Patent Publication Number: US-2023136184-A1

Title: Photosensor and band-pass filter included in photosensor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority benefit of Japanese Patent Application No. JP 2021-177718 filed in the Japan Patent Office on Oct. 29, 2021. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a photosensor and a band-pass filter included in a photosensor. 
     It is known that a vertical cavity surface emitting laser (VCSEL) is used for a light source of a photosensor. 
     An example of the related art is disclosed in Japanese Patent Laid-open No. 2012-185107. 
     SUMMARY 
     However, in the VCSEL, the wavelength of emitted light shifts when the environmental temperature changes. Thus, when light with a predetermined wavelength is received, a band-pass filter made in consideration of temperature variation is necessary. Therefore, there is a possibility that a noise component becomes large due to widening of the pass band of the band-pass filter. 
     It is desirable that the present disclosure provides a photosensor and a band-pass filter that can suppress a noise component of received light. 
     According to one example of the present disclosure, provided is a photosensor that measures a state of a detection subject, the photosensor including a light source that emits irradiation light in a wavelength band including a specific peak wavelength to the detection subject, a band-pass filter that allows the irradiation light reflected by the detection subject to be selectively transmitted through the band-pass filter, a light receiver that receives the irradiation light transmitted through the band-pass filter, and a measuring device that measures the state of the detection subject by using the light received by the light receiver. The light source has a temperature characteristic in which the specific wavelength peak of the emitted irradiation light shifts by a first wavelength shift amount depending on an environmental temperature. The band-pass filter has a temperature characteristic in which the specific wavelength peak of the emitted irradiation light shifts by a second wavelength shift amount depending on the environmental temperature. In the photosensor, a shape and a material of the band-pass filter are selected in such a manner that the second wavelength shift amount is equivalent to the first wavelength shift amount. 
     Furthermore, according to another example of the present disclosure, provided is a band-pass filter included in the photosensor according to claim  1 , the band-pass filter including a base, a first layer in which a first refractive index layer is stacked on the base and a first stack layer is stacked on the first refractive index layer in a thickness direction, a plurality of second layers in which a first cavity layer having a second refractive index higher than a first refractive index is stacked over the first layer, in which the first refractive index layer is stacked on the first cavity layer, and in which a second stack layer is stacked on the first refractive index layer, a third layer in which a second cavity layer having the second refractive index is stacked on an uppermost layer in the plurality of second layers, in which the first refractive index layer is stacked on the second cavity layer, and in which a third stack layer is stacked on the first refractive index layer, and a cap layer stacked on the third layer. Shapes and materials of the first layer, the second layers, and the third layer are selected in such a manner that the second wavelength shift amount is equivalent to the first wavelength shift amount. 
     According to the present disclosure, a photosensor that can suppress a noise component of received light can be provided. Furthermore, a band-pass filter used for the photosensor can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a configuration diagram illustrating a photosensor according to a first embodiment; 
         FIG.  2    is a configuration diagram illustrating a band-pass filter according to the present embodiment; 
         FIG.  3    is a configuration diagram illustrating a detailed structure of a semiconductor multilayer film according to the present embodiment; 
         FIG.  4    is a characteristic diagram illustrating a relation between a pass band and block bands of a semiconductor band-pass filter according to the present embodiment; 
         FIG.  5    is a characteristic diagram illustrating a relation between temperature and transmittance with respect to irradiation light of the semiconductor band-pass filter according to the present embodiment; 
         FIG.  6    is a characteristic diagram illustrating a relation between an angle of incidence and the transmittance with respect to the irradiation light of the semiconductor band-pass filter according to the present embodiment; 
         FIG.  7    is a configuration diagram illustrating a band-pass filter according to a second embodiment; 
         FIG.  8    is a configuration diagram illustrating a band-pass filter according to a modification example of the second embodiment; 
         FIG.  9    is a configuration diagram illustrating a band-pass filter and a light receiver according to a third embodiment; and 
         FIG.  10    is a configuration diagram illustrating a band-pass filter and a light receiver according to a modification example of the third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Next, embodiments will be described with reference to the drawings. In description of the drawings to be explained below, the same or similar part is given the same or similar reference sign. However, it should be noted that the drawings are schematic ones and a relation between a thickness and planar dimensions of each constituent part, and other numerical relations are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following explanation. Further, it is obvious that a part different in the mutual dimensional relationship or ratio is included also between the drawings. 
     Moreover, the embodiments provided below are what exemplify devices and methods for embodying technical ideas and are not what specify the material, shape, structure, arrangement, and other elements of each constituent part. Various changes can be added to the embodiments in the scope of claims. 
     A photosensor according to the present disclosure will be described. 
     First Embodiment 
     (Configuration of Photosensor) 
       FIG.  1    is one example of a configuration diagram of a photosensor according to a first embodiment. 
     As illustrated in  FIG.  1   , a photosensor  1  according to the present embodiment includes a light source  11 , a light projecting lens  12 , a light receiving lens  13 , a band-pass filter  14 , a light receiver  15 , and a measuring device  16 . 
     For example, the photosensor  1  irradiates a detection subject  21  with light and receives reflected light. Specifically, in the photosensor  1 , the light source  11  emits light to irradiate the detection subject  21  with the light through the light projecting lens  12  as illustrated in  FIG.  1   . Further, in the photosensor  1 , the light receiver  15  receives the light reflected by the detection subject  21  through the light receiving lens  13  and the band-pass filter  14 . Moreover, the photosensor  1  measures the distance between the photosensor  1  and the detection subject  21  by the measuring device  16  with use of the received light. The photosensor  1  may use a triangulation system to analyze the light reception position of the light receiver  15  and measure the distance, for example. In addition, the photosensor  1  may use a time-of-flight system to measure the time until light is received through being reflected by the detection subject  21  and measure the distance by calculation processing, for example. Alternatively, the presence or absence of the detection subject  21  around the photosensor  1  may be determined based on the light reception intensity of the light receiver  15 . In the following description, the distance between the photosensor  1  and the detection subject  21 , the presence or absence of the detection subject  21  around the photosensor  1 , or other states, each serving as information indicating the state of the relation between the photosensor  1  and the detection subject  21 , will be referred to also as “the state of the detection subject  21 .” 
     The light source  11  emits light with a wavelength of  800  to 1000 nm, for example. Specifically, the light source  11  may include a vertical cavity surface emitting laser (VCSEL) that emits light with a wavelength of  920  to 970 nm, for example. The light source  11  may include a distributed feedback (DFB) laser or a photonic crystal laser. In the following description, the light source  11  will be explained as a vertical cavity surface emitting laser. 
     The light source  11  has a temperature characteristic in which a specific wavelength peak of emitted light shifts by a first wavelength shift amount, depending on the environmental temperature. The first wavelength shift amount of the light source  11  is 0.07 nm/°C, for example. Further, the light source  11  emits irradiation light in a wavelength band including the specific peak wavelength to a detection subject, for example. The environmental temperature refers to the ambient temperature of the light source  11  here. 
     The light projecting lens  12  focuses the light emitted from the light source  11  to execute irradiation. The light projecting lens  12  may convert the light emitted by the light source  11  to substantially collimated light flux. 
     The light receiving lens  13  receives the irradiation light reflected by the detection subject  21  and focuses the light. The light receiving lens  13  may convert the irradiation light reflected by the detection subject  21  to substantially collimated light flux. 
     The band-pass filter  14  allows the irradiation light reflected by the detection subject  21  to be selectively transmitted through the band-pass filter  14 . That is, the band-pass filter  14  cuts off ambient light in a wavelength band that does not include the specific peak wavelength. The ambient light is light incident on the light receiver  15  from the external environment and is present in a wide wavelength band. The band-pass filter  14  may be disposed between the detection subject  21  and the light receiving lens  13 , instead of being disposed between the light receiving lens  13  and the light receiver  15 . That is, the irradiation light reflected by the detection subject  21  may be transmitted through the band-pass filter  14  first, and the irradiation light may be focused by the light receiving lens  13 . Details of the configuration of the band-pass filter  14  will be described later. 
     The light receiver  15  receives the irradiation light reflected by the detection subject  21 . The light receiver  15  may include a photodiode, for example. 
     The measuring device  16  measures the state of the detection subject  21  by using the light received by the light receiver  15 . Specifically, the measuring device  16  measures the distance between the photosensor  1  and the detection subject  21  by using the light received by the light receiver  15 . The measuring device  16  may analyze the position of the received light by using the light received by the light receiver  15 . Further, the measuring device  16  may measure the time from emission of light by the light source  11  to reception of the light by the light receiver  15  through reflection by the detection subject  21  and measure the distance by calculation processing. Alternatively, the presence or absence of the detection subject  21  around the photosensor  1  may be determined based on the light reception intensity of the light receiver  15 . 
     (Configuration of Band-Pass Filter) 
     Next, the configuration of a band-pass filter  14 A according to the present embodiment will be described. 
       FIG.  2    is one example of a configuration diagram illustrating the band-pass filter  14 A according to the present embodiment.  FIG.  3    is one example of a configuration diagram illustrating the detailed structure of a semiconductor multilayer film  142 A according to the present embodiment. 
     As illustrated in  FIG.  2   , the band-pass filter  14 A according to the present embodiment includes a semiconductor band-pass filter  241  and a dielectric band-pass filter  242 . In  FIG.  2   , the semiconductor band-pass filter  241  is disposed on the side of the light receiver  15 , and the dielectric band-pass filter  242  is disposed on the side of the detection subject  21 . The semiconductor band-pass filter  241  may be disposed on the side of the detection subject  21 , and the dielectric band-pass filter  242  may be disposed on the side of the light receiver  15 . 
     The semiconductor band-pass filter  241  and the dielectric band-pass filter  242  allow irradiation light reflected by the detection subject  21  to be selectively transmitted through them. That is, as illustrated in  FIG.  2   , the irradiation light reflected by the detection subject  21  is transmitted through the semiconductor band-pass filter  241  after being transmitted through the dielectric band-pass filter  242 . Further, the semiconductor band-pass filter  241  and the dielectric band-pass filter  242  cut off ambient light. The reason that the band-pass filter  14 A includes the dielectric band-pass filter  242  is that ambient light is cut off in a wavelength band of a wider range than the range when the semiconductor band-pass filter  241  is used alone. 
     The semiconductor band-pass filter  241  has a temperature characteristic in which a specific wavelength peak shifts by a second wavelength shift amount, depending on the environmental temperature. The environmental temperature refers to the ambient temperature of the semiconductor band-pass filter here. The shift amount of the wavelength that shifts depending on the temperature regarding the semiconductor band-pass filter  241  is referred to as the second wavelength shift amount. The second wavelength shift amount is adjusted through setting of a configuration shape and materials of the semiconductor band-pass filter  241 . In the semiconductor band-pass filter  241 , the configuration shape and the materials of the semiconductor band-pass filter  241  are selected in such a manner that the second wavelength shift amount that occurs depending on the environmental temperature is equivalent to the first wavelength shift amount that occurs depending on the environmental temperature of the light source  11 . Specifically, when the first wavelength shift amount that occurs depending on the environmental temperature of the light source  11  is 0.07 nm/°C, it suffices that the photosensor  1  uses the band-pass filter  14  including the semiconductor band-pass filter  241  in which the second wavelength shift amount is 0.07 nm/°C on the basis of the configuration shape and the materials of the semiconductor band-pass filter  241 . 
     As illustrated in  FIG.  2   , the semiconductor band-pass filter  241  includes a semiconductor substrate  141 A that is one example of the base and a semiconductor multilayer film  142 A that is one example of a first semiconductor multilayer film and in which plural semiconductor layers having semiconductor materials are stacked. Specifically, the semiconductor band-pass filter  241  has a structure in which the semiconductor multilayer film  142 A in which the plural semiconductor layers having the semiconductor materials are stacked is formed on the semiconductor substrate  141 A. An anti-reflection film (anti-reflection coating: AR coating) may be formed on the surfaces of the face oriented toward the side of the light receiver  15  in the semiconductor substrate  141 A and the face oriented toward the side of the detection subject  21  in the semiconductor multilayer film  142 A. 
     It suffices that the semiconductor substrate  141 A is at least either one substrate of a single-element semiconductor substrate or a compound semiconductor substrate, for example. As the material of the single-element semiconductor substrate, for example, silicon (Si), germanium (Ge), or other compounds may be used. Further, as the material of the compound semiconductor substrate, for example, gallium arsenide (GaAs), gallium phosphide (GaP), gallium nitride (GaN), indium phosphide (InP), silicon carbide (SiC), zinc oxide (ZnO), cadmium telluride (CdTe), zinc selenide (ZnSe), or other compounds may be used. 
     As illustrated in  FIG.  3   , the semiconductor multilayer film  142 A includes a first layer Y 1 , plural second layers Y 2 , a third layer Y 3 , and a cap layer  202 LT, for example. For the semiconductor multilayer film  142 A, the second wavelength shift amount that occurs depending on the environmental temperature is set based on the film thickness that is one example of the shape and the refractive index that is one example of the property of the material regarding the individual semiconductor layers stacked in the first layer Y 1 , the second layers Y 2 , the third layer Y 3 , and the cap layer  202 LT. 
     For example, the first layer Y 1  includes a first refractive index layer  201 LB that is one example of a first semiconductor layer stacked on the semiconductor substrate  141 A that is one example of the base and a first stack layer S 1  stacked on the first refractive index layer  201 LB. In the following description, one example of the first semiconductor layer will be referred to also as the first refractive index layer  201 LB. 
     The first stack layer S 1  includes plural first layered structures (PB1, PB2, ···, PBm). Specifically, the first layered structure is a structure in which a first refractive index layer  201 B that is one example of a third semiconductor layer is stacked on a second refractive index layer  202 B that is one example of a second semiconductor layer and has a higher refractive index than the first refractive index layer and the second refractive index layer  202 B and the first refractive index layer  201 B pair up. In the following description, the structure in which the second refractive index layer  202 B and the first refractive index layer  201 B pair up will be referred to as the first layered structure. 
     The first refractive index layer  201 LB and the first refractive index layer  201 B have a lower refractive index than the second refractive index layer  202 B. Specifically, for example, aluminum gallium arsenide (Al 0.85 GaAs) having a refractive index n = 3.073 may be used for the first refractive index layer  201 LB and the first refractive index layer  201 B. Further, for example, gallium arsenide (GaAs) having a refractive index n = 3.589 may be used for the second refractive index layer  202 B. Although the aluminum gallium arsenide having a refractive index n = 3.073 and the gallium arsenide having a refractive index n = 3.589 are cited as one example, the materials are not limited thereto. 
     It suffices that the film thicknesses of the first refractive index layer  201 LB, the second refractive index layer  202 B, and the first refractive index layer  201 B are approximately 40 to 100 nm, for example. 
     For example, the second layer Y 2  includes a first cavity layer  203 LM that is one example of a fourth semiconductor layer stacked on the first layer Y 1  and has a higher refractive index than the first refractive index layer, a first refractive index layer  201 LM that is one example of a fifth semiconductor layer stacked on the first cavity layer  203 LM, and a second stack layer S 2  stacked on the first refractive index layer  201 LM. In the following description, the fourth semiconductor layer having a higher refractive index than the first refractive index layer will be referred to also as the first cavity layer  203 LM. 
     The second stack layer S 2  includes plural first layered structures (PM1, PM2, ···, PMm). Specifically, the first layered structure (PM1, PM2, ···, PMm) is a structure in which a first refractive index layer  201 M that is one example of a seventh semiconductor layer is stacked on a second refractive index layer  202 M that is one example of a sixth semiconductor layer such that the second refractive index layer  202 M and the first refractive index layer  201 M pair up. In the following description, the structure in which the second refractive index layer  202 M and the first refractive index layer  201 M pair up will be referred to also as the first layered structure. 
     The first cavity layer  203 LM and the second refractive index layer  202 M have a higher refractive index than the first refractive index layer  201 LM and the first refractive index layer  201 M. Specifically, for example, gallium arsenide (GaAs) having a refractive index n = 3.589 may be used for the first cavity layer  203 LM and the second refractive index layer  202 M. For the first refractive index layer  201 LM and the first refractive index layer  201 M, for example, aluminum gallium arsenide (Al 0.85 GaAs) having a refractive index n = 3.073 may be used. Although the aluminum gallium arsenide having a refractive index n = 3.073 and the gallium arsenide having a refractive index n = 3.589 are cited as one example, the materials are not limited thereto. 
     It suffices that the film thicknesses of the first refractive index layer  201 LM, the second refractive index layer  202 M, and the first refractive index layer  201 M are approximately 40 to 100 nm, for example. Further, it suffices that the film thickness of the first cavity layer  203 LM is approximately  100  to 700 nm, for example. 
     For example, the third layer Y 3  includes a second cavity layer  203 LT that is one example of an eighth semiconductor layer stacked on the second layer Y 2  and has a higher refractive index than the first refractive index layer, a first refractive index layer  201 LT that is one example of a ninth semiconductor layer stacked on the second cavity layer  203 LT, and a third stack layer S 3  stacked on the first refractive index layer  201 LT. In the following description, the eighth semiconductor layer having a higher refractive index than the first refractive index layer will be referred to also as the second cavity layer  203 LT. 
     The third stack layer S 3  includes plural first layered structures (PT1, PT2, ···, PTm). Specifically, the first layered structure (PT1, PT2, ···, PTm) is a structure in which a first refractive index layer  201 T that is one example of an eleventh semiconductor layer is stacked on a second refractive index layer  202 T that is one example of a tenth semiconductor layer such that the second refractive index layer  202 T and the first refractive index layer  201 T pair up. In the following description, the structure in which the second refractive index layer  202 T and the first refractive index layer  201 T pair up will be referred to as the first layered structure. 
     The second cavity layer  203 LT and the second refractive index layer  202 T have a higher refractive index than the first refractive index layer  201 LT and the first refractive index layer  201 T. Specifically, for example, gallium arsenide (GaAs) having a refractive index n = 3.589 may be used for the second cavity layer  203 LT and the second refractive index layer  202 T. For the first refractive index layer  201 LT and the first refractive index layer  201 T, for example, aluminum gallium arsenide (Al 0.85 GaAs) having a refractive index n = 3.073 may be used. Although the aluminum gallium arsenide having a refractive index n = 3.073 and the gallium arsenide having a refractive index n = 3.589 are cited as one example, the materials are not limited thereto. 
     It suffices that the film thicknesses of the first refractive index layer  201 LT, the second refractive index layer  202 T, and the first refractive index layer  201 T are approximately 40 to 100 nm, for example. Further, it suffices that the film thickness of the second cavity layer  203 LT is approximately  100  to 700 nm, for example. 
     The cap layer  202 LT is a semiconductor layer that is stacked on the third layer and has a higher refractive index than the first refractive index layer. For the cap layer  202 LT, for example, gallium arsenide (GaAs) having a refractive index n = 3.589 may be used. Although the gallium arsenide (GaAs) having a refractive index n = 3.589 is cited as one example, the material is not limited thereto. Further, it suffices that the film thickness of the cap layer  202 LT is approximately  100  to 700 nm, for example. 
     As illustrated in  FIG.  2   , the dielectric band-pass filter  242  includes a dielectric substrate  143 A and a dielectric multilayer film  144 A in which plural dielectric layers having dielectric materials are stacked. Specifically, the dielectric band-pass filter  242  has a structure in which the dielectric multilayer film  144 A in which the plural dielectric layers having the dielectric materials are stacked is formed on the dielectric substrate  143 A. An anti-reflection film (AR coating) may be formed on the surfaces of the face oriented toward the side of the light receiver  15  in the dielectric substrate  143 A and the face oriented toward the side of the detection subject  21  in the dielectric multilayer film  144 A. The internal configuration of the dielectric band-pass filter  242  is publicly known, and therefore, description of the internal configuration is omitted. 
       FIG.  4    is a characteristic diagram illustrating a relation between a pass band and block bands of the semiconductor band-pass filter  241  according to the present embodiment.  FIG.  5    is a characteristic diagram illustrating a relation between temperature and transmittance with respect to irradiation light of the semiconductor band-pass filter  241  according to the present embodiment.  FIG.  6    is a characteristic diagram illustrating a relation between an angle of incidence and the transmittance with respect to the irradiation light of the semiconductor band-pass filter  241  according to the present embodiment. 
     In  FIG.  4   , the relation between the pass band and the block bands of the semiconductor band-pass filter  241  indicates that irradiation light reflected by the detection subject  21  is transmitted through the pass band of a wavelength band of approximately  935  to 955 nm and is cut off by the block bands of wavelength bands of 935 nm or less and 955 nm or more. That is, as illustrated in  FIG.  4   , the semiconductor band-pass filter  241  allows the transmission of the irradiation light by the wavelength band including a specific peak wavelength (here, wavelength 945 nm) and cuts off ambient light in the block bands. Ambient light in wavelength bands of 890 nm or less and 1010 nm or more is cut off by the dielectric band-pass filter  242 . 
     In  FIG.  5   , the relation between the temperature and the transmittance with respect to the irradiation light of the semiconductor band-pass filter  241  indicates that the peak wavelength of the irradiation light reflected by the detection subject  21  shifts depending on the environmental temperature. Specifically, regarding the irradiation light, for example, the peak wavelength is 945 nm when the environmental temperature is 30° C., whereas the peak wavelength shifts to 957 nm when the environmental temperature is 80° C. That is, the semiconductor band-pass filter  241  has the second wavelength shift amount of 0.077 nm/°C by which the specific wavelength peak of the light that can be transmitted shifts depending on the environmental temperature. 
     In  FIG.  6   , the relation between the angle of incidence and the transmittance with respect to the irradiation light of the semiconductor band-pass filter  241  indicates that the peak wavelength of the irradiation light reflected by the detection subject  21  shifts depending on the angle of incidence with respect to the irradiation light. 
     Specifically, regarding the irradiation light, for example, the peak wavelength is 945 nm when the angle of incidence is 0°, whereas the peak wavelength shifts to 920 nm when the angle of incidence is 60°. That is, in the semiconductor band-pass filter  241 , the specific wavelength peak of the light that can be transmitted shifts depending on light incident from an oblique direction as the irradiation light. The shift amount depending on the angle of incidence regarding the semiconductor band-pass filter  241  is 15 nm/° when the angle of incidence is 40°, for example. This shift amount is smaller than a shift amount of 89.4 nm/° when the angle of incidence is 40° regarding the dielectric band-pass filter, for example. The light incident from an oblique direction here is light whose angle of incidence is 1° to 90°. 
     As above, in the photosensor  1  of the first embodiment, for the light source  11  having a temperature characteristic in which the specific wavelength peak of emitted irradiation light shifts by the first wavelength shift amount depending on the environmental temperature, the band-pass filter  14  having a temperature characteristic in which the specific wavelength peak shifts by the second wavelength shift amount depending on the environmental temperature is disposed. Further, the configuration shape and materials of the band-pass filter  14  are selected in such a manner that the second wavelength shift amount is equivalent to the first wavelength shift amount. Therefore, according to the photosensor  1  of the first embodiment, when the first wavelength shift amount by which the specific wavelength peak of emitted irradiation light shifts occurs depending on the environmental temperature, the band of transmission can be set narrow due to the configuration in which the band-pass filter  14  having the semiconductor band-pass filter  241  has the temperature characteristic in which the specific wavelength peak shifts by the second wavelength shift amount equivalent to the first wavelength shift amount. Thus, the noise component of the received light can be suppressed. 
     Moreover, in the photosensor  1  of the first embodiment, the shift amount depending on the angle of incidence of the received light is small relative to that in the dielectric band-pass filter due to the inclusion of the band-pass filter  14  having the semiconductor band-pass filter  241 . Therefore, the band of transmission becomes less liable to change, and the noise component of the received light can be suppressed. 
     In the photosensor  1  of the first embodiment, due to the suppression of the noise component of the received light, the accuracy of the measurement value of the distance between the photosensor  1  and the detection subject  21  becomes high. Thus, the photosensor  1  of the first embodiment can accurately measure the distance between the photosensor  1  and the detection subject  21 . Moreover, due to the suppression of the noise component of the received light, sensing of the detection subject is enabled even under a condition that the intensity of the irradiation light is weak. 
     Second Embodiment 
     (Configuration of Band-Pass Filter) 
     A band-pass filter  14 B according to a second embodiment will be described. 
       FIG.  7    is one example of a configuration diagram illustrating the band-pass filter  14 B according to the second embodiment. 
     The band-pass filter  14 B according to the second embodiment has a different configuration with respect to the band-pass filter  14 A of  FIG.  2   . Specifically, the band-pass filter  14 A according to the first embodiment includes the semiconductor band-pass filter  241  and the dielectric band-pass filter  242 , whereas the band-pass filter  14 B according to the second embodiment includes a semiconductor band-pass filter  243  as illustrated in  FIG.  7   . The configuration of the photosensor  1  other than the band-pass filter  14 B according to the second embodiment is the same as the photosensor  1  of the first embodiment. 
     Specifically, the semiconductor band-pass filter  243  includes a semiconductor substrate  141 B that is one example of the base, a semiconductor multilayer film  142 B that is one example of the first semiconductor multilayer film and in which plural semiconductor layers having semiconductor materials are stacked, and a dielectric multilayer film  144 B in which plural dielectric layers having dielectric materials are stacked. 
     That is, the semiconductor band-pass filter  243  has a structure in which the semiconductor multilayer film  142 B in which the plural semiconductor layers having the semiconductor materials are stacked is formed on the semiconductor substrate  141 B and the dielectric multilayer film  144 B in which the plural dielectric layers having the dielectric materials are stacked is formed on the semiconductor multilayer film  142 B. An anti-reflection film (AR coating) may be formed on the surfaces of the face oriented toward the side of the light receiver  15  in the semiconductor substrate  141 B and the face oriented toward the side of the detection subject  21  in the dielectric multilayer film  144 B. 
     Effects of the photosensor  1  having the semiconductor band-pass filter  243  according to the second embodiment are similar to those of the photosensor  1  according to the first embodiment. 
     Further, according to the semiconductor band-pass filter  243  of the second embodiment, integration into one band-pass filter is allowed through forming the dielectric multilayer film  144 B on the semiconductor multilayer film  142 B. Moreover, the semiconductor band-pass filter  243  can suppress the noise component of the received light by cutting off ambient light in a wavelength band in which cutoff by the semiconductor multilayer film  142 B is not possible by use of the dielectric multilayer film  144 B having a high-pass filter or a low-pass filter. 
     Modification Example of Second Embodiment 
     (Configuration of Band-Pass Filter) 
     A band-pass filter  14 C according to a modification example of the second embodiment will be described. 
       FIG.  8    is one example of a configuration diagram illustrating the band-pass filter  14 C according to the modification example of the second embodiment. 
     The band-pass filter  14 C according to the modification example of the second embodiment has a different configuration with respect to the band-pass filter  14 B according to the second embodiment of  FIG.  7   . Specifically, the band-pass filter  14 B according to the second embodiment includes the semiconductor substrate  141 B that is one example of the base, the semiconductor multilayer film  142 B in which plural semiconductor layers having semiconductor materials are stacked, and the dielectric multilayer film  144 B in which plural dielectric layers having dielectric materials are stacked, whereas the band-pass filter  14 C according to the modification example of the second embodiment includes a semiconductor band-pass filter  244  as illustrated in  FIG.  8   . The configuration of the photosensor  1  other than the band-pass filter  14 C according to the modification example of the second embodiment is the same as the photosensor  1  according to the first embodiment. 
     Specifically, the semiconductor band-pass filter  244  includes a semiconductor substrate  141 C that is one example of the base, a semiconductor multilayer film  142 C that is one example of the first semiconductor multilayer film and in which plural semiconductor layers having semiconductor materials are stacked, and a semiconductor multilayer film  145 C that is one example of the second semiconductor multilayer film and in which plural semiconductor layers having semiconductor materials with different characteristics from the semiconductor multilayer film  142 C are stacked. 
     That is, the semiconductor band-pass filter  244  has a structure in which the semiconductor multilayer film  142 C in which the plural semiconductor layers having the semiconductor materials are stacked is formed on the semiconductor substrate  141 C and the semiconductor multilayer film  145 C in which the plural semiconductor layers having the semiconductor materials with different characteristics from the semiconductor multilayer film  142 C are stacked is formed on the semiconductor multilayer film  142 C. An anti-reflection film (AR coating) may be formed on the surfaces of the face oriented toward the side of the light receiver  15  in the semiconductor substrate  141 C and the face oriented toward the side of the detection subject  21  in the semiconductor multilayer film  145 C. 
     Effects of the photosensor  1  having the semiconductor band-pass filter  244  according to the modification example of the second embodiment are similar to those of the photosensor  1  according to the first embodiment. 
     Further, according to the semiconductor band-pass filter  244  of the modification example of the second embodiment, integration into one band-pass filter is allowed through forming the semiconductor multilayer film  145 C on the semiconductor multilayer film  142 C. Moreover, the semiconductor band-pass filter  244  can suppress the noise component of the received light by cutting off ambient light in a wavelength band in which cutoff by the semiconductor multilayer film  142 C is not possible by use of the semiconductor multilayer film  145 C having a high-pass filter or a low-pass filter. 
     Third Embodiment 
     (Configuration of Band-Pass Filter) 
     A band-pass filter  14 D according to a third embodiment will be described. 
       FIG.  9    is one example of a configuration diagram illustrating the band-pass filter  14 D according to the third embodiment. 
     The band-pass filter  14 D according to the third embodiment has a different configuration with respect to the band-pass filter  14 A of  FIG.  2    and the light receiver  15 . 
     Specifically, the band-pass filter  14  and the light receiver  15  are separately configured in the photosensor according to the first embodiment, whereas the band-pass filter  14 D according to the third embodiment includes a light receiver  15 D as illustrated in  FIG.  9   . The configuration of the photosensor  1  other than the band-pass filter  14 D and the light receiver  15 D according to the third embodiment is the same as the photosensor  1  according to the first embodiment. 
     Further, the band-pass filter  14 D includes the light receiver  15 D that is one example of the base, a semiconductor multilayer film  142 D that is one example of the first semiconductor multilayer film and in which plural semiconductor layers having semiconductor materials are stacked, and a dielectric multilayer film  144 D in which plural dielectric layers having dielectric materials are stacked. 
     That is, the band-pass filter  14 D has a structure in which the semiconductor multilayer film  142 D in which the plural semiconductor layers having the semiconductor materials are stacked is formed on the light receiver  15 D and the dielectric multilayer film  144 D in which the plural dielectric layers having the dielectric materials are stacked is formed on the semiconductor multilayer film  142 D. An anti-reflection film (AR coating) may be formed on the surface of the face oriented toward the side of the detection subject  21  in the dielectric multilayer film  144 D. 
     Effects of the photosensor  1  having the band-pass filter  14 D according to the third embodiment are similar to those of the photosensor  1  according to the first embodiment. 
     Further, according to the band-pass filter  14 D of the third embodiment, the band-pass filter and the light receiver can be integrated into one component through forming the semiconductor multilayer film  142 D and the dielectric multilayer film  144 D over the light receiver  15 D. Moreover, it is possible to suppress the noise component of the received light by cutting off ambient light in a wavelength band in which cutoff by the semiconductor multilayer film  142 D of the band-pass filter  14 D is not possible by use of the dielectric multilayer film  144 D having a high-pass filter or a low-pass filter. 
     Modification Example of Third Embodiment 
     (Configuration of Band-Pass Filter) 
     A band-pass filter  14 E according to a modification example of the third embodiment will be described. 
       FIG.  10    is one example of a configuration diagram illustrating the band-pass filter  14 E according to the modification example of the third embodiment. 
     The band-pass filter  14 E according to the modification example of the third embodiment has a different configuration with respect to the dielectric multilayer film  144 D according to the third embodiment of  FIG.  9   . 
     Specifically, as illustrated in  FIG.  10   , the band-pass filter  14 E according to the modification example of the third embodiment includes a semiconductor multilayer film  145 E in which plural semiconductor layers having semiconductor materials with different characteristics from a semiconductor multilayer film  142 E are stacked instead of the dielectric multilayer film  144 D according to the third embodiment. The configuration of the photosensor  1  other than the band-pass filter  14 E and the light receiver  15 E according to the modification example of the third embodiment is the same as the photosensor  1  according to the first embodiment. 
     Further, the band-pass filter  14 E includes a light receiver  15 E that is one example of the base, the semiconductor multilayer film  142 E that is one example of the first semiconductor multilayer film and in which plural semiconductor layers having semiconductor materials are stacked, and the semiconductor multilayer film  145 E that is one example of the second semiconductor multilayer film and in which the plural semiconductor layers having the semiconductor materials with different characteristics from the semiconductor multilayer film  142 E are stacked. 
     That is, the band-pass filter  14 E has a structure in which the semiconductor multilayer film  142 E in which the plural semiconductor layers having the semiconductor materials are stacked is formed on the light receiver  15 E and the semiconductor multilayer film  145 E in which the plural semiconductor layers having the semiconductor materials with different characteristics from the semiconductor multilayer film  142 E are stacked is formed on the semiconductor multilayer film  142 E. An anti-reflection film (AR coating) may be formed on the surface of the face oriented toward the side of the detection subject  21  in the semiconductor multilayer film  145 E. 
     Effects of the photosensor  1  having the band-pass filter  14 E according to the modification example of the third embodiment are similar to those of the photosensor  1  according to the first embodiment. 
     Further, according to the band-pass filter  14 E of the modification example of the third embodiment, the band-pass filter and the light receiver can be integrated into one component through forming the semiconductor multilayer film  142 E and the semiconductor multilayer film  145 E over the light receiver  15 E. Moreover, it is possible to suppress the noise component of the received light by cutting off ambient light in a wavelength band in which cutoff by the semiconductor multilayer film  142 E of the band-pass filter  14 E is not possible by use of the semiconductor multilayer film  145 E having a high-pass filter or a low-pass filter. 
     (Other Embodiments) 
     As described above, the embodiments have been described. However, statements and drawings that form part of the disclosure are exemplary ones and should not be understood as what impose a limitation. Various alternative embodiments, working examples, and operation techniques will become apparent for those skilled in the art from this disclosure. As above, the embodiments according to the present disclosure include various embodiments and other examples that are not described here.