sensor system. The optical sensor system may include a wafer-integrated array of semiconductor devices, including a semiconductor laser and a set of resonant-cavity photodetectors (RCPDs). The optical sensor system may also include an optical subsystem configured to direct a retro-reflection of electromagnetic radiation emitted by the semiconductor laser toward an RCPD in the set of RCPDs. The optical subsystem may also be configured to direct an angular-resolved scatter of the electromagnetic radiation emitted by the semiconductor laser toward a subset of RCPDs in the set of RCPDs. 
     In a third aspect, the present disclosure describes an electronic device. The electronic device may include a semiconductor substrate, a set of semiconductor devices formed on the semiconductor substrate, and a processor. The processor may be configured to operate a first semiconductor device in the set of semiconductor devices to emit electromagnetic radiation from a resonant cavity of the first semiconductor device; determine a set of parameters of an SMI signal generated as a result of a self-mixing of electromagnetic radiation within the resonant cavity; contemporaneously with operating the first semiconductor device, sense a scatter of the emitted electromagnetic radiation using a subset of semiconductor devices in the set of semiconductor devices; and characterize at least one of an environment of the electronic device, or a relationship between the electronic device and the environment, using the determined set of parameters of the self-mixing interferometry signal and the sensed scatter. 
     In a fourth aspect, the present disclosure describes an optical sensor system. The optical sensor system may include a semiconductor substrate, an external photon-mixing sensor formed on the semiconductor substrate, and an array of photodetectors formed on the semiconductor substrate. The external photon-mixing sensor may include a semiconductor laser and a photon-mixing detector. The external photon-mixing sensor may be configured to generate a field-based coherent scatterometry signal responsive to a combination of electromagnetic radiation emitted by the semiconductor laser and a portion of the emitted electromagnetic radiation that is backscattered to the photo-mixing detector. The array of photodetectors may be configured to generate a set of intensity-based scatterometry signals responsive to a backscatter of the electromagnetic radiation emitted by the semiconductor laser. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG.  1    shows an example plan view of an optical sensor system; 
         FIG.  2    shows an example elevation of an optical sensor system including a wafer-integrated array of semiconductor devices; 
         FIG.  3    shows an optical sensor system including a telecentric-confocal imaging system; 
         FIG.  4    shows an optical sensor system including an on-chip lens (OCL)-confocal imaging system; 
         FIG.  5 A  shows an optical sensor system including a beam-splitting and non-confocal imaging system; 
         FIG.  5 B  shows an optical sensor system including a beam combiner for external photon mixing; 
         FIG.  6 A  shows an example elevation of an optical sensor system having an array of semiconductor devices formed on a semiconductor substrate; 
         FIG.  6 B  shows a representative plan view of some of the anode routings shown in  FIG.  6 A ; 
         FIG.  7 A  shows an example elevation of another optical sensor system having an array of semiconductor devices formed on a semiconductor substrate; 
         FIG.  7 B  shows a representative plan view of some of the cathode and anode routings shown in  FIG.  7 A ; 
         FIG.  8    shows an example elevation of another optical sensor system having an array of semiconductor devices formed on a semiconductor substrate; 
         FIG.  9 A  shows an optical sensor system in which one or more of the semiconductor devices are SMI sensors with integrated photodetectors, and other semiconductor devices are RCPDs with additional integrated photodetectors; 
         FIG.  9 B  shows an optical sensor system in which all of the semiconductor devices are SMI sensors with integrated photodetectors; 
         FIG.  9 C  shows an optical sensor system similar to the optical sensor system described with reference to  FIG.  9 A , but instead of each of the semiconductor devices having an integrated photodetector grown between the semiconductor substrate and the resonant cavity of a semiconductor device, a photodetector is grown above a resonant cavity of an SMI sensor; 
         FIG.  10    shows an optical sensor system in which some of its semiconductor devices are formed on a semiconductor substrate, using a common process, and one or more other semiconductor devices are picked, placed, and soldered onto the semiconductor substrate; 
         FIG.  11    shows a method of operating a set of semiconductor devices to contemporaneously obtain interferometric and scatterometric measurements; 
         FIG.  12    shows an example use of an optical sensor system to characterize a quality of a surface; 
         FIG.  13 A  shows an alternative embodiment of the optical sensor system shown in  FIG.  12   , with a lateral offset between the optical focuses of different sensors; 
         FIG.  13 B  shows an alternative embodiment of the optical sensor system shown in  FIG.  1   , with a combined lateral and horizontal offset between the optical focuses of different sensors; 
         FIG.  14    shows an example use of an optical sensor system to characterize particles or air quality within an environment; 
         FIGS.  15 A and  15 B  show example uses of an optical sensor system to characterize a relationship between an electronic device that carries the optical sensor system and a surface; 
         FIGS.  16 A and  16 B  show an example of a device (an electronic device) that includes an optical sensor system; 
         FIGS.  17 A and  17 B  show another example of a device (an electronic device) that includes an optical sensor system; 
         FIG.  18    shows an example of a mouse (an electronic device) that includes an optical sensor system; and 
         FIG.  19    shows an example electrical block diagram of an electronic device. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The following description relates to optical sensor systems having both interferometric sensors (e.g., SMI sensors) and angular-resolved scatterometric sensors. All of the sensors may be formed on (or attached to) a shared substrate. For example, the sensors may be integrated on a shared wafer. In many embodiments, the resonant cavities of semiconductor lasers and the resonant cavities of RCPDs may be in-plane. In some embodiments, both SMI sensors and RCPDs may be formed on a shared substrate using a shared process, and may share part or all of the same set of epitaxial layers (e.g., the SMI sensors and RCPDs may be co-grown). However, in some embodiments, different semiconductors may be provided with diversity via different epitaxial thicknesses, different dopings or intermixing, different numerical apertures (NAs), different working distances (WDs), or different polarizations. Different semiconductor devices may also be tuned to emit or receive different wavelengths of electromagnetic radiation. 
     The scatterometric sensors may receive much of the electromagnetic radiation that is emitted by an SMI sensor, returned from a target backscattering, but not received back into the resonant cavity of the SMI sensor. In some cases, and by way of example, the scatterometric sensors may capture up to 1000 ppm or more of the electromagnetic radiation emitted by an SMI sensor and subsequently returned from a target, whereas the SMI sensor that emitted the electromagnetic radiation may receive a return of less than 1 ppm of the emitted electromagnetic radiation. A mix of interferometric and scatterometric sensors can therefore be more power efficient as compared to one or an array of SMI sensors. 
     Optical subsystems of the optical sensor systems described herein may include overhead or on-chip optics (e.g., lenses, collimators, surface gratings (or coatings or treatments), beam splitters, waveguides, and so on) that steer emitted electromagnetic radiation to one or more focal points (e.g., as spot illumination) or one or more regions (e.g., as flood illumination) of a target. The overhead or on-chip optics may provide the same or different polarizations or other optical properties (e.g., NAs) for different semiconductor devices. The optical subsystems may also steer emitted electromagnetic radiation returned from the one or more focal points or regions to portions of an SMI sensor (e.g., to a resonant cavity of a semiconductor laser of an SMI sensor, and in some cases to an adjacent photodetector of an SMI sensor for SMI signal detection) and to a set of scatter photodetectors. 
     In some cases, the optical subsystem may steer and overlap part of the semiconductor laser&#39;s output power, with power returned from one or more focal points, to one or more adjacent photodetectors, thereby causing external coherent mixing on these photodetectors while other photodetectors serve as scatter photodetectors. 
     In some cases, multiple SMI sensors may be provided within a field of scatter photodetectors, and addressed such that a first of the SMI sensors and a plurality (or all) of the photodetectors are turned on while the remaining SMI sensors are turned off. The first SMI sensor may then be turned off and a second SMI sensor and a plurality of (or all) of the photodetectors may be turned on. 
     In some cases, multiple or all of a set of semiconductor devices formed on (or attached to) a substrate may be SMI sensors, and one of the SMI sensors may be biased to be operated as an SMI sensor while some or all of the other SMI sensors are biased to be operated as photodetectors. 
     In some cases, two or more SMI sensors may be operated at the same time and different subsets of photodetectors may detect the respective scatter of their electromagnetic radiation. This may be useful, for example, when a target is in close proximity to an optical sensor system and/or when a target is highly absorptive of the electromagnetic radiation emitted by the SMI sensors (e.g., when an optical sensor system is positioned against human tissue). Two or more SMI sensors may also be operated at the same time when they, and different subsets of photodetectors, are tuned to operate at different wavelengths. 
     The signals provided by an array of scatter photodetectors may in some cases be used to determine a power spectral density, or bidirectional reflectance distribution function (BRDF), or angular-resolved backscattering profile of a surface or target. The signals provided by scatter photodetectors can also provide information about the variation (or movement) of a target, at a particular angle, over time. 
     In some cases, a mix of interferometric and scatterometric sensors can provide better fidelity surface or sub-surface sensing, for characterizing things like exterior or interior surface roughness, blood flow within human tissue, a particle count or particle size, and so on. 
     These and other systems, devices, methods, and apparatus are described with reference to  FIGS.  1 - 19   . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
     Directional terminology, such as “top”, “bottom”, “upper”, “lower”, “front”, “back”, “over”, “under”, “above”, “below”, “left”, “right”, etc. is used with reference to the orientation of some of the components in some of the figures described below. Because components in various embodiments can be positioned in a number of different orientations, directional terminology is used for purposes of illustration only and is in no way limiting. The directional terminology is intended to be construed broadly, and therefore should not be interpreted to preclude components being oriented in different ways. Also, as used herein, the phrase “at least one of” preceding a series of items, with the term “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list. The phrase “at least one of” does not require selection of at least one of each item listed; rather, the phrase allows a meaning that includes at a minimum one of any of the items, and/or at a minimum one of any combination of the items, and/or at a minimum one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or one or more of each of A, B, and C. Similarly, it may be appreciated that an order of elements presented for a conjunctive or disjunctive list provided herein should not be construed as limiting the disclosure to only that order provided. 
       FIG.  1    shows an example plan view of an optical sensor system  100 . The optical sensor system  100  may be used for various purposes, and in some cases may be used to characterize an object, particles, a surface, a user, or other items within a field of view or optical focus of the optical sensor system  100 . 
     The optical sensor system  100  may include a set of semiconductor devices (e.g., an M×N array of semiconductor devices) formed on a semiconductor substrate  102  (e.g., a semiconductor wafer (or die), such as a silicon (Si) wafer, a gallium arsenide (GaAs) wafer, or an indium phosphide (InP) wafer). The semiconductor devices may include one or more SMI sensors  104  and a set (e.g., an array) of photodetectors  106 . Alternatively, the semiconductor devices may only include a set of SMI sensors  104 , with each SMI sensor  104  being selectively operable as an SMI sensor or a photodetector. Each SMI sensor  104  may include a semiconductor laser having a resonant cavity. The resonant cavity may be bounded by a pair of distributed Bragg reflectors (DBRs). Each SMI sensor  104  may also include 1) a photodetector configured to generate an SMI signal, such as a photodetector that is integrated with, stacked with, or adjacent to the semiconductor laser, or 2) a circuit that is configured to monitor a junction voltage or current of the semiconductor laser and generate an SMI signal. 
     An SMI sensor is defined herein as a sensor configured to generate electromagnetic radiation (e.g., light), emit the electromagnetic radiation from a resonant cavity (e.g., a resonant optical cavity, such as a multiple quantum well (MQW) resonant optical cavity), receive a returned portion of the electromagnetic radiation (e.g., electromagnetic radiation that reflects or scatters from a surface) back into the resonant cavity, coherently or partially coherently self-mix the generated and returned electromagnetic radiation within the resonant cavity, and produce an output indicative of the self-mixing (i.e., an SMI signal). The generated, emitted, and returned electromagnetic radiation may be coherent or partially coherent. In some examples, the electromagnetic radiation emitted by an SMI sensor may be generated by an electromagnetic radiation source such as a vertical-cavity surface-emitting laser (VCSEL), a vertical external-cavity surface-emitting laser (VECSEL), an edge-emitting laser (EEL), a horizontal cavity surface-emitting laser (HCSEL), a quantum-dot laser (QDL), a quantum cascade laser (QCL), or a light-emitting diode (LED) (e.g., an organic LED (OLED), a resonant-cavity LED (RC-LED), a micro LED (mLED), a superluminescent LED (SLED), or an edge-emitting LED), and so on. The generated, emitted, and returned electromagnetic radiation may include, for example, visible or invisible light (e.g., green light, red light, infrared (IR) light, ultraviolet (UV) light, and so on). The output of an SMI sensor (i.e., the SMI signal) may include a photocurrent produced by a photodetector (e.g., a photodiode), which photodetector is integrated with, or positioned under, above, or next to, the sensor&#39;s electromagnetic radiation source. Alternatively or additionally, the output of an SMI sensor may include a measurement of the current or junction voltage of the SMI sensor&#39;s electromagnetic radiation source. 
     By way of example,  FIG.  1    shows two SMI sensors  104  and thirty-eight photodetectors  106 , with each SMI sensor  104  being centered within a field of twenty-four photodetectors  106 . Practical implementations of the optical sensor system  100  may have one, a few, or many (e.g., dozens or hundreds) of SMI sensors  104 , and a few, several, or many (e.g., dozens, hundreds, or thousands) of photodetectors  106 . Each SMI sensor  104  may have a subset of photodetectors  106  that is distributed symmetrically about the SMI sensor  104 , or some or all of the SMI sensors  104  may have a subset (or all) of the photodetectors  106  distributed asymmetrically about the SMI sensor  104 . 
     In use, the SMI sensors  104  may be operated singularly and sequentially, but contemporaneously with a subset (or all) of the photodetectors  106 . For example, a first SMI sensor  104 - 1  may be operated to emit electromagnetic radiation from a resonant cavity of a semiconductor laser portion of the first SMI sensor  104 - 1 ; receive a retroflection of a portion of the emitted electromagnetic radiation (e.g., a portion of the emitted electromagnetic radiation that reflects off of an object, particles, a surface, a user, or other items within a field of view or optical focus of the SMI sensor  104 - 1 ) into the resonant cavity of the semiconductor laser; and coherently self-mix generated and retro-reflected electromagnetic radiation within the resonant cavity. In response to the self-mixing, the SMI sensor  104 - 1  may generate a first SMI modulation. Contemporaneously with the first SMI sensor  104 - 1  emitting electromagnetic radiation or receiving a retro-reflection of a portion of the emitted electromagnetic radiation, a first subset (or all) of the photodetectors  106  (e.g., the photodetectors  106  bounded by the imaginary box  108 - 1 ) may be operated to receive different target-backscattered portions of the electromagnetic radiation emitted by the SMI sensor  104 - 1 , and to generate a first set of angular-resolved scatter signals. In practical applications of the optical sensor system  100 , the SMI sensor  104 - 1  may receive less than 0.1%, and often much less than 1 ppm, of its emitted electromagnetic radiation as a retroflection, whereas the subset of photodetectors  106  may collectively receive greater than 1%, 5%, 10%, 20%, or more of the emitted electromagnetic radiation as scatter. The SMI sensor  104 - 1  may therefore be used to perform interferometric measurements using a small portion of the emitted electromagnetic radiation; and the subset of photodetectors  106  may be used to contemporaneously perform scatterometric measurements using a substantially greater portion of the emitted electromagnetic radiation. 
     After operating the first SMI sensor  104 - 1  and first subset of photodetectors  106 , a second SMI sensor  104 - 2  and second subset (or all) of the photodetectors  106  (e.g., the photodetectors  106  bounded by the imaginary box  108 - 2 ) may be operated contemporaneously, to generate a second SMI signal and second set of angular-resolved scatter signals. Alternatively, in embodiments in which each of the semiconductor devices on the semiconductor substrate  102  is an SMI sensor, one SMI sensor at a time may be operated as an SMI sensor, while a subset (or all) of the rest of the SMI sensors are operated as photodetectors instead of SMI sensors. 
     Examples of interferometric and scatterometric measurements include determinations of presence, distance, velocity, size, surface properties, particle count, and so on. 
       FIG.  2    shows an example elevation of an optical sensor system  200  including a wafer-integrated array of semiconductor devices. The optical sensor system  200  is an example of the optical sensor system described with reference to  FIG.  1   . 
     The optical sensor system  200  may include a set of semiconductor devices formed on a semiconductor substrate  202  (e.g., a semiconductor wafer (or die)). The semiconductor devices may include one or more SMI sensors  204  and a set (e.g., an array) of photodetectors  206 . Each SMI sensor  204  may include a semiconductor laser  208  having a resonant cavity  210 . The resonant cavity  210  may be bounded by a pair of distributed Bragg reflectors (DBRs)  212 ,  214 . By way of example, the SMI sensors  204  are shown to be VCSELs. Alternatively, the SMI sensors  204  may be HCSELs or other types of semiconductor lasers. Each SMI sensor  204  may also include a photodetector  216  configured to detect an SMI modulation, such as a photodetector  216  (e.g., an RPCD) that is adjacent to the semiconductor laser (or VCSEL)  208 . Alternatively, each SMI sensor  204  may include 1) a photodetector that is integrated or stacked with the semiconductor laser  208  and configured to generate an SMI signal, or 2) a circuit that is configured to monitor a junction voltage or current of the semiconductor laser  208  and generate an SMI signal. 
     The photodetectors  206  may be constructed similarly to the semiconductor lasers  208  and may be RCPDs. 
     The semiconductor lasers  208  and photodetectors  216  of the SMI sensors  204 , as well as the photodetectors  206 , may all share a subset of epitaxial layers  220  (or all of the epitaxial layers  218 ) formed on the semiconductor substrate  202 . For example, a set of epitaxial layers  218  may be deposited to form a set of lower DBR layers, a resonant cavity, and a set of upper DBR layers. Trenches  222  may then be etched or cut in the set of epitaxial layers  218  to define, and electrically decouple, an array of semiconductor devices (e.g., the semiconductor lasers  208 , photodetectors  216 , and photodetectors  206 ). In some cases, the trenches  222  may expose an aluminum (Al) rich layer in the epitaxial layers  218 , to be oxidized for optical and electrical aperture definition for the semiconductor laser  208 , the photodetector  216 , and so on. In some cases, a fill material (e.g., deep trench isolation (DTI), or ion implantation  224 ) may be deposited in at least portions of the trenches  222  to provide lateral electrical and/or optical separation (or isolation) between adjacent semiconductor devices. Also, the set of upper DBR layers may be etched to thin the upper DBR layers above the photodetectors  216 ,  206 , making the upper DBR layers over the photodetectors  216 ,  206  more transmissive to allow the photodetectors  216 ,  206  to receive a greater portion, larger field of view, and wider spectrum of the retroflected or scattered electromagnetic radiation emitted by the semiconductor lasers  208  (i.e., to improve collection efficiency of the photodetectors  216 ,  206 ). Regardless of whether some of the upper DBR layers are removed, a useful aspect of the optical sensor system  200  (and most all of the optical sensor systems described herein) is that electromagnetic emission and sensing is performed in-plane. For example, and as shown in  FIG.  2   , the resonant cavities  210  of the semiconductor lasers  208  and photodetectors (or RCPDs)  216 ,  206  may all be formed in-plane, using the same process. This can mitigate manufacturing variance (e.g., changes leading to variation in emitted or detected wavelengths), thermal variance, and so on. 
     In some embodiments, a common cathode  226  may be formed on the backside of the semiconductor substrate  202  (i.e., opposite a side of the semiconductor substrate  202  on which the set of epitaxial layers  218  is formed). A set of per-device anodes  228  may be formed on top of the upper DBR layers of each semiconductor device. Optionally, a per-device intra-cavity cathode  230  (e.g., a cathode  230  formed on the lower DBR of a semiconductor device and coupled to the device&#39;s resonant cavity) may be formed for some or all of the semiconductor devices. 
     An optical subsystem  234  may be disposed in an optical path of one, some, or all of the semiconductor devices. The optical subsystem  234  may in some cases include one or more global optic elements, each of which is positioned over the entire array of semiconductor devices formed on the semiconductor substrate  202 . Additionally or alternatively, the optical subsystem  234  may include one or more local optic elements, each of which is positioned over a singular semiconductor device or subset of semiconductor devices. 
     As shown, the optical subsystem  234  may in some cases include an optical beam splitter  236 , which splits a beam of electromagnetic radiation emitted by a semiconductor laser  208 , or which splits a retro-reflected portion of the electromagnetic radiation, to redirect the portion of the emitted or retro-reflected electromagnetic radiation toward the photodetector  216 . In alternative embodiments, in which the photodetector  216  is integrated or stacked with the semiconductor laser  208 , or in which a circuit is used to extract an SMI signal by monitoring the junction voltage or current of the semiconductor laser  208 , the optical beam splitter  236  need not be provided. 
     By way of example, the optical subsystem  234  is shown to be confocal. In other words, the optical subsystem  234  may direct electromagnetic radiation emitted by each of the semiconductor lasers  208  toward a focal point  232 , and may direct a retro-reflection and scatter from the focal point (within a range of incident angles) toward the semiconductor devices of the optical sensor system  200 , in an angular-resolved manner (i.e., the semiconductor lasers  208 , photodetectors  216 , and photodetectors  206  each receive electromagnetic radiation returned from the focal point at a particular incident angle, or particular range of incident angles, with respect to the focal point). 
     In some embodiments, the optical subsystem  234  may include a set of OCLs (i.e., lenses  238  formed directly on individual semiconductor devices, such as on individual ones of the semiconductor lasers  208  or photodetectors  216 ,  206 ). The OCLs may take the form of intrinsic OCLs (e.g., gallium arsenide (GaAs) lenses formed on an epitaxial stack) or extrinsic OCLs (e.g., lenses deposited after epitaxial processes have been completed, such as polymer or dielectric lenses). 
       FIGS.  3 - 5 B  show various alternative examples of the optical subsystem described with reference to  FIG.  2   . For example,  FIG.  3    shows an optical sensor system  300  including a telecentric-confocal imaging system  302  (an example of the optical subsystem described with reference to  FIG.  2   ) positioned apart from an array of semiconductor devices  304 . The array of semiconductor devices  304  may include a set of semiconductor lasers  306  and a set of photodetectors  308  (e.g., RCPDs). The semiconductor lasers  306  may be integrated or stacked with photodetectors, or associated with monitoring circuits or adjacent photodetectors  308 , to form SMI sensors  310 . By way of example, the optical sensor system  300  includes SMI sensors  310  in which photodetectors are stacked or integrated with respective semiconductor lasers  306 , or in which semiconductor lasers  306  are associated with respective monitoring circuits. Many aspects of the optical sensor system  300  may be similar to those of the optical sensor system described with reference to  FIG.  2   , and those aspects are numbered similarly. 
     The telecentric-confocal imaging system  302  may be positioned in a set of electromagnetic radiation emission paths of the set of semiconductor lasers  306 , and in a set of electromagnetic radiation reception paths of the set of photodetectors  308 . In some cases, the telecentric-confocal imaging system  302  may include a set of lenses  312 , such as a set of lenses including a telecentric F-theta scan lens with finite conjugates. 
       FIG.  4    shows an optical sensor system  400  including an OCL-confocal imaging system  402  (an example of the optical subsystem described with reference to  FIG.  2   ) and the array of semiconductor devices  304  described with reference to  FIG.  3   . The OCL-confocal imaging system  402  may include a set of OCLs  404  formed on the array of semiconductor devices  304  (e.g., on individual semiconductor lasers  306  and/or photodetectors  308 ). The OCL-confocal imaging system  402  may also include a confocal imaging system (e.g., one or more lenses, or a confocal imaging lens)  406  positioned apart from the array of semiconductor devices  304 , in both a set of electromagnetic radiation emission paths of the set of semiconductor lasers  306 , and in a set of electromagnetic radiation reception paths of the set of photodetectors  308 . Each OCL  404  may have a prescription (e.g., lens sag, lens shape, aperture offset, and so on) that is matched to the chief and marginal ray angles of the confocal imaging system  406 , and that corrects for aberration of the semiconductor device  304  on which it is disposed. In some embodiments, an on-chip wedge lens, diffractive grating, or meta surface may also be disposed on a semiconductor device  304 . 
       FIG.  5 A  shows an optical sensor system  500  including a beam-splitting and non-confocal imaging system  502  (an example of the optical subsystem described with reference to  FIG.  2   ) and an array of semiconductor devices  504 . The array of semiconductor devices  504  may include a set of semiconductor lasers  506  and a set of photodetectors  508  (e.g., RCPDs). The semiconductor lasers  506  may be integrated or stacked with photodetectors, or associated with monitoring circuits or adjacent photodetectors, to form SMI sensors  510 . By way of example, the optical sensor system  500  includes SMI sensors  510  in which SMI photodetectors  512  are disposed adjacent respective semiconductor lasers  506 . 
     The beam-splitting and non-confocal imaging system  502  may include an optical beam splitter, which in some cases may take the form of a reflective element  514  disposed on an imaging lens  516 , or a reflective element  518  disposed on a cover  520 , intermediate element, or other lens disposed in the optical path of a semiconductor laser  506 . In some cases, the reflective element  514  or  518  may include a reflective film, coating, surface treatment, or component. The reflective element  514  or  518  may redirect a portion of the electromagnetic radiation emitted by the semiconductor laser  506  toward an SMI photodetector  512 , and allow the remainder of the emitted beam to pass. In some cases, the reflective element  514  or  518  may be only partially reflective, allowing some electromagnetic radiation to pass through the reflective element  514  or  518 . In some cases, the reflective element  514  or  518  may completely reflect a wavelength of electromagnetic radiation emitted by the semiconductor laser  506 , but may be sized so that it only intersects part of an emitted beam of electromagnetic radiation, allowing some electromagnetic radiation to pass around the reflective element  514  or  518 . 
     The beam-splitting and non-confocal imaging system  502  may also include a non-confocal imaging system. The non-confocal imaging system may include, for example, 1) a non-confocal imaging lens  516 , with or without OCLs  522  on the semiconductor devices  504 , or 2) non-confocal OCLs  522  on the semiconductor devices  504 , with or without a confocal imaging lens  516 . 
     The non-confocal imaging system may enable one or more of the photodetectors  508  (e.g., different photodetectors or different subsets of photodetectors) to receive scatter from a different focal point  524  than a focal point  526  of the electromagnetic radiation emitted by the semiconductor laser  506 . This may in some cases enable the optical sensor system  500  to characterize a medium that exists between the focal point  526  of the emitted electromagnetic radiation and the focal point  524  of the photodetector  508 . In some cases, all of the photodetectors  508  used to detect scatter may receive scatter from the same focal point  524 . In some cases, different photodetectors  508  may be used to detect scatter from different focal points. In some cases, the beam-splitting and non-confocal imaging system  502  may also or alternatively provide different optical focuses for the electromagnetic radiation that is emitted from, and returned to, the resonant cavity of the semiconductor laser  506 . The different focal points of the different optical paths or different semiconductor devices  504  may be laterally offset in a plane parallel to a semiconductor substrate  528  on which the semiconductor devices  504  are formed, or may be located different distances along respective normal perpendicular to the semiconductor substrate  528 . 
       FIG.  5 B  shows an optical sensor system  530  including a beam combiner  532 . The beam combiner  532  may be used to facilitate external photon mixing (i.e., mixing of emitted and redirected electromagnetic radiation outside of a semiconductor laser&#39;s resonant cavity) instead of facilitating self-mixing interferometry (i.e., mixing of emitted and redirected electromagnetic radiation within a semiconductor laser&#39;s resonant cavity). An external photon-mixing sensor  534  of the optical sensor system  530  may include a semiconductor laser  536 , a first photodetector (e.g., a first photon-mixing detector  538 ) spaced apart from, adjacent, and/or in-plane with the semiconductor laser  536 , and possibly one or more additional photodetectors (e.g., a second photon-mixing detector  540 ) that are spaced apart from, adjacent, and/or in-plane with the semiconductor laser  536 . A portion of the electromagnetic radiation  542  emitted by the semiconductor laser  536  (e.g., 1% of the electromagnetic radiation) may be tapped into a lateral wave guiding mode in the beam combiner  532  via beam splitting structure  544 , while the majority of the electromagnetic radiation  542  (e.g., 99% of the electromagnetic radiation) may continue through one or more lenses  548  of a confocal imaging system  546 , toward focal point  550 . The beam splitting structure  544  may be or include a polarized beam splitter (PBS) cube, a surface relief grating (SRG), a volume Bragg grating (VBG), and so on. A portion of the emitted electromagnetic radiation that backscatters from a target located at the focal point  550  may be received by the one or more lenses  548  of the confocal imaging system  546  and directed toward the first photon-mixing detector  538  (for example, an RCPD as shown). At the same time, the portion of the emitted electromagnetic radiation (e.g., a local oscillator beam, LO) that is tapped into the lateral wave guiding mode in the beam combiner  532 , via the beam splitting structure  544 , may be tapped out of the beam combiner  532  by the beam combining structure  552 , to overlap and recombine with the electromagnetic radiation (e.g., a scene beam, SC) that is backscattered from the target. The beam combining structure  552  may be or include a PBS cube, an SRG, a VBG, and so on. The tapping out ratio may be, for example, about 20%, 50%, of 99%. Polarization optics may optionally be used to reduce loss of the SC beam through the beam combining structure  552 . The mode matching parts of the LO and SC beams may be mixed in the photon-mixing detector  538  and generate a heterodyne signal similar to an SMI signal, with the difference being that the external photon-mixing signal now carries target information from a backscattering angular cone different than the retroreflective cone of an SMI sensor. 
     In some cases, the LO beam may be further tapped out by the beam combining structure  554 , toward an additional photon-mixing detector  540 , and mixed with a different target-backscattered SC beam. The LO beam may be tapped out toward any number of photon-mixing detectors. 
     A number of photon-mixing detectors (e.g., photon-mixing detectors  538 ,  540 ) may be enabled by including various tapping out structures (e.g.,  552 ,  554 ) in the beam combiner  532 , creating a “coherent pixel”, with the rest of detector structures providing “incoherent pixels” (e.g., photodetectors  556 ). The incoherent pixels may provide traditional intensity-based scatterometry information (e.g., an intensity-based scatterometry signal), while coherent pixels may provide field-based coherent scatterometry information (e.g., a field-based coherent scatterometry signal) with higher SNR over path length and loss, as well as spatial sensing information such as target velocity, displacement, distance from a different perspective of SMI retroreflective angles, and so on. 
     Multiple or switchable tapping out structures (e.g.,  552 ,  554 ) can be enabled in the beam combiner  532 , to tap the LO beam out from different semiconductor lasers (e.g.,  536  and  558 )—at the same time or at selected different times. A tapping out structure (e.g.,  552  or  554 ) may also be switched off to switch the underlying detector (e.g.,  538  or  540 ) from a coherent pixel to an incoherent pixel. Such switchable tapping structures can be realized using liquid crystals, a microelectromechanical system (MEMS), or another adaptive optical technology. 
       FIGS.  6 A- 8    show alternative examples of cathode and anode routing for an array of semiconductor devices. In some cases, the semiconductor devices may include the semiconductor lasers and photodetectors described with reference to  FIGS.  1 - 5    or elsewhere in this description. 
       FIG.  6 A  shows an example elevation of an optical sensor system  600  having an array of semiconductor devices  602  formed on a semiconductor substrate  604 . The semiconductor devices  602  may include one or more SMI sensors  606  and a set of photodetectors  608  (e.g., RCPDs). A cathode  610  may be formed on a side of the semiconductor substrate  604  opposite a side of the semiconductor substrate  604  on which the array of semiconductor devices  602  is formed. The cathode  610  may be shared by (or common to) all of the semiconductor devices  602 . 
     A set of anode routings  612  may be formed on the array of semiconductor devices  602  (e.g., on electromagnetic radiation emitting/sensing surfaces of the semiconductor devices  602 ). The set of anode routings  612  may provide a means to address the semiconductor devices  602 . However, the density of the anode routings  612  may not allow for full addressability of the semiconductor devices  602 , and may only provide limited addressability in some cases. A representative plan view of some of the anode routings  612  is shown in  FIG.  6 B . 
       FIG.  7 A  shows an example elevation of another optical sensor system  700  having an array of semiconductor devices  702  formed on a semiconductor substrate  704 . The semiconductor devices  702  may include one or more SMI sensors  706  and a set of photodetectors  708  (e.g., RCPDs). A set of cathode routings  710  may be disposed in a set of trenches  712  that separate the semiconductor devices  702 , and a set of anode routings  714  may be disposed on the array of semiconductor devices  702  (e.g., on electromagnetic radiation emitting/sensing surfaces of the semiconductor devices  702 ). In this configuration, the set of cathode routings  710  and the set of anode routings  714  may each provide a means to address the semiconductor devices  702 . However, the density and layout of the cathode routings  710  and anode routings  714  may still not allow for full addressability of the semiconductor devices  702 , and may only provide limited addressability in some cases. 
     A representative plan view of some of the cathode and anode routings  710 ,  714  is shown in  FIG.  7 B . As shown, the set of cathode routings  710  may be oriented in a first set of parallel directions, and the set of anode routings  714  may be oriented in a second set of parallel directions, with the second set of parallel directions being orthogonal to the first set of parallel directions. In this plan, any single semiconductor device  702  (emitter or detector) may be individually addressed, one at a time; or a group of semiconductor devices  702 , each of which resides in a different row or column, may be contemporaneously addressed. A scanning sequence can be used to address any combination of semiconductors devices  702 , including emitters and/or detectors. 
       FIG.  8    shows an example elevation of another optical sensor system  800  having an array of semiconductor devices  802  formed on a semiconductor substrate  804 . The semiconductor devices  802  may include one or more SMI sensors  806  and a set of photodetectors  808  (e.g., RCPDs). 
     In  FIG.  8   , the semiconductor devices  802  are back-emitting and back-sensing. The semiconductor devices  802  may be flip-chip bonded to a second semiconductor substrate  810  (e.g., a Si substrate or other semiconductor wafer (or die)) that may include conductive traces  812  coupled to individual cathodes  814  or individual anodes  816  of the semiconductor devices  802 . In some embodiments, the semiconductor substrate  804  may be partially or fully removed (e.g., etched away). In a flip-chip configuration, every emitter/detector anode  816  and cathode  814  can be individually addressed simultaneously, through high density multi-layer interconnects in the second semiconductor substrate  810 . 
       FIGS.  9 A and  9 B  show example elevations of an optical sensor system  900  or  940  that includes an array of semiconductor devices  904  formed on a semiconductor substrate  902 . The array of semiconductor devices  904  may in some cases be formed from a shared set of epitaxial layers  906 . Each of the semiconductor devices  904  may include a resonant gain cavity  908 , and an integrated photodetector  910  (e.g., an intra-cavity photodetection layer grown between the semiconductor substrate  902  and the resonant gain cavity  908 ). A tunnel junction may be formed between the resonant gain cavity  908  and the integrated photodetector  910  of a semiconductor device  904 , to provide current insulation between the resonant gain cavity  908  and the integrated photodetector  910 . To minimize crosstalk and dark current flow between adjacent semiconductor devices  904 , lateral insulation may be provided between adjacent ones of the integrated photodetectors  910 . The lateral insulation may include, for example, an etched trench  912 , oxidation  920  (e.g., DTI) within the trench  912 , ion implantation (without a trench  912 ) and so on. 
     The optical sensor system  900  or  940  may or may not include an optical subsystem  918  (e.g., as described with reference to any of  FIGS.  2 - 5   ). 
       FIG.  9 A  shows an optical sensor system  900  in which one or more of the semiconductor devices  904  are SMI sensors  914 , such as VCSELs with integrated photodetectors  910 , and other semiconductor devices  904  are RCPDs  916  with additional integrated photodetectors  910 . Some of the epitaxial layers  906  may be etched away for the RCPDs  916 , such that the RCPDs  916  have a shallower and more transmissive upper DBR than the SMI sensors  914 . Additionally or alternatively, the apertures of the RCPDs  916  may be sized larger than those of the SMI sensors  914 , to improve scatter monitoring across a desired and/or greater range of incident angles, or within a desired and/or greater field of view. 
     In use, the VCSEL of an SMI sensor  914  may be provided with a forward current bias, and the integrated photodetector  910  of the SMI sensor  914  may be provided with a reverse voltage bias. In this mode of operation, the resonant gain cavity  908  of the VCSEL may emit electromagnetic radiation through an upper DBR of the SMI sensor  914 , and the integrated photodetector  910  can be used to generate an SMI signal (e.g., a photocurrent). For an RCPD  916 , both the resonant gain cavity  908  of the RCPD  916  and the integrated photodetector  910  stacked below the RCPD  916  may be reversely biased, and the photocurrent outputs of the RCPD  916  and integrated photodetector  910  may be ganged together or otherwise summed to generate a scatterometric signal. This can increase the responsivity of a semiconductor device  904  that is used for scatter detection. Alternatively, only the RCPD  916  or the integrated photodetector  910  may be used to generate a scatterometric signal. 
       FIG.  9 B  shows an optical sensor system  940  in which all of the semiconductor devices  904  are SMI sensors  942 , such as VCSELs with integrated photodetectors  910 . In the optical sensor system  940 , none of the epitaxial layers  906  need be etched away. 
     In use, the VCSEL of one of the SMI sensors  942  may be provided with a forward current bias, and its integrated photodetector  910  may be provided with a reverse voltage bias. In this mode of operation, the resonant gain cavity  908  of the VCSEL may emit electromagnetic radiation through an upper DBR of the SMI sensor  942 , and the integrated photodetector  910  can be used to generate an SMI signal (e.g., a photocurrent). All other SMI sensors  942  may contemporaneously be operated as RCPDs with integrated photodetectors  910 , with both the resonant gain cavity  908  and the integrated photodetector  910  of each of the other SMI sensors  942  being reversely biased, and with the photocurrent outputs of the resonant gain cavity  908  and integrated photodetector  910  being ganged together or otherwise summed to generate a scatterometric signal. Similarly to the optical sensor system  900 , this can increase the responsivity of a semiconductor device  904  that is used for scatter detection. Alternatively, only the resonant gain cavity  908  or the integrated photodetector  910  of an RCPD-configured SMI sensor may be used to generate a scatterometric signal. 
     After one of the SMI sensors  942  is operated as such, a different one of the SMI sensors  942  may be operated as such while the remaining SMI sensors  942  are contemporaneously operated as RCPDs with integrated photodetectors  910 . 
       FIG.  9 C  shows an optical sensor system  980  similar to the optical sensor system described with reference to  FIG.  9 A , but instead of each of the semiconductor devices  904  having an integrated photodetector (or intra-cavity photodetection layer) grown between the semiconductor substrate  902  and the resonant gain cavity  908  of a semiconductor device  904 , a photodetector (e.g., an indium gallium arsenide (InGaAs) photodetector)  982  is grown above a resonant gain cavity  908  of an SMI sensor  984 . In some cases, InGaP layers may be formed over all of the semiconductor devices  904 , and selectively removed from those that are ultimately configured as RCPDs  986 . In other cases, InGaAs layers may only be formed on semiconductor devices  904  that are ultimately configured as SMI sensors  984 . 
     In any of the optical sensor systems  900 ,  940 ,  980  described with reference to  FIGS.  9 A- 9 C , a photodetection multiplication layer may be grown between the resonant gain cavity  908  and integrated photodetector  910 . With a heavy reverse bias, linear avalanche amplification can be achieved. In other words, a resonant cavity avalanche photodetector (RC-APD) may be formed. An RC-APD may provide a higher signal level (e.g., a signal strength that is 5-100× that of an RCPD) and a higher signal-to-noise ratio (SNR). In some cases, an RC-APD may be further reverse biased into Geiger mode, making the RC-APD capable of single photon counting. 
       FIG.  10    shows an optical sensor system  1000  in which some of its semiconductor devices are formed on a substrate  1002  (e.g., a semiconductor substrate), using a common process, and one or more other semiconductor devices are picked, placed, and soldered onto the substrate  1002 . For example, an array of photodetectors  1004  may be formed directly on the substrate  1002 , which in some cases may be a Si substrate. A semiconductor laser  1006  (e.g., a VCSEL) may then be bonded (e.g., flip-chip bonded) to the substrate  1002 . In some cases, the semiconductor laser  1006  may be integrated with a photodetector. In other cases, the semiconductor laser  1006  may be mounted over a photodetector  1004  that has already been formed on the substrate  1002 . Fabricating photodetectors  1004  on a separate substrate  1002  (e.g., a Si substrate) with respect to the semiconductor laser&#39;s epi (e.g., GaAs) allows for a higher density photodetector arrangement, higher speed readout, more wafer-level signal processing capability, and lower manufacturing cost. It is possible to form universal or individually customized dielectric thin film filters and on-chip micro-optics on the photodetectors  1004  to enhance their angular and spectral selectivity with respect to the semiconductor laser  1006  and optical sensor system  1000 . 
     The optical sensor system  1000  may or may not include an optical subsystem  1008  (e.g., as described with reference to any of  FIGS.  2 - 5   ). In some cases, the optical subsystem  1008  may include an OCL  1010  formed on the back side of the semiconductor laser  1006 . 
     In an alternative arrangement of what is shown in  FIG.  10   , all of the semiconductor devices  1004 ,  1006  may be soldered to the substrate  1002 —either in a pre-formed array of semiconductor devices, or as individual semiconductor devices. 
       FIG.  11    shows a method  1100  of operating a set of semiconductor devices to contemporaneously obtain interferometric and scatterometric measurements. The method  1100  may in some cases be performed by a processor, in communication with one of the optical sensor systems described herein. 
     At block  1102 , the method  1100  may include operating a first semiconductor device in the set of semiconductor devices to emit electromagnetic radiation from a resonant cavity of the first semiconductor device. 
     At block  1104 , the method  1100  may include determining a set of parameters of an SMI signal generated as a result of self-mixing of electromagnetic radiation within the resonant cavity. 
     At block  1106 , and contemporaneously with operating the first semiconductor device and determining the set of parameters of the SMI signal, the method  1100  may include sensing a scatter of the emitted electromagnetic radiation using a subset of semiconductor devices in the set of semiconductor devices. 
     At block  1108 , the method  1100  may include characterizing at least one of an environment of an electronic device that includes the set of semiconductor devices, or a relationship between the electronic device and the environment, using the determined set of parameters of the SMI signal and the sensed scatter. Characterizing the environment may in some cases include characterizing an object, particles, a surface, a user, or other items within the environment. 
     In some embodiments, the operations at blocks  1102 - 1106  may be repeated, with different semiconductor devices (e.g., SMI sensors) emitting electromagnetic radiation and generating SMI signals sequentially, while other semiconductor devices (e.g., photodetectors) contemporaneously generate scatter signals in response to the electromagnetic radiation emitted by an SMI sensor. The operations at block  1108  may then include characterizing at least one of an environment of an electronic device that includes the set of semiconductor devices, or a relationship between the electronic device and the environment, using all of the determined sets of parameters of the SMI signals and the sensed scatter corresponding to all of the SMI signals. 
     In some embodiments, the accuracy or resolution of the characterization made at block  1108  may be improved by adding diversity to the SMI sensors and/or photodetectors. For example, different ones of the SMI sensors and/or photodetectors may emit or receive electromagnetic radiation at different angles of incident with respect to an object or surface in an environment, or have different numerical apertures (NAs), different working distances (WDs), or different polarizations. Different SMI sensors may also emit different electromagnetic radiation wavelengths. 
     The method  1100  may be performed to characterize a variety of relationships between an electronic device and its environment, as described, for example, with reference to  FIGS.  12 - 14 B . 
       FIG.  12    shows an example use of an optical sensor system  1200  to characterize a quality of a surface  1202 . The optical sensor system  1200  may be any of the optical sensor systems described herein, and by way of example is shown to be the optical sensor system described with reference to  FIG.  2   . In some embodiments, a processor  1204  of the optical sensor system  1200  may characterize the quality of the surface  1202  by performing the method described with reference to  FIG.  11    (i.e., characterizing the environment of an electronic device may include characterizing the quality of the surface  1202 ). 
     As shown, the optical sensor system  1200  may include at least one SMI sensor  1206  and an array of scatter-detecting photodetectors  1208 . Alternatively, the optical sensor system  1200  may include an array of SMI sensors  1206 , some of which may be operated as SMI sensors  1206  while others are operated as scatter-detecting photodetectors  1208 . An optical subsystem  1210  (e.g., as described with reference to any of  FIGS.  2 - 5   ) may or may not be provided on or over some or all of the SMI sensors  1206  or photodetectors  1208 . 
     The processor  1204  may receive one or more SMI signals generated by one or more of the SMI sensors  1206  and determine a set of parameters for the SMI signal(s). The processor  1204  may then use the set of parameters to characterize a speckle, roughness, or texture of the surface  1202 . 
     Contemporaneously with receiving the one or more SMI signals, the processor  1204  may use the photodetectors  1208  to sense a scatter of electromagnetic radiation emitted by the one or more SMI sensors  1206  (e.g., the processor  1204  may receive one or more scatter signals generated by the photodetectors  1208 ). The processor  1204  may use the sensed scatter to determine a power spectral density (or BRDF, or angular-resolved backscattering profile) of the surface. The power spectral density may provide one or more parallel scatter channels (i.e., channels parallel to one or more SMI channels) for determining a roughness or texture of, or correlation length for, the surface  1202 . The processor  1204  may then perform a sensor fusion process to fuse the surface characterizations obtained from the SMI and scatter channels. In some cases, this may provide a richer characterization of the surface  1202 , with minimal additional power overhead than using the SMI or scatter channel alone. For example, SMI-based sensing, alone, requires some sort of movement between the optical sensor system  1200  and the surface  1202 , and may require multiple SMI channels to accurately characterize a surface (e.g., to accurately characterize surface qualities such as roughness or texture). In some cases, the SMI channel(s) may provide a velocity and some roughness information for the surface  1202 , and the scatter channels may provide more detailed roughness information for one or more spots on the surface  1202 . 
     Although  FIG.  12    shows the SMI sensors  1206  and photodetectors  1208  having a singular optical focus, some or all of the SMI sensors  1206  and/or photodetectors  1208  may alternatively have different optical focuses, or the emission and return paths for electromagnetic radiation emitted and received into a resonant cavity of an SMI sensor  1206  may have different optical focuses. Providing a known lateral offset  1300  (see, e.g.,  FIG.  13 A ), horizontal offset, and/or combined lateral and horizontal offset  1302  (see, e.g.,  FIG.  13 B ) in the optical focuses of the sensors  1206  and photodetectors  1208  can enable the processor  1204  to better characterize a sub-surface of a non-metal, aqueous, transparent, or otherwise optically-permeable object, such as human tissue, paper, polymers, coatings, and so on. The improved characterization is due to the spatial information (e.g., depth information or other offset information) that the different optical focuses provide. 
     By way of example, the optical sensor systems shown in  FIGS.  13 A and  13 B  are useful in a wearable device (or other type of device) that is used to characterize layers of tissue, blood flow (e.g., heartbeat or heartrate), biometric features, or other characteristics (e.g., muscle or bone movements) of a user that are based on tissues or structures located below the exterior surface of a body part of a user. 
     Besides collecting non-confocal incoherent backscattering information, a multiple optical focus configuration may be applied to an external photon-mixing architecture as shown in  FIG.  5 B . An optical beam combiner may enable mixing of an LO beam with SC beams from one or multiple backscatter paths. Non-confocal and angular-resolved coherent backscattering information could be collected, and combined with incoherent angular-resolved information to better characterize tissue dynamics. Similarly, such an external photon-mixing architecture may be used in the optical sensor systems and applications described with reference to  FIGS.  14  and  15   . 
       FIG.  14    shows an example use of an optical sensor system  1400  to characterize particles  1402  or air quality within an environment. The optical sensor system  1400  may be any of the optical sensor systems described herein, and by way of example is shown to be the optical sensor system described with reference to  FIG.  2   . In some embodiments, a processor  1404  of the optical sensor system  1400  may characterize the particles  1402  or an air quality by performing the method described with reference to  FIG.  11    (i.e., characterizing the environment of an electronic device may include characterizing the particles  1402  or an air quality). 
     As shown, the optical sensor system  1400  may include at least one SMI sensor  1406  and an array of scatter-detecting photodetectors  1408 . Alternatively, the optical sensor system  1400  may include an array of SMI sensors  1406 , some of which may be operated as SMI sensors  1406  while others are operated as scatter-detecting photodetectors  1408 . An optical subsystem  1410  (e.g., as described with reference to any of  FIGS.  2 - 5 B ) may or may not be provided on or over some or all of the SMI sensors  1406  or photodetectors  1408 . 
     The processor  1404  may receive one or more SMI signals generated by one or more of the SMI sensors  1406  and determine a set of parameters for the SMI signal(s). The processor  1404  may then use the set of parameters to characterize the particles  1402  (e.g., a speed, size, surface quality, or density of the particles  1402 ). 
     Contemporaneously with receiving the one or more SMI signals, the processor  1404  may use the photodetectors  1408  to sense a scatter of electromagnetic radiation emitted by the one or more SMI sensors  1406  (e.g., the processor  1404  may receive one or more scatter signals generated by the photodetectors  1408 ). The processor  1404  may use the sensed scatter to determine a power spectral density (or BRDF, or angular-resolved backscattering profile) of the environment, and analyze the power spectral density to determine a size (particle size) of the particles  1402 . 
     The processor  1404  may use the parameter(s) of the SMI signal(s) and/or the sensed scatter to determine a particulate matter concentration or air quality. The processor  1404  may in some cases use the sensed scatter to identify low counts of particles  1402  and/or properties of slow-moving particles  1402 , and use the SMI signals to characterize high counts of particles  1402  and/or fast-moving particles  1402 . The processor  1404  may in some cases use the sensed scatter to identify false positives or false negatives in particle characterizations made using the SMI signal(s) (or vice versa, using the SMI signal(s) to identify false positives or false negatives in particle characterizations made using the sensed scatter). 
     In some embodiments, the processor  1404  may selectively power down the SMI sensors  1406 , or operate the SMI sensors  1406  in a low power state, for a period of time after determining there are relatively few particles  1402  or the particles  1402  are relatively slow-moving. 
       FIGS.  15 A and  15 B  show example uses of an optical sensor system  1500  to characterize a relationship between an electronic device that carries the optical sensor system  1500  and a surface  1502 . The optical sensor system  1500  may be any of the optical sensor systems described herein, and by way of example is shown to be the optical sensor system described with reference to  FIG.  2   . In some embodiments, a processor  1504  of the optical sensor system  1500  may characterize the relationship between the electronic device and the surface  1502  by performing the method described with reference to  FIG.  11   . 
     As shown, the optical sensor system  1500  may include at least one SMI sensor  1506  and an array of scatter-detecting photodetectors  1508 . Alternatively, the optical sensor system  1500  may include an array of SMI sensors  1506 , some of which may be operated as SMI sensors  1506  while others are operated as scatter-detecting photodetectors  1508 . 
     An optical subsystem  1510  (e.g., as described with reference to any of  FIGS.  2 - 5   ) may be provided on or over some or all of the SMI sensors  1506  or photodetectors  1508 . As shown in  FIG.  15 A , the optical subsystem  1510  may fan out the electromagnetic radiation emitted by an SMI sensor  1506  to illuminate a broad swath  1512  of the surface  1502  (i.e., the optical subsystem  1510  may flood a region of the surface with illumination). Alternatively, and as shown in  FIG.  15 B , the optical subsystem  1510  may include an optical beam splitter that splits the electromagnetic radiation emitted by an SMI sensor  1506  to illuminate different points on the surface  1502 . As another option, and as part of the optical subsystem  1510  described with reference to  FIG.  15 A or  15 B  or any of the optical subsystems described with reference to  FIGS.  2 - 5   , the optical subsystem  1510  may actively scan a beam of electromagnetic radiation emitted by an SMI sensor over the surface  1502 . The scanning may result in a single point, multiple points, a line or lines or other structured pattern of illumination, or flood illumination may be scanned over the surface  1502 . 
     The processor  1504  may receive one or more SMI signals generated by one or more of the SMI sensors  1506  and determine a set of parameters for the SMI signal(s). Contemporaneously with receiving the one or more SMI signals, the processor  1504  may use the photodetectors  1508  to sense a scatter of electromagnetic radiation emitted by the one or more SMI sensors  1506  (e.g., the processor  1504  may receive one or more scatter signals generated by the photodetectors  1508 ). 
     The processor  1504  may use the parameter(s) of the SMI signal(s) and/or the sensed scatter to track movement of the optical sensor system  1500  over the surface  1502  (or movement of the surface  1502  with respect to the optical sensor system  1500 ). The processor  1504  may in some cases use the SMI signal(s) to track movement of the optical sensor system  1500  with respect to the surface  1502 , and may rely on the SMI signal(s) solely or to a greater degree during high-speed movement of the optical sensor system  1500  (e.g., movement less than a threshold speed of movement). The processor may in some cases use the scatter signals to track movement of the optical sensor system  1500  with respect to the surface  1502 , and may rely on the scatter signals solely or to a greater degree during low-speed movement of the optical sensor system  1500  (e.g., movement above the threshold speed of movement). The scatter signals may be used to track optical flow of the emitted electromagnetic radiation (e.g., a movement of structured light and/or changes in a spatial speckle pattern on the surface  1502 ). 
     Movement between the optical sensor system  1500  and surface  1502  may also be tracked using both the SMI signal(s) and scatter signals. Sensitivity, fidelity, and power consumption can be optimized between SMI and scatter channels for tracking a particular type of surface  1502  (e.g., digital input, biometric acquisition, bio-authentication, and so on). In some cases, SMI signals may be used for high-speed tracking or make/break determinations, and scatter signals (or optical flow analysis) can be used for fine or low-speed tracking, or calibration of SMI thermal, speckle, or spatial crosstalk. 
       FIGS.  16 A and  16 B  show an example of a device  1600  (an electronic device) that includes an optical sensor system  1624 , such as any of the optical sensor systems described herein. The optical sensor system  1624  may be used, for example, to acquire biological information from the wearer or user of the device  1600  (e.g., a heart rate, respiration rate, blood pressure, blood flow rate, blood oxygenation, blood glucose level, and so on), or to determine a status of the device  1600  (e.g., whether the device  1600  is being worn or a tightness of the device  1600 ), or parameters of an environment of the device  1600  (e.g., an air quality or particle concentration). The device&#39;s dimensions and form factor, and inclusion of a band  1604  (e.g., a wrist band), suggest that the device  1600  is an electronic watch, fitness monitor, or health diagnostic device. However, the device  1600  could alternatively be any type of wearable device.  FIG.  16 A  shows a front isometric view of the device  1600 , and  FIG.  16 B  shows a back isometric view of the device  1600 . 
     The device  1600  may include a body  1602  (e.g., a watch body) and a band  1604 . The body  1602  may include an input or selection device, such as a crown  1618  or a button  1620 . The band  1604  may be attached to a housing  1606  of the body  1602 , and may be used to attach the body  1602  to a body part (e.g., an arm, wrist, leg, ankle, or waist) of a user. The body  1602  may include a housing  1606  that at least partially surrounds a display  1608 . In some embodiments, the housing  1606  may include a sidewall  1610 , which sidewall  1610  may support a front cover  1612  ( FIG.  16 A ) and/or a back cover  1614  ( FIG.  16 B ). The front cover  1612  may be positioned over the display  1608 , and may provide a window through which the display  1608  may be viewed. In some embodiments, the display  1608  may be attached to (or abut) the sidewall  1610  and/or the front cover  1612 . In alternative embodiments of the device  1600 , the display  1608  may not be included and/or the housing  1606  may have an alternative configuration. 
     The display  1608  may include one or more light-emitting elements including, for example, light-emitting elements that define a light-emitting diode (LED) display, organic LED (OLED) display, liquid crystal display (LCD), electroluminescent (EL) display, or other type of display. In some embodiments, the display  1608  may include, or be associated with, one or more touch and/or force sensors that are configured to detect a touch and/or a force applied to a surface of the front cover  1612 . 
     In some embodiments, the sidewall  1610  of the housing  1606  may be formed using one or more metals (e.g., aluminum or stainless steel), polymers (e.g., plastics), ceramics, or composites (e.g., carbon fiber). The front cover  1612  may be formed, for example, using one or more of glass, a crystal (e.g., sapphire), or a transparent polymer (e.g., plastic) that enables a user to view the display  1608  through the front cover  1612 . In some cases, a portion of the front cover  1612  (e.g., a perimeter portion of the front cover  1612 ) may be coated with an opaque ink to obscure components included within the housing  1606 . In some cases, all of the exterior components of the housing  1606  may be formed from a transparent material, and components within the device  1600  may or may not be obscured by an opaque ink or opaque structure within the housing  1606 . 
     The back cover  1614  may be formed using the same material(s) that are used to form the sidewall  1610  or the front cover  1612 . In some cases, the back cover  1614  may be part of a monolithic element that also forms the sidewall  1610 . In other cases, and as shown, the back cover  1614  may be a multi-part back cover, such as a back cover having a first back cover portion  1614 - 1  attached to the sidewall  1610  and a second back cover portion  1614 - 2  attached to the first back cover portion  1614 - 1 . The second back cover portion  1614 - 2  may in some cases have a circular perimeter and an arcuate exterior surface  1616  (i.e., an exterior surface  1616  having an arcuate profile). 
     The front cover  1612 , back cover  1614 , or first back cover portion  1614 - 1  may be mounted to the sidewall  1610  using fasteners, adhesives, seals, gaskets, or other components. The second back cover portion  1614 - 2 , when present, may be mounted to the first back cover portion  1614 - 1  using fasteners, adhesives, seals, gaskets, or other components. 
     A display stack or device stack (hereafter referred to as a “stack”) including the display  1608  may be attached (or abutted) to an interior surface of the front cover  1612  and extend into an interior volume of the device  1600 . In some cases, the stack may include a touch sensor (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other type of touch sensing elements), or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or part of a touch sensor system) may be configured to detect a touch applied to an outer surface of the front cover  1612  (e.g., to a display surface of the device  1600 ). 
     In some cases, a force sensor (or part of a force sensor system) may be positioned within the interior volume below and/or to the side of the display  1608  (and in some cases within the device stack). The force sensor (or force sensor system) may be triggered in response to the touch sensor detecting one or more touches on the front cover  1612  (or a location or locations of one or more touches on the front cover  1612 ), and may determine an amount of force associated with each touch, or an amount of force associated with the collection of touches as a whole. The force sensor (or force sensor system) may alternatively trigger operation of the touch sensor (or touch sensor system), or may be used independently of the touch sensor (or touch sensor system). 
     The device  1600  may include various sensors. In some embodiments, the device  1600  may have a port  1622  (or set of ports) on a side of the housing  1606  (or elsewhere), and an ambient pressure sensor, ambient temperature sensor, internal/external differential pressure sensor, gas sensor, particulate matter concentration sensor, or air quality sensor may be positioned in or near the port(s)  1622 . In some cases, the sensor may include the optical sensor system  1624 . In other embodiments, the optical sensor system  1624  may perform its sensing through the front cover  1612  (and in some cases through the display  1608 ), through the back cover  1614 , through the button  1620 , through the top or ring of the crown  1618 , or through the sidewall of the housing  1606 . 
     In some cases, one or more skin-facing sensors  1626  may be included within the device  1600 . The skin-facing sensor(s)  1626  may emit or transmit signals through the housing  1606  (or back cover  1614 ) and/or receive signals or sense conditions through the housing  1606  (or back cover  1614 ). For example, in some embodiments, one or more such sensors may include a number of electromagnetic radiation emitters (e.g., visible light and/or IR emitters) and/or a number of electromagnetic radiation detectors (e.g., visible light and/or IR detectors, such as any of the electromagnetic radiation detectors described herein). The sensors may be used, for example, to acquire biological information from the wearer or user of the device  1600  (e.g., a heart rate, respiration rate, blood pressure, blood flow rate, blood oxygenation, blood glucose level, and so on), or to determine a status of the device  1600  (e.g., whether the device  1600  is being worn or a tightness of the device  1600 ). In some cases, the skin-facing sensor(s)  1626  may include the optical sensor system  1624 . 
     The device  1600  may include circuitry (e.g., a processor and/or other components) configured to determine or extract, at least partly in response to signals received directly or indirectly from one or more of the device&#39;s sensors, and by way of example, biological parameters of the device&#39;s user, a status of the device  1600 , and/or parameters or characteristics of an environment of the device  1600 . In some embodiments, the circuitry may be configured to convey the determined or extracted parameters or statuses via an output device of the device  1600 . For example, the circuitry may cause the indication(s) to be displayed on the display  1608 , indicated via audio or haptic outputs, transmitted via a wireless communications interface or other communications interface, and so on. The circuitry may also or alternatively maintain or alter one or more settings, functions, or aspects of the device  1600 , including, in some cases, what is displayed on the display  1608 . 
       FIGS.  17 A and  17 B  show another example of a device  1700  (an electronic device) that includes an optical sensor system  1728 . The optical sensor system  1728  may be used, for example, to acquire biological information from the user of the device  1700 , to determine parameters of an environment of the device  1700  (e.g., air quality), or to determine a distance to, movement of, or composition of a target or object. 
     The device&#39;s dimensions and form factor, including the ratio of the length of its long sides to the length of its short sides, suggest that the device  1700  is a mobile phone (e.g., a smartphone). However, the device&#39;s dimensions and form factor are arbitrarily chosen, and the device  1700  could alternatively be any portable electronic device including, for example, a mobile phone, tablet computer, portable computer, portable music player, portable terminal, vehicle navigation system, robot navigation system, or other portable or mobile device. The device  1700  could also be a device that is semi-permanently located (or installed) at a single location (e.g., a door lock, thermostat, refrigerator, or other appliance).  FIG.  17 A  shows a front isometric view of the device  1700 , and  FIG.  17 B  shows a rear isometric view of the device  1700 . The device  1700  may include a housing  1702  that at least partially surrounds a display  1704 . The housing  1702  may include or support a front cover  1706  or a rear cover  1708 . The front cover  1706  may be positioned over the display  1704 , and may provide a window through which the display  1704  (including images displayed thereon) may be viewed by a user. In some embodiments, the display  1704  may be attached to (or abut) the housing  1702  and/or the front cover  1706 . 
     The display  1704  may include one or more light-emitting elements or pixels, and in some cases may be an LED display, an OLED display, an LCD, an EL display, a laser projector, or another type of electronic display. In some embodiments, the display  1704  may include, or be associated with, one or more touch and/or force sensors that are configured to detect a touch and/or a force applied to a surface of the front cover  1706 . 
     The various components of the housing  1702  may be formed from the same or different materials. For example, a sidewall  1718  of the housing  1702  may be formed using one or more metals (e.g., stainless steel), polymers (e.g., plastics), ceramics, or composites (e.g., carbon fiber). In some cases, the sidewall  1718  may be a multi-segment sidewall including a set of antennas. The antennas may form structural components of the sidewall  1718 . The antennas may be structurally coupled (to one another or to other components) and electrically isolated (from each other or from other components) by one or more non-conductive segments of the sidewall  1718 . The front cover  1706  may be formed, for example, using one or more of glass, a crystal (e.g., sapphire), or a transparent polymer (e.g., plastic) that enables a user to view the display  1704  through the front cover  1706 . In some cases, a portion of the front cover  1706  (e.g., a perimeter portion of the front cover  1706 ) may be coated with an opaque ink to obscure components included within the housing  1702 . The rear cover  1708  may be formed using the same material(s) that are used to form the sidewall  1718  or the front cover  1706 , or may be formed using a different material or materials. In some cases, the rear cover  1708  may be part of a monolithic element that also forms the sidewall  1718  (or in cases where the sidewall  1718  is a multi-segment sidewall, those portions of the sidewall  1718  that are non-conductive). In still other embodiments, all of the exterior components of the housing  1702  may be formed from a transparent material, and components within the device  1700  may or may not be obscured by an opaque ink or opaque structure within the housing  1702 . 
     The front cover  1706  may be mounted to the sidewall  1718  to cover an opening defined by the sidewall  1718  (i.e., an opening into an interior volume in which various electronic components of the device  1700 , including the display  1704 , may be positioned). The front cover  1706  may be mounted to the sidewall  1718  using fasteners, adhesives, seals, gaskets, or other components. 
     A display stack or device stack (hereafter referred to as a “stack”) including the display  1704  (and in some cases the front cover  1706 ) may be attached (or abutted) to an interior surface of the front cover  1706  and extend into the interior volume of the device  1700 . In some cases, the stack may also include a touch sensor (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other type of touch sensing elements), or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or part of a touch sensor system) may be configured to detect a touch applied to an outer surface of the front cover  1706  (e.g., to a display surface of the device  1700 ). 
     The stack may also include one or an array of sensors  1716 , with the sensors positioned in front of or behind, or interspersed with, the light-emitting elements of the display  1704 . In some cases, an array of sensors  1716  may extend across an area equal in size to the area of the display  1704 . Alternatively, the array of sensors  1716  may extend across an area that is smaller than or greater than the area of the display  1704 , or may be positioned entirely adjacent the display  1704 . Although the array of sensors  1716  is shown to have a rectangular boundary, the array could alternatively have a boundary with a different shape, including, for example, an irregular shape. The array of sensors  1716  may be variously configured as an ambient light sensor, a health sensor (e.g., age sensor), a touch sensor, a proximity sensor, a health sensor, a biometric sensor (e.g., a fingerprint sensor or facial recognition sensor), a camera, a depth sensor, an air quality sensor, and so on. The array of sensors  1716  may also or alternatively function as a proximity sensor, for determining whether an object (e.g., a finger, face, or stylus) is proximate to the front cover  1706 . In some embodiments, the array of sensors  1716  may provide the touch sensing capability (i.e., touch sensor) of the stack. In some embodiments, the array of sensors  1716  may include or be the optical sensor system  1728 . 
     In some cases, a force sensor (or part of a force sensor system) may be positioned within the interior volume below and/or to the side of the display  1704  (and in some cases within the stack). The force sensor (or force sensor system) may be triggered in response to the touch sensor detecting one or more touches on the front cover  1706  (or indicating a location or locations of one or more touches on the front cover  1706 ), and may determine an amount of force associated with each touch, or an amount of force associated with the collection of touches as a whole. 
     As shown primarily in  FIG.  17 A , the device  1700  may include various other components. For example, the front of the device  1700  may include one or more front-facing cameras  1710  (including one or more image sensors), speakers  1712 , microphones, or other components  1714  (e.g., audio, imaging, and/or sensing components) that are configured to transmit or receive signals to/from the device  1700 . In some cases, a front-facing camera  1710 , alone or in combination with other sensors, may be configured to operate as a bio-authentication or facial recognition sensor. Additionally or alternatively, the array of sensors  1716  may be configured to operate as a front-facing camera  1710 , a bio-authentication sensor, or a facial recognition sensor. In some cases, one or more of the sensors may include one of the optical sensor systems described herein. 
     The device  1700  may also include buttons or other input devices positioned along the sidewall  1718  and/or on a rear surface of the device  1700 . For example, a volume button or multipurpose button  1720  may be positioned along the sidewall  1718 , and in some cases may extend through an aperture in the sidewall  1718 . The sidewall  1718  may include one or more ports  1722  that allow air, but not liquids, to flow into and out of the device  1700 . In some embodiments, one or more sensors may be positioned in or near the port(s)  1722 . For example, an ambient pressure sensor, ambient temperature sensor, internal/external differential pressure sensor, gas sensor, particulate matter concentration sensor, or air quality sensor may be positioned in or near a port  1722 . 
     In some embodiments, the rear surface of the device  1700  may include a rear-facing camera  1724 . A flash or light source  1726  may also be positioned along the rear of the device  1700  (e.g., near the rear-facing camera). In some cases, the rear surface of the device  1700  may include multiple rear-facing cameras. 
     In some cases, the sensor(s)  1716 , the front-facing camera  1710 , the rear-facing camera  1724 , and/or other sensors positioned on the front, back, or sides of the device  1700  may emit or transmit signals through the housing  1702  (including the front cover  1706 , rear cover  1708 , or sidewall  1718 ) and/or receive signals or sense conditions through the housing  1702 . For example, in some embodiments, one or more such sensors may include a number of electromagnetic radiation emitters (e.g., visible light and/or IR emitters) and/or a number of electromagnetic radiation detectors (e.g., visible light and/or IR detectors, such as any of the electromagnetic radiation detectors described herein). 
     The device  1700  may include circuitry (e.g., a processor and/or other components) configured to determine or extract, at least partly in response to signals received directly or indirectly from one or more of the device&#39;s sensors, biological parameters of the device&#39;s user, a status of the device  1700 , parameters of an environment of the device  1700  (e.g., air quality), or a composition of a target or object, for example. In some embodiments, the circuitry may be configured to convey the determined or extracted parameters or statuses via an output device of the device  1700 . For example, the circuitry may cause the indication(s) to be displayed on the display  1704 , indicated via audio or haptic outputs, transmitted via a wireless communications interface or other communications interface, and so on. The circuitry may also or alternatively maintain or alter one or more settings, functions, or aspects of the device  1700 , including, in some cases, what is displayed on the display  1704 . 
     In embodiments, the optical sensor system  1728  may perform its sensing through the front cover  1706  (e.g., though openings in, around, or adjacent components  1714 ,  1710 , or  1712 , and in some cases through the display  1704 ); through openings in, around, or adjacent components  1724  or  1726 ; through the button  1720 ; through openings in, around, or adjacent ports  1622 ; and so on. 
       FIG.  18    shows an example of a mouse  1800  (an electronic device) that includes an optical sensor system  1804 . The mouse  1800  may include a shell or housing  1802 . The optical sensor system  1804  may be mounted within the housing  1802 , and may emit electromagnetic radiation toward a surface  1806  over which the mouse  1800  is moved. A processor  1808  that receives interferometric and scatterometric signals from the optical sensor system  1804  may use the signals to track the mouse&#39;s location with respect to the surface  1806 . In some cases, the processor  1808  may perform the method described with reference to  FIG.  11    or use the processing techniques described with reference to  FIG.  15   . 
       FIG.  19    shows a sample electrical block diagram of an electronic device  1900 , which electronic device may in some cases be the electronic device described with reference to  FIG.  16 A- 16 B,  17 A- 17 B , or  18 . The electronic device  1900  may optionally include an electronic display  1902  (e.g., a light-emitting display), a processor  1904 , a power source  1906 , a memory  1908  or storage device, a sensor system  1910 , and/or an input/output (I/O) mechanism  1912  (e.g., an input/output device, input/output port, or haptic input/output interface). The processor  1904  may control some or all of the operations of the electronic device  1900 . The processor  1904  may communicate, either directly or indirectly, with some or all of the other components of the electronic device  1900 . For example, a system bus or other communication mechanism  1914  can provide communication between the electronic display  1902 , the processor  1904 , the power source  1906 , the memory  1908 , the sensor system  1910 , and the I/O mechanism  1912 . 
     The processor  1904  may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions, whether such data or instructions is in the form of software or firmware or otherwise encoded. For example, the processor  1904  may include a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a controller, or a combination of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. In some cases, the processor  1904  may provide part or all of the processing system or processor described herein. 
     It should be noted that the components of the electronic device  1900  can be controlled by multiple processors. For example, select components of the electronic device  1900  (e.g., the sensor system  1910 ) may be controlled by a first processor and other components of the electronic device  1900  (e.g., the electronic display  1902 ) may be controlled by a second processor, where the first and second processors may or may not be in communication with each other. 
     The power source  1906  can be implemented with any device capable of providing energy to the electronic device  1900 . For example, the power source  1906  may include one or more batteries or rechargeable batteries. Additionally or alternatively, the power source  1906  may include a power connector or power cord that connects the electronic device  1900  to another power source, such as a wall outlet. 
     The memory  1908  may store electronic data that can be used by the electronic device  1900 . For example, the memory  1908  may store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, instructions, and/or data structures or databases. The memory  1908  may include any type of memory. By way of example only, the memory  1908  may include random access memory, read-only memory, Flash memory, removable memory, other types of storage elements, or combinations of such memory types. 
     The electronic device  1900  may also include one or more sensor systems  1910  positioned almost anywhere on the electronic device  1900 . In some cases, the sensor systems  1910  may include one or more of the optical sensor systems described herein. The sensor system(s)  1910  may be configured to sense one or more types of parameters, such as but not limited to, vibration; light; touch; force; heat; movement; relative motion; biometric data (e.g., biological parameters) of a user; air quality; proximity; position; connectedness; surface quality; and so on. By way of example, the sensor system(s)  1910  may include an SMI sensor, a heat sensor, a position sensor, a light or optical sensor, an accelerometer, a pressure transducer, a gyroscope, a magnetometer, a health monitoring sensor, and an air quality sensor, and so on. Additionally, the one or more sensor systems  1910  may utilize any suitable sensing technology, including, but not limited to, interferometric, magnetic, capacitive, ultrasonic, resistive, optical, acoustic, piezoelectric, or thermal technologies. 
     The I/O mechanism  1912  may transmit or receive data from a user or another electronic device. The I/O mechanism  1912  may include the electronic display  1902 , a touch sensing input surface, a crown, one or more buttons (e.g., a graphical user interface “home” button), one or more cameras (including an under-display camera), one or more microphones or speakers, one or more ports such as a microphone port, and/or a keyboard. Additionally or alternatively, the I/O mechanism  1912  may transmit electronic signals via a communications interface, such as a wireless, wired, and/or optical communications interface. Examples of wireless and wired communications interfaces include, but are not limited to, cellular and Wi-Fi communications interfaces. 
     The foregoing description, for purposes of explanation, uses specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art, after reading this description, that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art, after reading this description, that many modifications and variations are possible in view of the above teachings. 
     As described above, one aspect of the present technology may be the gathering and use of data available from various sources, including biometric data (e.g., the surface quality of a user&#39;s skin or fingerprint). The present disclosure contemplates that, in some instances, this gathered data may include personal information data that uniquely identifies or can be used to identify, locate, or contact a specific person. Such personal information data can include, for example, biometric data (e.g., fingerprint data) and data linked thereto (e.g., demographic data, location-based data, telephone numbers, email addresses, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information). 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to authenticate a user to access their device, or gather performance metrics for the user&#39;s interaction with an augmented or virtual world. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user&#39;s general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of advertisement delivery services, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide data to targeted content delivery services. In yet another example, users can select to limit the length of time data is maintained or entirely prohibit the development of a baseline profile for the user. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data at a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be selected and delivered to users by inferring preferences based on non-personal information data or a bare minimum amount of personal information, such as the content being requested by the device associated with a user, other non-personal information available to the content delivery services, or publicly available information.

Metadata:
Filing Date: 20210331
Publication Date: 20230103
Grant Date: 20230103
Priority Date: 20210331
Inventors: CHEN, TONG
TAN, FEI
JIN, Mingzhou
Assignee: APPLE INC
CPC Classifications: [{"code": "G01D5/266", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01D5/26", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01D5/34", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01B9/02004", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01P5/26", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01B9/02092", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01N21/47", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01B9/0207", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01P3/68", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/42", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01J2001/448", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01B9/02092", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J3/447", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J3/4412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J2001/446", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01B9/02092", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01B11/303", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01J2001/444", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01B9/02029", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01B9/02092", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01N21/47", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 83404975