Light detection device

Abstract

To provide a light detection device with good performance.SOLUTION: A light detection device according to an embodiment of the present disclosure comprises a splitter provided on a substrate and configured to transmit a light signal based on output light from a light source and a reference signal, a scanner provided on the substrate and configured to output the light signal transmitted from the splitter, and a light reception circuit provided on the substrate and configured to receive the light signal reflected from a target object and the reference signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a light detection device. [Background technology]

[0002] An optical coherence tomography (OCT) system having a photonic integrated circuit (PIC) has been proposed (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2014 / 0376001 Summary of the Invention [Problem to be solved by the invention]

[0004] In devices that detect light, it is desirable to be able to improve detection performance.

[0005] It is desirable to provide a photodetector device with good performance. [Means for solving the problem]

[0006] An optical detection device according to one embodiment of the present disclosure includes a splitter provided on a substrate and capable of transmitting an optical signal based on output light from a light source and a reference signal, a scanner provided on the substrate and capable of outputting the optical signal transmitted from the splitter, and an optical receiving circuit provided on the substrate and capable of receiving the optical signal reflected by an object and the reference signal. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a schematic configuration of a photodetector according to an embodiment of the present disclosure. [Figure 2]FIG. 2 is a diagram illustrating an example of a signal generated by the photodetector according to the embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram illustrating an example of a cross-sectional configuration of a photodetector according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram illustrating a configuration example of a photodetector according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram illustrating another configuration example of a photodetector according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram illustrating another configuration example of a photodetector according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram illustrating an example of the arrangement of antennas in a photodetector according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram illustrating an example of the arrangement of antennas in a photodetector according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram illustrating an example of the arrangement of antennas in a photodetector according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram illustrating an example of the arrangement of antennas in a photodetector according to an embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram illustrating a configuration example of a photodetector according to an embodiment of the present disclosure. [Figure 12] FIG. 12 is a diagram illustrating a configuration example of a photodetector according to an embodiment of the present disclosure. [Figure 13] FIG. 13 is a diagram illustrating another configuration example of a photodetector according to an embodiment of the present disclosure. [Figure 14] FIG. 14 is a diagram illustrating another configuration example of a photodetector according to an embodiment of the present disclosure. [Figure 15A] FIG. 15A illustrates an example of a method for manufacturing a photodetector according to an embodiment of the present disclosure. [Figure 15B] FIG. 15B illustrates an example of a method for manufacturing a photodetector according to an embodiment of the present disclosure. [Figure 15C]FIG. 15C illustrates an example of a method for manufacturing a photodetector according to an embodiment of the present disclosure. [Figure 15D] FIG. 15D illustrates an example of a method for manufacturing a photodetector according to an embodiment of the present disclosure. [Figure 15E] FIG. 15E is a diagram illustrating an example of a method for manufacturing a photodetector according to an embodiment of the present disclosure. [Figure 15F] FIG. 15F is a diagram illustrating an example of a method for manufacturing a photodetector according to an embodiment of the present disclosure. [Figure 16] FIG. 16 is a diagram illustrating a configuration example of a photodetector according to the first modification of the present disclosure. [Figure 17] FIG. 17 is a diagram illustrating a configuration example of a photodetector according to the second modification of the present disclosure. [Figure 18] FIG. 18 is a diagram illustrating a configuration example of a photodetector according to a third modification of the present disclosure. [Figure 19] FIG. 19 is a diagram illustrating a configuration example of a photodetector according to a fourth modification of the present disclosure. [Figure 20] FIG. 20 is a diagram illustrating a configuration example of a photodetector according to a fifth modification of the present disclosure. [Figure 21] FIG. 21 is a diagram illustrating a configuration example of a photodetector according to a sixth modification of the present disclosure. [Figure 22] FIG. 22 is a diagram illustrating a configuration example of a photodetector according to a sixth modification of the present disclosure. [Figure 23] FIG. 23 is a diagram illustrating a configuration example of a photodetector according to a seventh modification of the present disclosure. [Figure 24] FIG. 24 is a diagram illustrating a configuration example of a photodetector according to a seventh modification of the present disclosure. [Figure 25] FIG. 25 is a diagram illustrating a configuration example of a photodetector according to Modification 8 of the present disclosure. [Figure 26] FIG. 26 is a diagram illustrating a configuration example of a photodetector according to Modification 8 of the present disclosure. [Figure 27] FIG. 27 is a diagram showing an example of a schematic configuration of an endoscopic surgery system. [Figure 28]FIG. 28 is a block diagram showing an example of the functional configuration of the camera head and the CCU. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order. 1. Embodiment 2. Variations 3. Usage example 4. Application Examples

[0009] <1. Embodiment> FIG. 1 is a diagram illustrating an example of a schematic configuration of a photodetector according to an embodiment of the present disclosure. The photodetector 1 is a device capable of detecting incident light. The photodetector 1 can be configured as a device capable of performing distance measurement, i.e., a distance measuring device. The photodetector 1 (distance measuring device) can perform distance measurement and generate a tomographic image using optical interference, for example.

[0010] The light detection device 1 is configured to be able to measure biomarkers such as heart rate, blood flow, and blood components using, for example, OCT (Optical Coherence Tomography) technology. The light detection device 1 can be configured as a blood component sensor. Examples of blood components include glucose, lactic acid, triglycerides, and fatty acids. The light detection device 1 acquires signals (information) related to the state of the living body, making it possible to confirm the state of the living body.

[0011] The light detection device 1 is applied, for example, as an OCT device. The light detection device 1 is applied as an optical coherence tomograph, and can also be called an optical coherence tomography imaging device (or optical coherence tomography device). The light detection device 1 can be used, for example, in electronic devices that are worn by a user. The light detection device 1 may be applied to devices that can be worn on the body, such as the hand, wrist, arm, or leg, and may be realized as a device installed in a wearable device.

[0012] The photodetector 1 transmits and receives optical signals that become frequency-modulated light, and can measure the distance to an object, an image of the object, and the like. The photodetector 1 has, for example, a photonic integrated circuit (PIC). The photodetector 1 can be manufactured using a silicon-containing substrate (such as a silicon substrate or an SOI (Silicon On Insulator) substrate) and silicon photonics technology. The photodetector 1 has, for example, a structure (layered structure) formed by stacking multiple substrates.

[0013] 1, the photodetector 1 includes, for example, a light source 10, an optical circuit 50 including a scanner 30 and a light-receiving circuit 40, an amplifier circuit 60, and a signal processing circuit 70. The photodetector 1 can irradiate an object (e.g., skin) with an optical signal that has been frequency-modulated by the light source 10 and the scanner 30, and receive an optical signal reflected by the object. As an example, the photodetector 1 irradiates skin, which is the measurement object, with an optical signal (laser light), and receives an optical signal that has been reflected and delayed by a layer within the skin.

[0014] In the photodetector 1, for example, a reference light branched (separated) from the output light of the light source 10 and a reflected light (returned light) reflected by the measurement object are incident (input) on the light receiving circuit 40, and an electrical signal having a frequency corresponding to the frequency of the reference light and the frequency of the reflected light is detected. The electrical signal generated by receiving the reflected light from the measurement object is, for example, a beat signal having a frequency corresponding to the difference between the frequency of the reference light and the frequency of the reflected light, and is a signal corresponding to the distance to the measurement object.

[0015] The optical circuit 50, the amplifier circuit 60, the signal processing circuit 70, etc. may be provided on a single substrate (e.g., a semiconductor substrate such as a silicon substrate or an SOI substrate). The optical circuit 50, the amplifier circuit 60, the signal processing circuit 70, etc. may be provided separately on multiple layers. The photodetector 1 may have a layered structure formed by stacking multiple substrates.

[0016] The light source 10 is provided, for example, on the same substrate as the scanner 30 and the light receiving circuit 40, and is mounted on the photodetector 1. The light source 10 may be provided outside the photodetector 1. The photodetector (photodetector 1) may be configured as a photodetection system including the light source 10, an optical circuit 50, an amplifier circuit 60, a signal processing circuit 70, and the like.

[0017] The light source 10 is configured to be able to generate an optical signal. The light source 10 has, for example, a light emitting element and is configured to be able to output an optical signal (laser light). The light source 10 has, as an example, a tunable laser light source and outputs output light that becomes a frequency-modulated optical signal to a measurement target via an optical circuit 50. The light source 10 is, as an example, configured using a III-V compound semiconductor material (InP, GaAs, etc.), and has a configuration in which a p-type cladding layer, an active layer, and an n-type cladding layer are stacked.

[0018] The light source 10 can generate and emit frequency-modulated laser light. That is, the light source 10 can generate and output a signal (chirp signal) whose frequency changes continuously over time. The light source 10 may be configured using a semiconductor optical amplifier (SOA).

[0019] The optical circuit 50 includes, for example, a splitter 20, a scanner 30, and a light receiving circuit 40. The output light of the light source 10 (for example, frequency-modulated laser light) is input (incident) to the splitter 20. For example, the output light of the light source 10 is split (separated) by the splitter 20. The splitter 20 is configured to transmit an optical signal based on the output light of the light source 10 and a reference signal.

[0020] 1, an optical signal S1, which is a part of the output light from the light source 10, is transmitted to the scanner 30 by the splitter 20. An optical signal (referred to as a reference signal S2), which is another part of the output light from the light source 10, is transmitted to the light receiving circuit 40. For example, the reference signal S2, which has a power equal to or less than 50% of the power (amount of light) of the output light from the light source 10, is split from the output light from the light source 10 and input (incident) to the light receiving circuit 40 as reference light (local light).

[0021] The scanner 30 is configured to be able to output (transmit) an optical signal. For example, the scanner 30 is configured to output an optical signal transmitted from the light source 10 via the splitter 20 to the outside. In the example shown in FIG. 1 , a frequency-modulated optical signal S1 is propagated from the splitter 20 to the scanner 30. The scanner 30 can emit the optical signal S1, which is a frequency-modulated laser light, to a measurement target as output light (i.e., transmitted light, irradiated light).

[0022] The scanner 30 is also configured to receive (receive) an optical signal reflected by the measurement object. For example, the scanner 30 can receive an optical signal S3, which is a laser beam reflected and delayed by the measurement object. The scanner 30 outputs the optical signal S3, which is the reflected light (i.e., received light), to the light receiving circuit 40 via the splitter 20.

[0023] The scanner 30 includes, for example, a plurality of switch units 31 and an antenna 32. The antenna 32 is configured to be capable of outputting an optical signal. The antenna 32 is also configured to be capable of receiving an optical signal reflected by a measurement target. The antenna 32 is a transmitting antenna configured to be capable of transmitting an optical signal, and is also a receiving antenna configured to be capable of receiving an optical signal.

[0024] The antenna 32 is configured by, for example, a diffraction grating. As an example, the antenna 32 is formed using Si (silicon) and configured as a transmitting / receiving antenna. The antenna 32 can irradiate a measurement object with frequency-modulated laser light and receive the laser light reflected and delayed by the measurement object.

[0025] The switch unit 31 has a plurality of switches (optical switches) provided corresponding to the plurality of antennas 32, and is configured to be able to select the antenna 32 to which the optical signal S1 is to be transmitted from the splitter 20. By switching the transmission path of the optical signal S1 using the switch unit 31, the antenna 32 that emits the optical signal S1 is changed, and the emission direction (travel direction) of the optical signal S1 is changed.

[0026] The light receiving circuit 40 is configured to be able to receive an optical signal reflected by an object and a reference light. The light receiving circuit 40 is configured to include, for example, a mixer 41 and a light receiving unit 45. The mixer 41 is configured to be able to mix the optical signal reflected by the object to be measured and the reference signal. The mixer 41 (mixer) is configured to, for example, mix the reference light and the reflected light and output the mixed optical signal.

[0027] 1, the mixer 41 is configured to mix a reference signal S2, which is reference light input from the light source 10 and the splitter 20, with an optical signal S3, which is reflected light (i.e., received light) input from the scanner 30 and the splitter 20. The mixer 41 can transmit an optical signal obtained by mixing the reference light and the reflected light to the light receiving unit 45.

[0028] The light receiving circuit 40 is configured to be able to, for example, cause the reference light and the reflected light to interfere with each other and generate interfered light (interference light). The light receiving circuit 40 can generate an optical signal by combining (combining) the reference signal S2 and the optical signal S3, which is the reflected light, and output the optical signal to the light receiving unit 45.

[0029] The light receiving circuit 40 has a light receiving unit 45 including a light receiving element 46 (light receiving element 46a and light receiving element 46b in FIG. 1). The light receiving element 46 is, for example, a photodiode (PD) and is configured to be able to receive an optical signal. The light receiving circuit 40 is configured to receive the optical signal and convert the optical signal into an electrical signal.

[0030] 1, the light receiving unit 45 has a light receiving element 46a and a light receiving element 46b, which are balanced photodiodes. The light receiving element 46a and the light receiving element 46b are electrically connected in series. The light receiving element 46a and the light receiving element 46b are configured to receive an optical signal via, for example, a mixer 41.

[0031] The light receiving element 46 (light receiving elements 46a and 46b in FIG. 1) receives light, generates charges through photoelectric conversion, and can output a current. The light receiving element 46 is configured to be able to output a signal based on the reference signal S2 and the optical signal S3 reflected by an object. For example, in response to receiving an optical signal obtained by mixing the reference signal S2 and the optical signal S3, which is the reflected light, a signal corresponding to the photocurrent flowing through the light receiving unit 45 is generated and output to the amplifier circuit 60.

[0032] The amplifier circuit 60 is, for example, electrically connected to the light receiving unit 45 and configured to be able to output a signal based on the photocurrent generated by the light receiving unit 45. The amplifier circuit 60 is provided for the light receiving elements 46a and 46b and configured to output a signal S4 based on the photocurrent generated by the light receiving elements 46a and 46b. The amplifier circuit 60 includes, for example, a transimpedance amplifier (TIA) and is configured to convert the current signal into a voltage signal.

[0033] 1, the amplifier circuit 60 is electrically connected to the node connecting the light receiving element 46a and the light receiving element 46b. The amplifier circuit 60 converts the current signal detected by the light receiving unit 45 into a voltage signal and outputs the voltage signal S4 to the signal processing circuit 70. The signal S4 has a frequency corresponding to the frequency difference between the optical signal S1 (and the reference signal S2) and the optical signal S3, for example. The signal S4 can also be called an interference signal or a beat signal.

[0034] The amplifier circuit 60 can also be considered a detection circuit that can output an electrical signal based on an optical signal. The amplifier circuit 60 can be configured, for example, as described above, with a TIA circuit, and can output a signal S4, which is a voltage signal corresponding to the optical signal received by the light receiving unit 45, to the signal processing circuit 70. The amplifier circuit 60 and the light receiving unit 45 can also be collectively called a detection circuit.

[0035] Fig. 2 is a diagram illustrating an example of a signal generated by a photodetector according to an embodiment. In Fig. 2, the vertical axis represents the frequency f of an optical signal, which is a chirp signal, and the horizontal axis represents time t. Fig. 2 shows an optical signal S1, which is light transmitted to an object to be measured, and an optical signal S3, which is light received from the object to be measured.

[0036] In the light receiving circuit 40, a reference optical signal corresponding to the transmitted optical signal S1, i.e., interference light generated by mixing the reference signal S2 and the optical signal S3, is output by the mixer 41 to the light receiving unit 45. The light receiving circuit 40 receives the interference light from the mixer 41 by the light receiving unit 45, and can generate and output a signal S4. In the photodetector 1, the signal S4 can be used to determine the distance to the measurement target, etc.

[0037] The signal processing circuit 70 is configured to be able to perform signal processing. The signal processing circuit 70 is configured by circuits that perform various types of signal processing on signals input from the amplifier circuit 60. The signal processing circuit 70 is configured to include an arithmetic circuit, a memory circuit, etc. The signal processing circuit 70 (signal processing unit) may include a processor and a memory.

[0038] The signal processing circuit 70 includes, for example, an AD conversion circuit 71 and an arithmetic circuit 72. The AD conversion circuit 71 is configured to be able to perform AD (Analog-to-Digital) conversion and converts an input analog signal into a digital signal. The AD conversion circuit 71 is an ADC (Analog to Digital Converter). A signal S4, which is an interference signal (beat signal), is input to the AD conversion circuit 71 from, for example, the amplifier circuit 60.

[0039] The AD conversion circuit 71 performs AD conversion processing on the signal S4, which is an analog signal input from the amplifier circuit 60. The AD conversion circuit 71 (AD conversion unit) may, for example, sample the signal S4 and convert the analog signal S4 into a digital signal. The AD conversion circuit 71 outputs the signal S4, which has been converted into a digital signal for each sampling point, to the arithmetic circuit 72.

[0040] The arithmetic circuit 72 is configured to acquire the signal S4 converted into a digital signal and perform arithmetic processing. The arithmetic circuit 72 (arithmetic unit) is configured, for example, by a logic circuit, a memory, etc. The arithmetic circuit 72 is configured to perform frequency analysis processing on the signal S4. The arithmetic circuit 72 can also be said to be an analysis unit configured to analyze the signal S4.

[0041] The arithmetic circuit 72 obtains the distance to the measurement target, an image of the measurement target, etc. by, for example, performing an FFT (Fast Fourier Transform) on the signal S4. As an example, the signal processing circuit 70 calculates the distance to the measurement target based on the frequency (e.g., beat frequency) of the signal S4 when the frequency of the laser light is increased (or decreased) over time.

[0042] The signal processing circuit 70 can generate signals related to the distance to the target, signals related to the image of the target, etc., and output them to the outside of the photodetector 1. The signal processing circuit 70 also functions as a control unit (control circuit) and is configured to be able to control each unit of the photodetector 1. The signal processing circuit 70 can include circuits such as a PLL (Phase Locked Loop) and a DAC (Digital to Analog Converter).

[0043] The signal processing circuit 70 is configured to, for example, supply a signal for controlling the light source 10 to the light source 10, thereby controlling the light source 10. Furthermore, for example, the signal processing circuit 70 is configured to be able to control the scanning of the optical signal by the scanner 30, the generation process of the interference signal (beat signal) by the light receiving circuit 40, the AD conversion process by the AD conversion circuit 71, etc.

[0044] 3 is a diagram showing an example of a cross-sectional configuration of a photodetector 1 according to an embodiment. The photodetector 1 is configured using a substrate 101 containing silicon. The substrate 101 is configured by a semiconductor substrate such as an SOI (Silicon On Insulator) substrate or a silicon substrate.

[0045] 3, the substrate 101 is configured to include a layer 110, an insulating layer 105, a layer 120, and a wiring layer 90. The layers 110 and 120 are, for example, semiconductor layers, and are also referred to as the semiconductor layer 110 and the semiconductor layer 120. As an example, the semiconductor layer 110 and the semiconductor layer 120 are silicon layers, and the insulating layer 105 is a BOX (Buried Oxide) layer.

[0046] Note that the layers 110 and 120 may each be made of another semiconductor material or other materials. For example, the layer 110 (or layer 120) that serves as a waveguide may be made of a material (such as silicon nitride) that has a refractive index higher than that of the surrounding material and transmits an optical signal (laser light).

[0047] The photodetector 1 has a configuration in which, for example, a wiring layer 90, a semiconductor layer 110, an insulating layer 105, and a semiconductor layer 120 are stacked in the Z-axis direction. As shown in Fig. 3, the direction perpendicular to the Z-axis direction is the X-axis direction, and the direction perpendicular to the Z-axis and X-axis directions is the Y-axis direction. In the following figures, directions may be indicated based on the direction of the arrow in Fig. 3.

[0048] 3, the semiconductor layer 110 has opposing surfaces 11S1 and 11S2. The surface 11S2 is the surface opposite to the surface 11S1. An insulating layer 105 is provided on the surface 11S2 side of the semiconductor layer 110. A wiring layer 90 is provided on the surface 11S1 side of the semiconductor layer 110. The semiconductor layer 110 and the wiring layer 90 of the substrate 101 are provided with the optical circuit 50, the light-receiving circuit 40, and the like described above.

[0049] For example, a scanner 30 including a plurality of antennas 32, a light receiving unit 45 including a light receiving element 46 (light receiving element 46a and light receiving element 46b in FIG. 1), etc. are formed on the surface 11S1 side of the semiconductor layer 110. It can also be said that the optical circuit 50, the light receiving unit 45, etc. are provided on the semiconductor layer 110.

[0050] The light receiving element 46 is configured by, for example, a germanium photodiode (GePD) and is provided on the surface 11S1 of the semiconductor layer 110. The amplifier circuit 60 and the signal processing circuit 70 described above may be provided in the semiconductor layer 110 and the wiring layer 90, or in a semiconductor layer other than the semiconductor layer 110.

[0051] The wiring layer 90 includes, for example, a conductor film and an insulating film, and has a plurality of wires and vias. The wiring layer 90 has, for example, a configuration in which a plurality of wires are stacked with an insulating film interposed therebetween as an interlayer insulating film. The wiring layer 90 is a multi-layer wiring layer, and includes, for example, two or more layers of wires, or three or more layers of wires.

[0052] The wiring of the wiring layer 90 is formed using a metal material such as aluminum (Al), tungsten (W), or copper (Cu). The wiring of the wiring layer 90 may be made of polysilicon (Poly-Si) or other conductive materials. The interlayer insulating film is formed using, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), or the like.

[0053] A scanner 30 including a plurality of antennas 32 and a heater 38 is provided on the substrate 101. The antennas 32 are formed on the semiconductor layer 110, for example, as shown in the example of FIG. 3. The plurality of antennas 32 are provided along the surfaces 11S1 and 11S2 of the semiconductor layer 110. On the substrate 101, the plurality of antennas 32 are arranged, for example, aligned in the X-axis direction and the Y-axis direction. The scanner 30 may have an antenna array including the plurality of antennas 32.

[0054] The antenna 32 is configured, for example, by a waveguide provided with a plurality of holes (perforations) penetrating the semiconductor layer 110, a waveguide provided with a plurality of grooves, or the like. The antenna 32 may be configured by a diffraction grating provided in the waveguide. As an example, the antenna 32 has a diffraction grating configured using a periodically formed pattern (for example, a pattern of circular holes).

[0055] The heater 38 is provided, for example, around the switch (i.e., the optical switch) of the switch section 31 described above, and is configured to be able to heat the switch of the switch section 31. The heater 38 is configured, for example, using a resistive element (resistor), and is provided for each optical switch or for each set of multiple optical switches. As an example, as schematically shown in FIG. 3, the heater 38 (heater section) is electrically connected to vias, wiring, etc. of the wiring layer 90, and is configured to be able to conduct electricity.

[0056] In the scanner 30, the refractive index of the waveguide of the optical switch is changed by applying heat to the optical switch by supplying a current to the heater 38, thereby switching the antenna 32 to which the optical signal S1 is transmitted. For example, the signal processing circuit 70 can change the antenna 32 (i.e., the diffraction grating) that emits the optical signal S1 by controlling the supply of a current to the heater 38.

[0057] Furthermore, for example, the heater 38 may be provided around the antenna 32 and configured to be able to heat the antenna 32. The signal processing circuit 70 may change the refractive index of the antenna 32 by controlling the temperature using the heater 38, thereby fine-tuning the direction of the optical signal S1 emitted from the antenna 32 (i.e., the diffraction grating). The heater 38 may be provided for each antenna 32 or for each of multiple antennas 32.

[0058] The photodetector 1 is also provided with the above-described light source 10 and waveguide 15. The light source 10 is disposed on the substrate 101 so as to be located on the side surface of the semiconductor layer 110, for example. In the example shown in FIG. 3, the light source 10 is disposed above the semiconductor layer 120 so that output light (optical signal) of the light source 10 enters the waveguide 15. The light source 10 is also electrically connected to a circuit that controls the light source 10, for example, by electrodes 91 and 92.

[0059] The waveguide 15 is, for example, a Si (silicon) waveguide and is provided in the semiconductor layer 110. The waveguide 15 is configured to guide an input (incident) optical signal. The waveguide 15 may be made of other semiconductor materials or other materials (e.g., silicon nitride). The waveguide 15 may be formed using other materials having a refractive index higher than that of surrounding members (e.g., the insulating film of the wiring layer 90 or the insulating layer 105).

[0060] The waveguide 15 may be provided between the light source 10 and the splitter 20, between the splitter 20 and the scanner 30, or between the splitter 20 and the light receiving circuit 40. In the example shown in Fig. 3, the waveguide 15 is configured to transmit (propagate) an optical signal from the light source 10 side to the scanner 30 side, for example.

[0061] 3, the scanner 30 of the light detection device 1 has a light collecting element 35. The light collecting element 35 is configured with, for example, a lens 36, and is provided above the antenna 32. The light collecting element 35 is an optical member that collects light (transmitted light) from the antenna 32, and can also be called a light guiding element. The light collecting element 35 also guides reflected light (returned light) from the measurement target toward the antenna 32.

[0062] As shown in the example of FIG. 3, a light-collecting element 35 (lens 36) is provided for each antenna 32. As an example, the lens 36 is provided so as to be stacked on the wiring layer 90, and is located above the antenna 32. The antenna 32 can transmit and receive optical signals via the lens 36. In the photodetector 1, for example, a plurality of lenses 36 are arranged so as to be aligned in the X-axis direction and the Y-axis direction. The scanner 30 can have a microlens array including a plurality of lenses 36 (microlenses).

[0063] The lens 36 is made of, for example, a resin material, a glass material, or the like. The lens 36 may be made of silicon oxide (SiO), silicon nitride (SiN), amorphous silicon (a-Si), or other materials. The configuration (shape, size, etc.) of the lens 36 is not limited to the example shown in the drawings and can be changed as appropriate.

[0064] The light-collecting element 35 may have a plurality of structures (e.g., high-refractive index members) and may be configured to collect light. The light-collecting element 35 may be an optical element configured using nanostructures, and may be configured as a metalens (metamaterial lens). The metalens serving as the light-collecting element 35 may be formed using, for example, a metal, a metal compound (e.g., a metal oxide, a metal nitride), a silicon compound, or other materials.

[0065] As described above, the photodetector 1 according to this embodiment has the splitter 20, the scanner 30, and the light receiving circuit 40, which are each provided on the substrate 101. This makes it possible to realize a photodetector 1 with good detection performance. For example, it is possible to realize a photodetector (distance measuring device) with performance suitable for an OCT device.

[0066] 3, in the light detection device 1, a light collecting element 35 can be provided for each antenna 32. One light collecting element 35 (for example, a lens 36) is provided for one antenna 32. This allows light (optical signal) to be appropriately guided toward the measurement target, thereby improving measurement accuracy.

[0067] 3, the photodetector 1 may also have a spacer layer 95. The spacer layer 95 is provided, for example, between the light-collecting element 35 and the wiring layer 90. The spacer layer 95 is, for example, made of the same material as the lens 36 and is located between the lens 36 and the antenna 32. The spacer layer 95 may also be made of a material different from that of the lens 36.

[0068] The thickness (height) of the spacer layer 95 can be set so that light from the antenna 32 is focused on the measurement target. For example, the thickness (height) of the spacer layer 95 in the Z-axis direction is determined so that the focus is on the living body (skin) that is the measurement target. This makes it possible to efficiently focus light on the measurement target, thereby improving measurement accuracy.

[0069] Fig. 4 is a diagram showing an example of the configuration of a photodetector according to an embodiment. In the example shown in Fig. 4, the photodetector 1 has a plurality of light sources 10 (light source 10a, light source 10b, light source 10c, and light source 10d in Fig. 4). The light sources 10a to 10d can be configured to generate and output optical signals in different wavelength bands.

[0070] For example, light source 10a is configured to be able to generate output light in wavelength band A, and light source 10b is configured to be able to generate output light in wavelength band B. Furthermore, light source 10c is configured to be able to generate output light in wavelength band C, and light source 10d is configured to be able to generate output light in wavelength band D. Note that wavelength bands A to D may be set so that the wavelength bands partially overlap.

[0071] The optical circuit 50 is provided, for example, in common to the plurality of light sources 10. In the example shown in Fig. 4, one optical circuit 50 is provided for the light sources 10a to 10d. The optical circuit 50 is configured to transmit and receive optical signals using laser light input from the light sources 10a to 10d via the waveguide element 12, for example.

[0072] The waveguide element 12 is configured to transmit, for example, at least one of the output lights of the light sources 10a to 10d to the optical circuit 50. As an example, the waveguide element 12 can selectively output any one of the output light from the light source 10a, the output light from the light source 10b, the output light from the light source 10c, and the output light from the light source 10d.

[0073] Furthermore, for example, the waveguide element 12 may be configured to transmit an optical signal obtained by multiplexing (combining) the output light beams from the light sources 10a to 10d, which are emitted in a time-division manner, to the splitter 20 of the optical circuit 50. The waveguide element 12 can also be called a multiplexing element. Note that the optical circuit 50 may be configured to include the waveguide element 12 (multiplexing element).

[0074] As described above, the photodetector 1 has multiple light sources 10 and is configured to be able to perform measurements using optical signals in different wavelength ranges. Therefore, for example, it is possible to obtain information for each wavelength as a measurement result, thereby improving measurement accuracy. It is possible to perform distance measurement with high accuracy. It is also possible to measure multiple biomarkers.

[0075] The signal processing circuit 70 of the photodetector 1 may be configured to combine (synthesize) signals (information) obtained as measurement results by transmitting and receiving optical signals of each wavelength band. This makes it possible to improve the resolution in the planar direction or depth direction. For example, this can improve the distance measurement accuracy and the resolution of tomographic images.

[0076] 4, by transmitting and receiving optical signals in each wavelength range via the scanner 30 of the common optical circuit 50, it is possible to prevent deviations in the irradiation position of the optical signal (beam). This makes it possible to prevent, for example, a decrease in the accuracy of biomarker identification.

[0077] Fig. 5 is a diagram showing another example of the configuration of the photodetector according to the embodiment. An optical circuit 50 may be provided for each light source 10. In the example shown in Fig. 5, one optical circuit 50 is provided for one light source 10. The optical circuit 50 is configured to transmit and receive optical signals using, for example, laser light input from the corresponding light source 10.

[0078] 5, when an optical circuit 50 is provided for each light source 10, the optical circuit 50 can be configured to have optical characteristics suitable for the wavelength band of the output light of the corresponding light source 10, thereby reducing light loss. For example, it becomes possible to prevent a decrease in the S / N ratio of the optical signal due to the wavelength dependency of the characteristics of the optical circuit 50.

[0079] 6 is a diagram showing another example of the configuration of a photodetector according to an embodiment. A common optical circuit 50 may be provided for a plurality of light sources 10 (light source 10a and light source 10b in FIG. 6) that output optical signals in relatively close wavelength bands. Alternatively, separate optical circuits 50 may be provided for a plurality of light sources 10 (light source 10c and light source 10d in FIG. 6) that output optical signals in relatively distant wavelength bands.

[0080] 7 to 10 are diagrams illustrating examples of the arrangement of antennas in a photodetector according to an embodiment. Figures 7 to 10 show examples of the arrangement of antennas 32 of each optical circuit 50 when the photodetector 1 has a plurality of optical circuits 50 (for example, optical circuits 50a to 50d).

[0081] In each figure, the antenna 32 (antenna 32a) of the optical circuit 50a, the antenna 32 (antenna 32b) of the optical circuit 50b, the antenna 32 (antenna 32c) of the optical circuit 50c, and the antenna 32 (antenna 32d) of the optical circuit 50d are shown.

[0082] The multiple antennas 32a connected to the switch unit 31 of the optical circuit 50a and the multiple antennas 32b connected to the switch unit 31 of the optical circuit 50b may be arranged, for example, as shown in Fig. 7. Some of the multiple antennas 32a are provided between adjacent multiple antennas 32b.

[0083] 7, some of the antennas 32b are provided between adjacent antennas 32a. The antennas 32a and 32b may be provided in a checkerboard pattern, for example. The antennas 32a and 32b may be provided alternately.

[0084] In the photodetector 1, a plurality of antennas 32a aligned in the Y-axis direction (or the X-axis direction) and a plurality of antennas 32b aligned in the Y-axis direction (or the X-axis direction) may be arranged alternately as in the example shown in Fig. 8. By arranging the antennas 32a and 32b as in the example shown in Fig. 7 or 8, it is possible to suppress deviation in the irradiation position of the optical signal.

[0085] 9, the antennas 32a, 32b, 32c, and 32d may be mixed together. For example, the photodetector 1 may have a row 115 in which the antennas 32a and 32b are alternately arranged, and a row 116 in which the antennas 32c and 32d are alternately arranged.

[0086] In the photodetector 1, for example, a plurality of waveguides may be provided so as to intersect with each other in correspondence with the arrangement positions of the antennas 32 (e.g., antennas 32a to 32d). Alternatively, for example, a waveguide having a two-layer structure may be provided. The antennas 32a to 32d may be provided in equal numbers, or may be provided in different numbers.

[0087] As shown in the example of Fig. 10, the number of antennas 32c may be different from the number of antennas 32a (or antennas 32b). In the example of Fig. 10, the photodetector 1 has a row 117 in which the antennas 32a and 32c are alternately arranged, and a row 118 in which the antennas 32c and 32b are alternately arranged.

[0088] When measuring a biomarker that requires a high S / N ratio using optical signals transmitted and received via a specific antenna, for example, antenna 32c, more antennas 32c may be provided than other antennas (for example, antennas 32a and 32b). In the example shown in Fig. 10, the number of antennas 32c is greater than the number of antennas 32a and the number of antennas 32b.

[0089] 11 and 12 are diagrams illustrating an example of the configuration of a photodetector according to an embodiment. Fig. 11 shows an example of the cross-sectional configuration of the photodetector, and Fig. 12 shows an example of the planar configuration of a scanner of the photodetector. The photodetector 1 can be configured so that the straight line passing through the center of the antenna 32 is misaligned with the optical axis of the light-collecting element 35.

[0090] The photodetector 1 is configured, for example, so that the optical axis L1 of the lens 36 serving as the light-collecting element 35 is deviated from a line L2 passing through the center of the antenna 32. For example, the optical axis L1 of the lens 36 is positioned so as to be deviated in the X-axis direction (or Y-axis direction) from the line L2 passing through the center of the antenna 32 (i.e., the diffraction grating).

[0091] 11, the lens 36 is provided so that the optical axis L1 of the lens 36 is shifted horizontally (e.g., leftward) with respect to the center line L2 of the antenna 32. By configuring the photodetector 1 in this manner, it becomes possible to appropriately guide the oblique light emitted from the antenna 32 to the measurement target, as schematically shown by the solid arrow in FIG.

[0092] The transmitted light traveling in an oblique direction from the antenna 32 is corrected by the lens 36 so that it travels, for example, vertically (in the Z-axis direction), and the transmitted light (i.e., the optical signal S1) can be efficiently guided to the measurement target (for example, skin). This makes it possible to achieve a short working distance (for example, the distance from the photodetector 1 to the skin as the measurement target).

[0093] The photodetector 1 according to this embodiment makes it possible to realize a wearable device that can accommodate a short working distance. Furthermore, by configuring the photodetector 1 as described above, it is possible to make the transmitted light perpendicularly incident on the skin as the measurement target, enabling sensing of deep regions.

[0094] 13 is a diagram illustrating another example of the configuration of a photodetector according to an embodiment. The photodetector 1 may be configured so that the optical axis of the light-collecting element 35 is tilted with respect to a line passing through the center of the antenna 32. For example, a lens 36 serving as the light-collecting element 35 is provided so that the optical axis L1 of the lens 36 is tilted with respect to the center line L2 of the antenna 32 (i.e., the diffraction grating).

[0095] 13, the lens 36 may be disposed obliquely (tilted) so that the oblique light emitted from the antenna 32 passes through the center of the lens 36. By configuring the photodetector 1 in this manner, it becomes possible to efficiently collect the oblique light emitted from the antenna 32. This improves the light collection efficiency and improves the sensitivity.

[0096] Furthermore, the transmitted light can be made obliquely incident on the skin as the measurement target, which makes it possible to reduce the reflected light (received light) from the surface of the skin. As a result, for example, noise components caused by the reflected light on the surface of the skin can be reduced, enabling accurate sensing of blood components.

[0097] Fig. 14 is a diagram illustrating another example of the configuration of the photodetector according to the embodiment. Fig. 14 shows an example of the arrangement of the antenna 32 and the lens 36 of each optical circuit 50 when the photodetector 1 has a plurality of optical circuits 50 (for example, optical circuit 50a, optical circuit 50b).

[0098] FIG. 14 also illustrates the antenna 32a of the optical circuit 50a, the center line L2a of the antenna 32a, the lens 36a of the optical circuit 50a, the optical axis L1a of the lens 36a, the antenna 32b of the optical circuit 50b, the center line L2b of the antenna 32b, the lens 36b of the optical circuit 50b, and the optical axis L1b of the lens 36b.

[0099] In the photodetector 1, the antennas 32 and lenses 36 of each optical circuit 50 may be provided so that transmitted light of different wavelengths overlaps. For example, as shown in Fig. 14, the photodetector 1 is configured so that the irradiation position of the transmitted light of wavelength A1 output from antenna 32a and the irradiation position of the transmitted light of wavelength B1 output from antenna 32b are approximately the same. This makes it possible to suppress misalignment of the irradiation positions of the optical signals of each wavelength.

[0100] 15A to 15F are diagrams showing an example of a method for manufacturing a photodetector according to an embodiment. First, as shown in FIG. 15A, a substrate 101 such as an SOI substrate is prepared. Next, as shown in FIG. 15B, a waveguide 15, an antenna 32, etc. are formed in a semiconductor layer 110 of the substrate 101. Then, as shown in FIG. 15C, a light receiving element 46, a heater 38, etc. are formed in this order on the surface 11S1 side of the semiconductor layer 110, and a wiring layer 90 is formed.

[0101] 15D, portions of the wiring layer 90, the semiconductor layer 110, and the insulating layer 105 are removed by lithography and dry etching. After a region for the light source 10 is formed by partially removing the wiring layer 90, the insulating layer 105, etc., an electrode 92 is formed on the semiconductor layer 120 as shown in FIG.

[0102] Next, as shown in Fig. 15E, the light source 10 having the electrode 91 is flip-chip connected to the substrate 101 on which the electrode 92 is provided. Then, as shown in Fig. 15F, the spacer layer 95, the lens 36, etc. are formed. By the manufacturing method described above, the photodetector 1 shown in Fig. 3 etc. can be manufactured. Note that the manufacturing method for the photodetector described above is merely one example, and other manufacturing methods may be adopted.

[0103] [Actions and Effects] The photodetector of this embodiment includes a splitter (splitter 20) provided on a substrate (substrate 101) and capable of transmitting an optical signal based on the output light of a light source (light source 10) and a reference signal, a scanner (scanner 30) provided on the substrate and capable of outputting the optical signal transmitted from the splitter, and a photodetector circuit (photodetector circuit 40) provided on the substrate and capable of receiving the optical signal reflected by an object and the reference signal.

[0104] The photodetector (photodetector 1) according to this embodiment includes a splitter 20 capable of transmitting an optical signal S1 and a reference signal S2 based on the output light of a light source 10, a scanner 30 capable of outputting the optical signal S1 transmitted from the splitter 20, and a photodetector circuit 40 capable of receiving an optical signal S3, which is reflected light, and the reference signal S2. The splitter 20, the scanner 30, and the photodetector circuit 40 are each provided on a substrate 101. This makes it possible to realize a photodetector with excellent performance.

[0105] Next, a modified example of the present disclosure will be described. In the following, the same components as those in the above embodiment will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0106] <2. Modifications> (2-1. Variation 1) In the above-described embodiment, an example configuration of the photodetector 1 has been described, but this is merely an example, and the configuration of the photodetector 1 is not limited to the above-described example. Fig. 16 is a diagram showing an example configuration of a photodetector according to Modification 1 of the present disclosure. For example, the photodetector 1 may include an attenuator 16. The attenuator 16 is an optical attenuator configured to be able to attenuate the reference signal S2.

[0107] The optical circuit 50 has, for example, a variable optical attenuator (VOA) as the attenuator 16. The attenuator 16 is provided, for example, between the splitter 20 and the mixer 41. In this modification, the provision of the attenuator 16 makes it possible to adjust the signal strength of the reference signal S2 in accordance with the signal strength (power) of the optical signal S3, which is the return light.

[0108] (2-2. Variation 2) 17 is a diagram showing an example of the configuration of a photodetector according to Modification 2. The photodetector 1 may have a measuring instrument 14. The measuring instrument 14 is configured to be able to measure the state of the output light of the light source 10. In the example shown in FIG. 17, the photodetector 1 has a splitter 13. In the photodetector 1, the splitter 13 transmits a portion of the output light of the light source 10 to the measuring instrument 14.

[0109] The measuring instrument 14 is configured to be able to measure the state of the output light of the light source 10 (for example, the intensity, wavelength, phase, etc. of the light) based on the output light (optical signal) of the light source 10 input via the splitter 13. The measuring instrument 14 is configured to include, for example, at least one of an interferometer and a resonator, and a photodetector.

[0110] The measuring instrument 14 is configured to monitor the output light of the light source 10 and determine the state of the output light of the light source 10. The measuring instrument 14 may be configured, for example, as an element (monitoring element) that monitors the oscillation state of the laser light from the light source 10. The measuring instrument 14 may also be called a determining unit (determination circuit) configured to be able to determine the state of the output light of the light source 10. The measuring instrument 14 may, for example, generate a signal related to the state of the output light of the light source 10 and output it to the signal processing circuit 70.

[0111] The signal processing circuit 70 can control the light source 10 and the generation and processing of interference signals by the light receiving circuit 40 based on the output signal of the measuring instrument 14. Furthermore, for example, the signal processing circuit 70 is configured to change the signal processing executed in the signal processing circuit 70 according to the output signal of the measuring instrument 14. By performing such feedback control, it is possible to improve the measurement accuracy of the photodetector 1.

[0112] (2-3. Variation 3) 18 is a diagram showing an example of the configuration of a photodetector according to Modification 3. The photodetector 1 may have a polarizer 17. The polarizer 17 is provided, for example, in an optical circuit 50, between the light source 10 and the splitter 20. By providing the polarizer 17, it becomes possible to remove unnecessary polarized components from the output light of the optical circuit 50 and reduce noise.

[0113] The optical detection device 1 may also include a measuring instrument 18 capable of measuring the ambient temperature. The measuring instrument 18 is a temperature detection element configured to be able to detect the temperature of the circuit. As an example, the measuring instrument 18 is provided around each circuit or element of the optical circuit 50. The measuring instrument 18 may generate a signal related to the temperature (e.g., a signal related to the temperature of an element of the optical circuit 50) and output it to, for example, the signal processing circuit 70.

[0114] The signal processing circuit 70 can control each circuit of the optical circuit 50 (such as the splitter 20, the switch unit 31 and antenna 32 of the scanner 30, the light receiving circuit 40, and the attenuator 16) based on the output signal of the measuring instrument 18. In the photodetector 1 according to this modification, stable operation can be achieved by monitoring the temperature and performing feedback control.

[0115] (2-4. Variation 4) 19 is a diagram showing a configuration example of a photodetector according to Modification 4. The photodetector 1 may have an isolator 19. The isolator 19 is provided, for example, in an optical circuit 50, between the light source 10 and the splitter 20. In this modification, the provision of the isolator 19 makes it possible to prevent degradation of the S / N ratio caused by light returning to the light source 10.

[0116] (2-5. Variation 5) Fig. 20 is a diagram showing a configuration example of a photodetector according to Modification 5. The photodetector 1 may be provided with a circulator 25. The circulator 25 has, for example, three ports (port 26a, port 26b, and port 26c) and is configured to transmit optical signals between the ports. In the example shown in Fig. 20, the ports 26a, 26b, and 26c are optically connected to the splitter 20, the scanner 30, and the mixer 41, respectively.

[0117] An optical signal S1, which is, for example, a frequency-modulated laser beam, is input to port 26a of circulator 25 from splitter 20. Circulator 25 can output optical signal S1 input to port 26a from port 26b to scanner 30. An optical signal S3, which is received light (reflected light), is input to port 26b of circulator 25 from scanner 30.

[0118] The circulator 25 can output the optical signal S3 input to the port 26b from the port 26c to the mixer 41. In this modification, the provision of the circulator 25 makes it possible to send the optical signal S3, which is the received light, to the mixer 41 without loss, thereby improving the S / N ratio of the optical signal (or interference signal).

[0119] (2-6. Variation 6) 21 and 22 are diagrams showing a configuration example of a photodetector according to Modification 6. As in the example shown in Fig. 21, the photodetector 1 may have a mark 96 that can be used for alignment. The mark 96 may be made of a metal material or another material.

[0120] The mark 96 is an alignment mark and is provided, for example, on the wiring layer 90. In the example shown in Fig. 21, the mark 96 is formed on the wiring layer 90 around the lens 36 serving as the light-collecting element 35. Note that the shape, arrangement, etc. of the mark 96 can be changed as appropriate.

[0121] 22, the light-detecting device 1 is provided with a countersunk portion 97. The countersunk portion 97 is, for example, a dug portion (groove portion) and is formed in the wiring layer 90. The spacer layer 95 and the light-collecting element 35 are arranged so as to be located in the countersunk portion 97, as in the example shown in FIG.

[0122] In the light-detecting device 1 according to this modification, the light-collecting element 35 (for example, the lens 36) can be aligned and disposed by providing at least one of the mark 96 and the countersunk portion 97. This makes it possible to suppress deterioration in characteristics due to misalignment of the light-collecting element 35 (lens 36).

[0123] (2-7. Variation 7) 23 and 24 are diagrams showing an example of the configuration of a photodetector according to Modification 7. FIG. 23 shows an example of the cross-sectional configuration of the photodetector, and FIG. 24 shows an example of the planar configuration of a scanner of the photodetector. The photodetector 1 may have a light-shielding member 80, as in the example shown in FIGS. 23 and 24. The light-shielding member 80 is a light-shielding portion (light-shielding film) made of a member that blocks light.

[0124] The light-shielding member 80 (light-shielding portion) is provided around at least one of the antenna 32 and the light-receiving element 46. For example, as in the examples shown in Fig. 23 or 24, the light-shielding member 80 is provided around the antenna 32 and prevents unnecessary light from entering the antenna 32. The scanner 30 may be configured to include the light-shielding member 80.

[0125] The light-shielding member 80 is provided, for example, next to the antenna 32 on the substrate 101. As an example, the light-shielding member 80 is provided for each antenna 32, and also provided between adjacent antennas 32. Furthermore, the light-shielding member 80 can be disposed between the antenna 32 and the light-receiving unit 45 (or the light-receiving element 46), as in the example shown in FIG.

[0126] The light-shielding member 80 is provided, for example, from below the spacer layer 95 to reach the surface 11S2 of the semiconductor layer 110. The light-shielding member 80 may be formed to extend in the thickness direction perpendicular to the surface 11S1 (or surface 11S2) of the semiconductor layer 110, i.e., in the Z-axis direction, and to reach the semiconductor layer 120. The light-shielding member 80 may be provided to penetrate the semiconductor layer 110.

[0127] 23, the light-shielding member 80 is formed around the antenna 32, penetrating the semiconductor layer 110 and the insulating layer 105 and reaching the semiconductor layer 120. As an example, the light-shielding member 80 is configured using a through via. A predetermined potential (voltage), for example, a GND potential (ground potential), is applied to the light-shielding member 80 via the wiring and vias of the wiring layer 90.

[0128] The light-shielding member 80 may be provided so as to surround the antenna 32 in a plan view. A light-shielding member 80 is provided for each antenna 32. For example, as in the example shown in Fig. 24 , the light-shielding member 80 may be formed so as to partially surround the antenna 32 in a plan view (i.e., when viewed on the XY plane).

[0129] The light-shielding member 80 is made of, for example, tungsten (W). The light-shielding member 80 may be made of other metal materials that block light, such as aluminum (Al) or copper (Cu). The light-shielding member 80 may also be made of a metal compound.

[0130] The light-shielding member 80 may be made of a material having a refractive index lower than that of the surrounding members, and may include a cavity (void). The light-shielding member 80 may also be made of a material that absorbs light. The light-shielding member 80 can also be considered a light-shielding wall that blocks incident light.

[0131] In the photodetector 1 according to this modification, the light-shielding member 80 is provided around the antenna 32, around the light-receiving element 46, etc., so that it is possible to prevent unwanted light (e.g., stray light) from entering the antenna 32, the light-receiving element 46, etc. For example, it is possible to prevent ranging errors caused by the mixing of stray light components having a frequency different from the frequency of the optical signal. It is possible to improve measurement accuracy.

[0132] (2-8. Variation 8) 25 and 26 are diagrams showing an example of the configuration of a photodetector according to Modification 8. FIG. 25 shows an example of a cross-sectional configuration of the photodetector, and FIG. 26 shows an example of a planar configuration of the photodetector. The photodetector 1 may have a mirror 34, as in the example shown in FIGS. 25 and 26. The photodetector 1 may also have a housing member 150.

[0133] The scanner 30 of the photodetector 1 may be configured to include, for example, the above-described switch unit 31, a mirror 34, and a light-collecting element 35. The mirror 34 is provided to reflect the optical signal (laser light) from the splitter 20. The mirror 34 is disposed, for example, so as to be located on the side surface of the semiconductor layer 110 in which the waveguide 15 is formed.

[0134] As shown schematically by the dotted line in Fig. 25, the optical signal S1 is incident on the mirror 34 via the waveguide 15 of the scanner 30 (the switch unit 31 thereof). The mirror 34 reflects the optical signal S1 toward the condensing element 35 (for example, the lens 36). The scanner 30 can emit the optical signal S1, which becomes, for example, frequency-modulated laser light, as transmission light to the measurement target by the mirror 34, the condensing element 35, etc.

[0135] The substrate 101 of the light detecting device 1 is provided in a package including, for example, a housing member 150. The package (housing member 150) is made of, for example, a ceramic material, a resin material, or the like. As in the example shown in FIG. 25 , a layer (lens array) including a plurality of lenses 36 is provided so as to be placed on, for example, the housing member 150. Note that, as the light collecting element 35, another light collecting element such as a metalens may be disposed.

[0136] The photodetector 1 may be configured such that a straight line L3 passing through the mirror 34 is misaligned with the optical axis of the light-collecting element 35. The straight line L3 is, for example, a vertical line passing through an intersection P between an extension of the waveguide 15 in the X-axis direction (or Y-axis direction) and the mirror surface. The straight line L3 may be a perpendicular line passing through the arrival point (i.e., the incident point) of the light on the mirror 34. The photodetector 1 may be configured such that the optical axis L1 of the lens 36 is inclined with respect to the straight line L3, as in the example shown in FIG. 25 . The lens 36 is disposed at an angle so that oblique light from the mirror 34 passes through the center of the lens 36.

[0137] By configuring the photodetector 1 as described above, it is possible to efficiently collect oblique light from the mirror 34. By making the transmitted light incident obliquely on the skin of the measurement target, it is possible to reduce noise caused by reflected light and improve measurement accuracy. For example, it is possible to accurately sense blood components.

[0138] The multiple waveguides 15 and mirrors 34 of the photodetector 1 may be provided on some or all of the sides of the substrate 101. For example, as in the example schematically shown in Fig. 26, the multiple waveguides 15 and multiple mirrors 34 may be arranged along the four sides of the substrate 101. By configuring the photodetector 1 in this manner, for example, the number of measurement points (i.e., areas where optical signals are transmitted and received) can be increased, and measurement accuracy can be improved.

[0139] The lens 36 may be provided so that the optical axis L1 of the lens 36 is shifted in the X-axis direction (or the Y-axis direction) with respect to the line L3. By configuring the photodetector 1 in this manner, the oblique light from the mirror 34 is corrected by the lens 36 so that it travels in the vertical direction (the Z-axis direction), and the transmitted light can be efficiently guided to the measurement target.

[0140] As with the example shown in Fig. 11, it is possible to realize a device that can accommodate a short working distance. In addition, it is possible to make the transmitted light perpendicular to the skin of the measurement target, thereby enabling sensing to be performed in deep regions. In this modified example, the same effects as those of the above-mentioned embodiment can be obtained.

[0141] <3. Usage example> The above-described photodetector device can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-rays, for example, as follows. ·Digital cameras, mobile devices with camera functions, and other devices that take images for viewing purposes - Devices used for traffic purposes, such as in-vehicle sensors that take pictures of the front, rear, surroundings, and interior of a vehicle for safe driving such as automatic stopping, and for recognizing the driver's condition, surveillance cameras that monitor moving vehicles and roads, and distance measuring sensors that measure distances between vehicles. A device used in home appliances such as televisions, refrigerators, and air conditioners to capture user gestures and operate the appliances according to those gestures. -Medical and healthcare equipment, such as endoscopes and devices that take blood vessel images using infrared light - Security devices such as surveillance cameras for crime prevention and cameras for person authentication Cosmetic devices such as skin measuring devices that take pictures of the skin and microscopes that take pictures of the scalp Sports equipment such as action cameras and wearable cameras for sports purposes Agricultural equipment such as cameras for monitoring the condition of fields and crops

[0142] <4. Application Examples> (Application example to endoscopic surgery system) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0143] FIG. 27 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0144] 27 shows an operator (doctor) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical instruments 11110 such as an insufflation tube 11111 and an energy treatment instrument 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0145] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the example shown, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0146] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens towards an object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0147] An optical system and an image sensor are provided inside the camera head 11102, and light reflected from the object of observation (observation light) is collected onto the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The image signal is sent to a camera control unit (CCU) 11201 as RAW data.

[0148] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102, and performs various image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0149] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0150] The light source device 11203 is configured from a light source such as an LED (Light Emitting Diode), and supplies irradiation light to the endoscope 11100 when photographing an operation site or the like.

[0151] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiating light, magnification, focal length, etc.) of the endoscope 11100.

[0152] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 inflates the body cavity of the patient 11132 through the insufflation tube 11111 in order to ensure a clear field of view for the endoscope 11100 and a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

[0153] The light source device 11203 that supplies illumination light to the endoscope 11100 when photographing the surgical site can be configured from a white light source configured from, for example, an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, making it possible to adjust the white balance of the captured image in the light source device 11203. In this case, it is also possible to capture images corresponding to each RGB in a time-division manner by irradiating the object of observation with laser light from each RGB laser light source in a time-division manner and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0154] Furthermore, the light source device 11203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free of so-called blocked-up shadows and blown-out highlights.

[0155] The light source device 11203 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light with a narrower band than the light irradiated during normal observation (i.e., white light), thereby capturing high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, known as narrow-band imaging. Alternatively, special light observation may be performed using fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light. Fluorescence observation can involve irradiating excitation light onto body tissues and observing the fluorescence from the tissues (autofluorescence observation), or locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow-band light and / or excitation light corresponding to such special light observation.

[0156] FIG. 28 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0157] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so that they can communicate with each other.

[0158] The lens unit 11401 is an optical system provided at the connection point with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses including a zoom lens and a focus lens.

[0159] The imaging unit 11402 is configured with an imaging element. The imaging element constituting the imaging unit 11402 may be one (a so-called single-chip type) or multiple (a so-called multi-chip type). When the imaging unit 11402 is configured with a multi-chip type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining these signals. Alternatively, the imaging unit 11402 may be configured with a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (dimensional) display. 3D display enables the surgeon 11131 to more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 11402 is configured with a multi-chip type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0160] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately after the objective lens.

[0161] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted appropriately.

[0162] The communication unit 11404 is configured by a communication device for transmitting and receiving various types of information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0163] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of imaging, and / or information specifying the magnification and focus of the captured image.

[0164] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0165] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404 .

[0166] The communication unit 11411 is configured by a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0167] Furthermore, the communication unit 11411 transmits to the camera head 11102 a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0168] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data sent from the camera head 11102 .

[0169] The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0170] Furthermore, the control unit 11413 causes the display device 11202 to display a captured image showing the surgical site, etc., based on the image signal that has been image processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0171] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for communication of electrical signals, an optical fiber for optical communication, or a composite cable of these.

[0172] In the illustrated example, communication is performed by wire using the transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0173] The foregoing has described an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied. Of the configurations described above, the technology according to the present disclosure can be suitably applied to, for example, the imaging unit 11402 provided in the camera head 11102 of the endoscope 11100. By applying the technology according to the present disclosure to the imaging unit 11402, it is possible to provide a high-definition endoscope 11100. The technology according to the present disclosure makes it possible to arrange a miniaturized OCT device at the tip of the lens barrel, which is expected to lead to the realization of a higher-definition endoscope.

[0174] Although the present disclosure has been described above by giving embodiments, modifications, use examples, and application examples, the present technology is not limited to the above-described embodiments, etc., and various modifications are possible. For example, although the modifications described above have been described as modifications of the above-described embodiments, the configurations of the modifications can be combined as appropriate.

[0175] According to an embodiment of the present disclosure, a photodetector includes a splitter provided on a substrate and capable of transmitting an optical signal based on output light from a light source and a reference signal, a scanner provided on the substrate and capable of outputting the optical signal transmitted from the splitter, and a light receiving circuit provided on the substrate and capable of receiving the optical signal reflected by an object and the reference signal. This makes it possible to realize a photodetector with good performance.

[0176] The effects described in this specification are merely examples and are not limited to those described, and other effects may also be achieved. Furthermore, the present disclosure may also be configured as follows. (1) a splitter provided on the substrate and capable of transmitting an optical signal based on output light from the light source and a reference signal; a scanner provided on the substrate and capable of outputting the optical signal transmitted from the splitter; a light receiving circuit provided on the substrate and capable of receiving the optical signal reflected by an object and the reference signal; A light detection device comprising: (2) The light receiving circuit includes: a mixer capable of mixing the optical signal reflected by the object with the reference signal; a light receiving element capable of receiving the mixed optical signal; have The photodetector according to (1) above. (3) The light source is capable of generating frequency-modulated output light. The photodetector according to (1) or (2) above. (4) The optical fiber further includes at least one of a variable optical attenuator capable of attenuating the reference signal and an isolator provided between the light source and the splitter. The photodetector according to any one of (1) to (3) above. (5) a circulator provided between the scanner and the light receiving circuit; the scanner is capable of outputting the optical signal that is frequency modulated and receiving the optical signal reflected from the object; The circulator is capable of transmitting the optical signal received by the scanner to the light receiving circuit. The photodetector according to any one of (1) to (4) above. (6) a first measuring device capable of measuring the ambient temperature; a second measuring instrument capable of measuring the state of the output light of the light source; a polarizer disposed between the light source and the splitter; Further comprising at least one of The photodetector according to any one of (1) to (5) above. (7) a first light source capable of generating output light in a first wavelength band; a second light source capable of generating output light in a second wavelength band; an optical circuit including the splitter, the scanner, and the light receiving circuit; Equipped with The optical circuit is provided for the first light source and the second light source as the light source. The photodetector according to any one of (1) to (6) above. (8) a waveguide element capable of transmitting at least one of the output light of the first light source and the output light of the second light source to the splitter; The photodetector according to (7) above. (9) a first light source capable of generating output light in a first wavelength band; a second light source capable of generating output light in a second wavelength band; a first optical circuit and a second optical circuit, each including the splitter, the scanner, and the light receiving circuit; Equipped with the first optical circuit is provided for the first light source as the light source, The second optical circuit is provided for the second light source as the light source. The photodetector according to any one of (1) to (8) above. (10) The scanner has a plurality of antennas capable of outputting the optical signals. The photodetector according to any one of (1) to (9) above. (11) The antenna further includes a light blocking member provided between adjacent antennas. The photodetector according to (10) above. (12) The scanner a first antenna capable of outputting the optical signal in a first wavelength band; a second antenna that is provided adjacent to the first antenna and is capable of outputting the optical signal in a second wavelength band; Contains The photodetector according to any one of (1) to (11) above. (13) the scanner has a plurality of the first antennas; The second antenna is provided between adjacent ones of the first antennas. The photodetector according to (12) above. (14) the scanner has a plurality of the first antennas and a plurality of the second antennas; The first antenna and the second antenna are arranged in a checkerboard pattern. The photodetector according to (12) or (13) above. (15) The scanner has a mirror that reflects the optical signal from the splitter. The photodetector according to any one of (1) to (14) above. (16) The scanner a plurality of antennas capable of outputting the optical signals; a light-collecting element provided for each of the antennas; have The photodetector according to any one of (1) to (15) above. (17) The line passing through the center of the antenna is misaligned with the optical axis of the light-collecting element. The photodetector according to (16) above. (18) The focusing element is a lens that focuses the optical signal from the antenna. The photodetector according to (16) or (17) above. (19) The substrate further includes an alignment mark provided around the light-collecting element. The photodetector according to any one of (16) to (18) above. (20) The light detection device is an OCT device. The photodetector according to any one of (1) to (19) above. [Explanation of symbols]

[0177] 1...photodetector, 10...light source, 20...splitter, 30...scanner, 31...switch section, 32...antenna, 40...photodetector circuit, 41...mixer, 45...photodetector section, 46...photodetector element, 60...amplifier circuit, 70...signal processing circuit

Claims

1. a splitter provided on the substrate and capable of transmitting an optical signal based on output light from the light source and a reference signal; a scanner provided on the substrate and capable of outputting the optical signal transmitted from the splitter; a light receiving circuit provided on the substrate and capable of receiving the optical signal reflected by an object and the reference signal; A light detection device comprising:

2. The light receiving circuit includes: a mixer capable of mixing the optical signal reflected by the object with the reference signal; a light receiving element capable of receiving the mixed optical signal; have The photodetector device according to claim 1 .

3. The light source is capable of generating frequency-modulated output light. The photodetector device according to claim 1 .

4. The optical fiber further includes at least one of a variable optical attenuator capable of attenuating the reference signal and an isolator provided between the light source and the splitter. The photodetector device according to claim 1 .

5. a circulator provided between the scanner and the light receiving circuit; the scanner is capable of outputting the optical signal that is frequency modulated and receiving the optical signal reflected from the object; The circulator is capable of transmitting the optical signal received by the scanner to the light receiving circuit. The photodetector device according to claim 1 .

6. a first measuring device capable of measuring an ambient temperature; a second measuring device capable of measuring the state of the output light of the light source; a polarizer disposed between the light source and the splitter; Further comprising at least one of The photodetector device according to claim 1 .

7. a first light source capable of generating output light in a first wavelength band; a second light source capable of generating output light in a second wavelength band; an optical circuit including the splitter, the scanner, and the light receiving circuit; Equipped with The optical circuit is provided for the first light source and the second light source as the light source. The photodetector device according to claim 1 .

8. The light source further includes a waveguide element capable of transmitting at least one of the output light of the first light source and the output light of the second light source to the splitter. The photodetector device according to claim 7 .

9. a first light source capable of generating output light in a first wavelength band; a second light source capable of generating output light in a second wavelength band; a first optical circuit and a second optical circuit each including the splitter, the scanner, and the light receiving circuit; Equipped with the first optical circuit is provided for the first light source serving as the light source, The second optical circuit is provided for the second light source as the light source. The photodetector device according to claim 1 .

10. The scanner has a plurality of antennas capable of outputting the optical signals. The photodetector device according to claim 1 .

11. The antenna further includes a light blocking member provided between adjacent antennas. The optical detection device according to claim 10.

12. The scanner a first antenna capable of outputting the optical signal in a first wavelength band; a second antenna that is provided adjacent to the first antenna and is capable of outputting the optical signal in a second wavelength band; Contains The photodetector device according to claim 1 .

13. the scanner has a plurality of the first antennas; The second antenna is provided between adjacent ones of the first antennas. The optical detection device according to claim 12.

14. the scanner has a plurality of the first antennas and a plurality of the second antennas; The first antenna and the second antenna are arranged in a checkerboard pattern. The optical detection device according to claim 12.

15. The scanner has a mirror that reflects the optical signal from the splitter. The photodetector device according to claim 1 .

16. The scanner a plurality of antennas capable of outputting the optical signals; a light-collecting element provided for each of the antennas; have The photodetector device according to claim 1 .

17. The line passing through the center of the antenna is misaligned with the optical axis of the light-collecting element.

17. The optical detection device of claim 16.

18. The focusing element is a lens that focuses the optical signal from the antenna.

17. The optical detection device of claim 16.

19. The substrate further includes an alignment mark provided around the light-collecting element.

17. The optical detection device of claim 16.

20. The light detection device is an OCT device. The photodetector device according to claim 1 .

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