WO2025249388A1

WO2025249388A1 - Photodetector

Info

Publication number: WO2025249388A1
Application number: PCT/JP2025/018980
Authority: WO
Inventors: Yoshihiro Ando; Shinpei OGINO; Taichiro FUKUI; Haruhiko Terada; Hiroshi Yoshida
Original assignee: Sony Semiconductor Solutions Corp
Current assignee: Sony Semiconductor Solutions Corp
Priority date: 2024-05-28
Filing date: 2025-05-26
Publication date: 2025-12-04
Anticipated expiration: 2026-11-28
Also published as: JP2025179532A

Abstract

An optical device includes a first light source (10), a multilayer structure (101), a waveguide disposed in the multilayer structure (101) and configured to receive light from the first light source (10), and a first antenna structure (30) comprising a first antenna (32) disposed in the multilayer structure (101) and optically coupled to the waveguide (15), and a lens structure (35) on the multilayer structure (101) and comprising a lens (36) overlapped with the first antenna (32) in a plan view. In a cross-sectional view, a center line of the first antenna (32) passes through the lens (36), and the lens (36) has at least one focal point that is offset from the center line of the first antenna structure (32) in a lateral direction.

Description

PHOTODETECTOR

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Priority Patent Application JP2024-086354 filed on May 28, 2024, the entire contents of each which are incorporated herein by reference.

The present disclosure relates to a photodetector.

An optical coherence tomography (OCT: Optical Coherence Tomography) system including a photonic integrated circuit (PIC: Photonic Integrated Circuit) has been proposed (PTL 1).

[PTL 1] US Patent Application Publication No. 2014/0376001

Summary

It is desirable to improve detection performance of a device that detects light.

It is desired to provide a photodetector having favorable performance.

A photodetector according to one embodiment of the present disclosure includes a splitter, a scanner, and a light reception circuit. The splitter is provided on a substrate and is configured to transmit an optical signal and a reference signal. The optical signal is based on output light of a light source. The scanner is provided on the substrate and is configured to output the optical signal transmitted from the splitter. The light reception circuit is provided on the substrate and is configured to receive the optical signal reflected by a target, and the reference signal.

Fig. 1 is a diagram illustrating an example of a schematic configuration of a photodetector according to an embodiment of the present disclosure. Fig. 2 is a diagram for describing an example of a signal generated by the photodetector according to the embodiment of the present disclosure. Fig. 3 is a diagram illustrating an example of a cross-sectional configuration of the photodetector according to the embodiment of the present disclosure. Fig. 4 is a diagram illustrating a configuration example of the photodetector according to the embodiment of the present disclosure. Fig. 5 is a diagram illustrating another configuration example of the photodetector according to the embodiment of the present disclosure. Fig. 6 is a diagram illustrating another configuration example of the photodetector according to the embodiment of the present disclosure. Fig. 7 is a diagram for describing an arrangement example of antennas of the photodetector according to the embodiment of the present disclosure. Fig. 8 is a diagram for describing an arrangement example of the antennas of the photodetector according to the embodiment of the present disclosure. Fig. 9 is a diagram for describing an arrangement example of the antennas of the photodetector according to the embodiment of the present disclosure. Fig. 10 is a diagram for describing an arrangement example of the antennas of the photodetector according to the embodiment of the present disclosure. Fig. 11 is a diagram for describing a configuration example of the photodetector according to the embodiment of the present disclosure. Fig. 12 is a diagram for describing a configuration example of the photodetector according to the embodiment of the present disclosure. Fig. 13 is a diagram for describing another configuration example of the photodetector according to the embodiment of the present disclosure. Fig. 14 is a diagram for describing another configuration example of the photodetector according to the embodiment of the present disclosure. Fig. 15A is a diagram illustrating an example of a manufacturing method of the photodetector according to the embodiment of the present disclosure. Fig. 15B is a diagram illustrating an example of the manufacturing method of the photodetector according to the embodiment of the present disclosure. Fig. 15C is a diagram illustrating an example of the manufacturing method of the photodetector according to the embodiment of the present disclosure. Fig. 15D is a diagram illustrating an example of the manufacturing method of the photodetector according to the embodiment of the present disclosure. Fig. 15E is a diagram illustrating an example of the manufacturing method of the photodetector according to the embodiment of the present disclosure. Fig. 15F is a diagram illustrating an example of the manufacturing method of the photodetector according to the embodiment of the present disclosure. Fig. 16 is a diagram illustrating a configuration example of a photodetector according to Modification example 1 of the present disclosure. Fig. 17 is a diagram illustrating a configuration example of a photodetector according to Modification example 2 of the present disclosure. Fig. 18 is a diagram illustrating a configuration example of a photodetector according to Modification example 3 of the present disclosure. Fig. 19 is a diagram illustrating a configuration example of a photodetector according to Modification example 4 of the present disclosure. Fig. 20 is a diagram illustrating a configuration example of a photodetector according to Modification example 5 of the present disclosure. Fig. 21 is a diagram illustrating a configuration example of a photodetector according to Modification example 6 of the present disclosure. Fig. 22 is a diagram illustrating a configuration example of the photodetector according to Modification example 6 of the present disclosure. Fig. 23 is a diagram illustrating a configuration example of a photodetector according to Modification example 7 of the present disclosure. Fig. 24 is a diagram illustrating a configuration example of the photodetector according to Modification example 7 of the present disclosure. Fig. 25 is a diagram illustrating a configuration example of a photodetector according to Modification example 8 of the present disclosure. Fig. 26 is a diagram illustrating a configuration example of the photodetector according to Modification example 8 of the present disclosure. Fig. 27 is a view depicting an example of a schematic configuration of an endoscopic surgery system. Fig. 28 is a block diagram depicting an example of a functional configuration of a camera head and a camera control unit (CCU).

Description of Embodiment

Some embodiments of the present disclosure will be described below in detail with reference to the drawings. Note that the description will be given in the following order.
1. Embodiment
2. Modification Examples
3. Use Examples
4. Application Examples
<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. A photodetector 1 is a device configured to detect incident light. The photodetector 1 (also referred to as an optical device in an optical system) may be configured as a device configured to perform ranging, i.e., as a ranging device. The photodetector 1 (the ranging device) may perform, for example, distance measurement or generation of a tomographic image, with use of interference of light.

The photodetector 1 is configured to, for example, measure a heart rate, a blood flow, a blood component, and the like as biomarkers by an OCT (Optical Coherence Tomography) technique. The photodetector 1 may be configured as a blood component sensor. Examples of the blood component include glucose, lactic acid, a neutral fat, and a fatty acid. The photodetector 1 acquires a signal (information) related to a state of a living body. This makes it possible to check the state of the living body.

The photodetector 1 is applied to an OCT device, for example. The photodetector 1 is applied as an optical coherence tomograph, and may also be referred to as an optical coherence tomography imaging apparatus (or an optical coherence tomography image shooting apparatus). The photodetector 1 is usable in, for example, an electronic apparatus to be worn and used by a user. The photodetector 1 may be applied to an apparatus wearable on a body part such as a hand, a wrist, an arm, or a foot, and may be implemented as a device to be mounted on a wearable device.

The photodetector 1 may transmit and receive an optical signal to be modulated light having a modulated frequency, and may measure a distance to a target, an image of the target, etc. The photodetector 1 includes, for example, a photonic integrated circuit (PIC: Photonic Integrated Circuit). The photodetector 1 may include a substrate (a silicon substrate, an SOI (Silicon On Insulator) substrate, or the like) including silicon and may be manufactured by a silicon photonics technology. The photodetector 1 has, for example, a structure (a stacked structure) configured by stacking a plurality of substrates.

As illustrated in Fig. 1, the photodetector 1 includes, for example, a light source 10, an optical circuit 50, an amplifier circuit 60, and a signal processing circuit 70. The optical circuit 50 includes a scanner 30, a light reception circuit 40, etc. The photodetector 1 may irradiate a target (e.g., skin) with a frequency-modulated optical signal by the light source 10, the scanner 30, etc., and may receive the optical signal reflected by the target. For example, the photodetector 1 irradiates the skin as a measurement target with an optical signal (laser light), and receives the optical signal reflected by a layer in the skin and delayed.

In the photodetector 1, for example, reference light branched (split) from output light of the light source 10 and reflected light (feedback light) reflected by the measurement target are caused to incident on (inputted to) the light reception circuit 40, and an electric signal having a frequency based on a frequency of the reference light and a frequency of the reflected light is detected. The electric signal generated by receiving the reflected light from the measurement target is, for example, a beat signal having a frequency based on a difference between the frequency of the reference light and the frequency of the reflected light, and is a signal based on a distance to the measurement target.

The optical circuit 50, the amplifier circuit 60, the signal processing circuit 70, etc. may be provided on one substrate (for example, 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 in a plurality of layers. The photodetector 1 may have a stacked structure in which a plurality of substrates is stacked.

The light source 10 is provided, for example, together with the scanner 30, the light reception circuit 40, etc. on the same substrate, and is mounted on the photodetector 1. Note that the light source 10 may be provided outside the photodetector 1. The photodetector (the photodetector 1) may be configured as a light detection system including the light source 10, the optical circuit 50, the amplifier circuit 60, the signal processing circuit 70, etc.

The light source 10 is configured to generate an optical signal. The light source 10 includes, for example, a light emitting element, and is configured to output the optical signal (laser light). The light source 10 includes, for example, a variable laser light source, and outputs the output light that is to be the frequency-modulated optical signal to the measurement target via the optical circuit 50. For example, the light source 10 includes a III-V compound semiconductor material (InP, GaAs, or the like), and has a configuration in which a p-type cladding layer, an active layer, and an n-type cladding layer are stacked.

The light source 10 may generate frequency-modulated laser light, and may emit the frequency-modulated laser light. That is, the light source 10 may generate and output a signal (a chirp signal) having a frequency that varies continuously over time. Note that the light source 10 may include a semiconductor optical amplifier (SOA: Semiconductor Optical Amplifier).

The optical circuit 50 includes, for example, the splitter 20 (also referred to as an optical splitter), the scanner 30, and the light reception circuit 40. The output light (e.g., the frequency-modulated laser light) of the light source 10 is inputted to (caused to be incident on) the splitter 20. For example, the output light of the light source 10 is branched (split) 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.

In the example illustrated in Fig. 1, an optical signal S1 that is a portion of the output light of the light source 10 is transmitted by the splitter 20 to the scanner 30 side. In addition, an optical signal (which will be referred to as a "reference signal S2") that is another portion of the output light of the light source 10 is transmitted to the light reception circuit 40 side. For example, the reference signal S2 having power (quantity of light) of 50% or less of power of the output light of the light source 10 is divided from the output light of the light source 10 as the reference light (local light), and is inputted to (caused to be incident on) the light reception circuit 40.

The scanner 30 is configured to output (transmit) the optical signal. For example, the scanner 30 is configured to output, to an outside, the optical signal transmitted from the light source 10 via the splitter 20. In the example illustrated in Fig. 1, the frequency-modulated optical signal S1 is propagated from the splitter 20 to the scanner 30. The scanner 30 may emit the optical signal S1, which is the frequency-modulated laser light, as output light (i.e., transmitted light or irradiation light) to the measurement target.

Further, the scanner 30 is configured to receive the optical signal (receive light) reflected by the measurement target. The scanner 30 may receive, for example, an optical signal S3, which is the laser light reflected by the measurement target and delayed. The scanner 30 outputs the optical signal S3, which is reflected light (i.e., the received light), to the light reception circuit 40 via the splitter 20.

The scanner 30 includes, for example, a plurality of switch units 31 (also referred to as optical switches) and an antenna 32. The antenna 32 is configured to output an optical signal. In addition, the antenna 32 is configured to receive the optical signal reflected by the measurement target. The antenna 32 is a transmission antenna configured to transmit an optical signal, and is also a reception antenna configured to receive an optical signal.

The antenna 32 includes a diffraction grating, for example. For example, the antenna 32 includes Si (silicon), and is configured as a transmission/reception antenna. The antenna 32 may irradiate the measurement target with frequency-modulated laser light, and may receive the laser light reflected by the measurement target and delayed.

The switch unit 31 includes a plurality of switches (optical switches) corresponding to a plurality of antennas 32, and is configured to select the antenna 32 that is to be a transmission destination of the optical signal S1 from the splitter 20. Switching a transmission path of the optical signal S1 by the switch unit 31 changes the antenna 32 that emits the optical signal S1, and thus changes an emission direction (a traveling direction) of the optical signal S1.

The light reception circuit 40 is configured receive the optical signal reflected by the target, and the reference light. The light reception circuit 40 includes, for example, a mixer 41 (also referred to as an optical mixer) and a light reception unit 45. The mixer 41 is configured to mix the optical signal reflected by the measurement target, and the reference signal. For example, the mixer 41 (a mixing device) is configured to mix (mix) the reference light and the reflected light, and output the mixed optical signal.

In the example illustrated in Fig. 1, the mixer 41 is configured to mix the reference signal S2, which is the reference light inputted from the light source 10 and the splitter 20, and the optical signal S3, which is the reflected light (i.e., the received light) inputted from the scanner 30 and the splitter 20. The mixer 41 may transmit the optical signal obtained by mixing the reference light and the reflected light to the light reception unit 45.

For example, the light reception circuit 40 is configured to cause interference between the reference light and the reflected light, and generate interfered light (interference light). The light reception circuit 40 may generate an optical signal in which the reference signal S2 and the optical signal S3, which is the reflected light, are combined (multiplexed), and may output the generated optical signal to the light reception unit 45.

The light reception circuit 40 includes the light reception unit 45 including a light reception element 46 (a light reception element 46a and a light reception element 46b in Fig. 1). For example, the light reception element 46 is a photodiode (PD), and is configured to receive an optical signal. The light reception circuit 40 is configured to receive an optical signal and convert the optical signal into an electric signal.

In the example illustrated in Fig. 1, the light reception unit 45 (also referred to as a light detector) includes the light reception element 46a and the light reception element 46b that are balanced photodiodes. The light reception element 46a and the light reception element 46b are electrically coupled to each other in series. Each of the light reception element 46a and the light reception element 46b is configured, for example, to receive the optical signal via the mixer 41.

The light reception element 46 (each of the light reception elements 46a and 46b in Fig. 1) may receive light, may generate electric charge by photoelectric conversion, and may output a current. The light reception element 46 is configured to output a signal based on the reference signal S2 and the optical signal S3 reflected by an object. For example, in response to reception of the optical signal in which the reference signal S2 and the optical signal S3 as the reflected light are mixed (mixed), a signal based on a photocurrent flowing through the light reception unit 45 is generated and outputted to the amplifier circuit 60.

For example, the amplifier circuit 60 is electrically coupled to the light reception unit 45, and is configured to output a signal based on the photocurrent generated by the light reception unit 45. The amplifier circuit 60 is provided for the light reception element 46a and the light reception element 46b, and is configured to output a signal S4 based on the photocurrent generated by the light reception element 46a and the light reception element 46b. For example, the amplifier circuit 60 includes a transimpedance amplifier (TIA: Transimpedance Amplifier), and is configured to convert a current signal into a voltage signal.

In the example illustrated in Fig. 1, the amplifier circuit 60 is electrically coupled to a node that couples the light reception element 46a and the light reception element 46b to each other. The amplifier circuit 60 may convert a current signal detected by the light reception unit 45 into a voltage signal, and may output the signal S4, which is the voltage signal, to the signal processing circuit 70. The signal S4 has, for example, a frequency corresponding to a frequency difference between the optical signal S1 (and the reference signal S2) and the optical signal S3. The signal S4 may also be referred to as an interference signal or a beat signal.

The amplifier circuit 60 may be referred to as a detection circuit configured to output an electric signal based on an optical signal. For example, the amplifier circuit 60 may include a TIA circuit as described above, and may output, to the signal processing circuit 70, the signal S4 to be the voltage signal based on the optical signal received by the light reception unit 45. Note that the amplifier circuit 60 and the light reception unit 45 may also be collectively referred to as a detection circuit.

Fig. 2 is a diagram for describing an example of signals generated by the photodetector according to the embodiment. In Fig. 2, a vertical axis represents a frequency f of an optical signal that is a chirp signal, and a horizontal axis represents time t. Fig. 2 illustrates the optical signal S1 that is transmitted light to the measurement target, and the optical signal S3 that is the received light from the measurement target.

In the light reception circuit 40, the mixer 41 outputs, to the light reception unit 45, the interference light generated by mixing an optical signal for reference corresponding to the transmitted optical signal S1, i.e., the reference signal S2, and the optical signal S3. In the light reception circuit 40, the light reception unit 45 receives the interference light from the mixer 41. The light reception circuit 40 may generate and output the signal S4. In the photodetector 1, it is possible to determine the distance to the measurement target, etc. with use of the signal S4.

The signal processing circuit 70 is configured to perform signal processing. The signal processing circuit 70 includes a circuit that performs various kinds of signal processing on a signal inputted from the amplifier circuit 60. The signal processing circuit 70 includes an arithmetic circuit, a memory circuit, etc. The signal processing circuit 70 (a signal processor) may include a processor and a memory.

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 perform AD (Analog Digital) conversion, and converts an inputted analog signal into a digital signal. The AD conversion circuit 71 is an ADC (Analog to Digital Converter). The AD conversion circuit 71 receives the signal S4, which is the interference signal (the beat signal) from, for example, the amplifier circuit 60.

The AD conversion circuit 71 performs an AD conversion process on the signal S4 which is an analog signal inputted from the amplifier circuit 60. For example, the AD conversion circuit 71 (the AD converter) may sample the signal S4, and may convert the signal S4, which is an analog signal, into a digital signal. The AD conversion circuit 71 outputs, to the arithmetic circuit 72, the signal S4, at each sampling point, converted into a digital signal.

The arithmetic circuit 72 is configured to acquire the signal S4 converted into the digital signal and perform an arithmetic process. The arithmetic circuit 72 (an arithmetic unit) includes, for example, a logic circuit, a memory, etc. The arithmetic circuit 72 is configured to perform a frequency analysis process on the signal S4. The arithmetic circuit 72 may also be referred to as an analyzer configured to analyze the signal S4.

For example, the arithmetic circuit 72 determines a distance to the measurement target, an image of the measurement target, etc. by performing FFT (Fast Fourier Transform; fast Fourier transform) on the signal S4. For example, the signal processing circuit 70 calculates the distance to the measurement target on the basis of a frequency (e.g., a beat frequency) of the signal S4 in a case where a frequency of the laser light is increased (or decreased) over time.

The signal processing circuit 70 may generate a signal related to the distance to the target, a signal related to the image of the target, etc., and may output the signals to the outside of the photodetector 1. In addition, the signal processing circuit 70 is also a controller (a control circuit), and is configured to control each unit of the photodetector 1. The signal processing circuit 70 may include a circuit such as a PLL (Phase Locked Loop), a DAC (Digital to Analog Converter), or the like.

For example, the signal processing circuit 70 is configured to supply, to the light source 10, a signal for controlling the light source 10, and to control the light source 10. In addition, for example, the signal processing circuit 70 is configured to control the scanning of the optical signal performed by the scanner 30, the generation process of the interference signal (the beat signal) performed by the light reception circuit 40, the AD conversion process performed by the AD conversion circuit 71, etc.

Fig. 3 is a diagram illustrating an example of a cross-sectional configuration of the photodetector according to the embodiment. The photodetector 1 includes a substrate 101 including silicon. The substrate 101 includes, for example, a semiconductor substrate such as an SOI (Silicon On Insulator) substrate or a silicon substrate. The substrate 101 may have or be referred to as a multilayer structure 101.

In the example illustrated in Fig. 3, the substrate 101 includes a layer 110, an insulating layer 105, a layer 120, and a wiring layer 90. The layers 110 and 120 are each, for example, a semiconductor layer. The layer 110 and the layer 120 are also referred to as a semiconductor layer 110 and a semiconductor layer 120, respectively. For example, the semiconductor layer 110 and the semiconductor layer 120 are each a silicon layer, and the insulating layer 105 is a BOX (Buried Oxide) layer.

Note that each of the layer 110 and the layer 120 may include another semiconductor material, or may include another material. For example, the layer 110 (or the layer 120) to be a waveguide may include a material (e.g., silicon nitride or the like) that has a refractive index higher than that of a surrounding material and transmits an optical signal (laser light) therethrough.

The photodetector 1 has, for example, a configuration in which the wiring layer 90, the semiconductor layer 110, the insulating layer 105, and the semiconductor layer 120 are stacked in a Z-axis direction. Note that as illustrated in Fig. 3, a direction orthogonal to the Z-axis direction is set to an X-axis direction, and a direction orthogonal to the Z-axis direction and the X-axis direction is set to a Y-axis direction. In the drawings described below, directions are sometimes described based on the arrowed directions in Fig. 3.

As illustrated in Fig. 3, the semiconductor layer 110 has a surface 11S1 and a surface 11S2 that are opposed to each other. The surface 11S2 is a surface on an opposite side to the surface 11S1. The insulating layer 105 is provided on the surface 11S2 side of the semiconductor layer 110. The wiring layer 90 is provided on the surface 11S1 side of the semiconductor layer 110. The optical circuit 50, the light reception circuit 40, etc. described above are provided in the semiconductor layer 110 and the wiring layer 90 of the substrate 101.

For example, the scanner 30 including the plurality of antennas 32, the light reception unit 45 including the light reception element 46 (the light reception element 46a and the light reception element 46b in Fig. 1), etc. are provided on the surface 11S1 side of the semiconductor layer 110. In other words, the optical circuit 50, the light reception unit 45, etc. are provided on the semiconductor layer 110. The scanner 30 may be referred to as an antenna structure 30 with individual antennas 32.

For example, the light reception element 46 includes a germanium photodiode (GePD), and is provided on the surface 11S1 of the semiconductor layer 110. Note that 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 may be provided in a semiconductor layer different from the semiconductor layer 110.

For example, the wiring layer 90 includes a conductor film and an insulating film, and includes a plurality of wirings, a plurality of vias, etc. The wiring layer 90 has, for example, a configuration in which the plurality of wirings is stacked with an insulating film serving as an interlayer insulating film interposed therebetween. The wiring layer 90 is a multilayer wiring layer, and includes, for example, two or more layers or three or more layers of wirings.

The wirings of the wiring layer 90 include, for example, a metal material such as aluminum (Al), tungsten (W), or copper (Cu). The wirings of the wiring layer 90 may include another conductive material such as polysilicon (Poly-Si). The interlayer insulating film includes, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), or the like.

The substrate 101 is provided with the scanner 30 including the plurality of antennas 32 and a heater 38. The antennas 32 are provided in the semiconductor layer 110, as in the example illustrated in Fig. 3, for example. The plurality of antennas 32 is provided along the surface 11S1 and the surface 11S2 of the semiconductor layer 110. In the substrate 101, the plurality of antennas 32 is disposed, for example, side by side in the X-axis direction and the Y-axis direction. The scanner 30 may include an antenna array including the plurality of antennas 32.

The antenna 32 includes, for example, a waveguide having a plurality of holes (openings) provided through the semiconductor layer 110, a waveguide having a plurality of grooves, or the like. The antenna 32 may include a diffraction grating provided in the waveguide. For example, the antenna 32 includes a diffraction grating including a periodically formed pattern (e.g., a circular hole pattern).

For example, the heater 38 is provided around the switch (i.e., the optical switch) of the switch unit 31 described above, and is configured to heat the switch of the switch unit 31. For example, the heater 38 includes a resistive element (a resistor), and is provided for each of the optical switches or for each unit of multiple optical switches. For example, the heater 38 (a heater unit) is electrically coupled to the vias, the wirings, etc. of the wiring layer 90 as schematically illustrated in Fig. 3, and is configured to be electrically continuous therewith.

In the scanner 30, it is possible to switch the antenna 32 to be the transmission destination of the optical signal S1 by applying heat to the optical switch through current supply to the heater 38, and to thereby change the refractive index of the waveguide of the optical switch. For example, the signal processing circuit 70 may change the antenna 32 (i.e., the diffraction grating) that emits the optical signal S1, by controlling the current supply to the heater 38.

In addition, for example, the heater 38 may be provided around the antenna 32, and may be configured to heat the antenna 32. The signal processing circuit 70 may change the refractive index of the antenna 32 through a temperature control of the heater 38, and may thereby finely adjust a direction of the optical signal S1 to be emitted from the antenna 32 (i.e., the diffraction grating). The heater 38 may be disposed for each of the antennas 32 or for each unit of a plurality of antennas 32.

In addition, the photodetector 1 is provided with the above-described light source 10 and a waveguide 15. For example, the light source 10 is so disposed on the substrate 101 as to be positioned on a side surface side of the semiconductor layer 110. In the example illustrated in Fig. 3, the light source 10 is provided above the semiconductor layer 120 so that the output light (the optical signal) of the light source 10 is to be incident on the waveguide 15. In addition, for example, the light source 10 is electrically coupled to a circuit, which controls the light source 10, by an electrode 91 and an electrode 92.

For example, the waveguide 15 is a Si (silicon) waveguide, and is provided in the semiconductor layer 110. The waveguide 15 is configured to guide an inputted (incident) optical signal. Note that the waveguide 15 may include another semiconductor material, or may include another material (e.g., silicon nitride). The waveguide 15 may include another material having a refractive index higher than that of a surrounding member (e.g., the insulating film of the wiring layer 90, or the insulating layer 105).

The waveguide 15 may be provided between the light source 10 and the splitter 20, between the splitter 20 and the scanner 30, between the splitter 20 and the light reception circuit 40, etc. In the example illustrated in Fig. 3, the waveguide 15 is configured to transmit the optical signal (cause the optical signal to propagate) from the light source 10 side to the scanner 30 side, for example.

The scanner 30 of the photodetector 1 includes a light collecting element 35, as in the example illustrated in Fig. 3. For example, the light collecting element 35 includes a lens 36, and is provided above the antenna 32. The light collecting element 35 may be referred to as a lens structure 35 with individual lenses 36. The light collecting element 35 is an optical member that collects light (the transmitted light) from the antenna 32, and may also be referred to as a light guiding element. In addition, the light collecting element 35 guides the reflected light (the feedback light) from the measurement target to the antenna 32 side. As discussed herein and with reference to for example, Figs. 11, 13, and 14, a lens 36 may have at least one focal point that is offset from a center line of the antenna structure 30 in a lateral direction.

The light collecting element 35 (the lens 36) is provided for each of the antennas 32, as in the example illustrated in Fig. 3. For example, the lens 36 is so provided as to be stacked with respect to the wiring layer 90, and is positioned above the antenna 32. The antenna 32 may transmit and receive the optical signal via the lens 36. In the photodetector 1, for example, a plurality of lenses 36 is disposed side by side in the X-axis direction and the Y-axis direction. The scanner 30 may include a microlens array including the plurality of lenses 36 (microlenses).

The lens 36 includes, for example, a resin material, a glass material, or the like. The lens 36 may include silicon oxide (SiO), silicon nitride (SiN), or amorphous silicon (a-Si), or may include another material. Note that a configuration (a shape, a size, etc.) of the lens 36 is not limited to the illustrated example, and may be changed as appropriate.

Note that the light collecting element 35 may include 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 including a nanostructure, and may be configured as a metalens (a metamaterial lens). The metalens as the light collecting element 35 may include, for example, a metal, a metal compound (such as a metal oxide or a metal nitride), a silicon compound, or the like, or may include another material.

As described above, the photodetector 1 according to the present embodiment includes the splitter 20, the scanner 30, and the light reception circuit 40 each provided on the substrate 101. It is thus possible to obtain the photodetector 1 having favorable detection performance. For example, it is possible to obtain a photodetector (a ranging device) having favorable performance as an OCT device.

In the photodetector 1, the light collecting element 35 may be provided for each of the antennas 32, as in the example illustrated in Fig. 3. One light collecting element 35 (e.g., one lens 36) is provided for one antenna 32. This makes it possible to appropriately guide light (the optical signal) toward the measurement target, and to improve measurement accuracy.

In addition, the photodetector 1 may include a spacer layer 95 (also referred to as a spacer), as in the example illustrated in Fig. 3. The spacer layer 95 is provided, for example, between the light collecting element 35 and the wiring layer 90. For example, the spacer layer 95 includes the same material as the lens 36, and is positioned between the lens 36 and the antenna 32. The spacer layer 95 may include a material different from that of the lens 36.

The spacer layer 95 has a thickness (a height) that may be set so that the light from the antenna 32 is collected toward the measurement target. For example, the thickness (the height) of the spacer layer 95 in the Z-axis direction is determined so that the living body (the skin) to be the measurement target is in focus. This makes it possible to efficiently collect the light toward the measurement target. It is possible to improve the measurement accuracy.

Fig. 4 is a diagram illustrating a configuration example of the photodetector according to the embodiment. In the example illustrated in Fig. 4, the photodetector 1 includes a plurality of light sources 10 (in Fig. 4, a light source 10a, a light source 10b, a light source 10c, and a light source 10d). The light sources 10a to 10d may be configured to generate and output respective optical signals in wavelength bands different from each other.

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

The optical circuit 50 is provided in common to the plurality of light sources 10, for example. In the example illustrated 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 by using, for example, laser light inputted from the light sources 10a to 10d via a waveguide element 12.

For example, the waveguide element 12 is configured to transmit, to the output circuit 50, at least one of the respective rays of the output light of the light sources 10a to 10d. For example, the waveguide element 12 may 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, or the output light from the light source 10d.

In addition, for example, the waveguide element 12 may be configured to transmit, to the splitter 20 of the optical circuit 50, an optical signal in which the respective rays of the output light of the light sources 10a to 10d emitted in a time-division manner are multiplexed (combined). The waveguide element 12 may also be referred to as a multiplexing element. Note that the optical circuit 50 may include the waveguide element 12 (the multiplexing element).

As described above, the photodetector 1 includes the plurality of light sources 10, and is configured to perform measurement with use of the optical signals in respective wavelength ranges different from each other. For example, it is therefore possible to acquire information for each wavelength as a measurement result, and to improve the measurement accuracy. It is possible to perform ranging with high accuracy. In addition, it is possible to measure a plurality of biomarkers.

The signal processing circuit 70 of the photodetector 1 may perform a process of combining (synthesizing) signals (pieces of information) as measurement results obtained by transmission and reception of the optical signals in the respective wavelength bands. This makes it possible to improve resolution in a plane direction or a depth direction. For example, it is possible to improve ranging accuracy and resolution of the tomographic image.

In addition, as in a case of the example illustrated in Fig. 4, the transmission and reception of the optical signals in the respective wavelength bands via the scanner 30 of the common optical circuit 50 makes it possible to prevent misalignment of an irradiation position of the optical signal (a beam) from occurring. It is thus possible to prevent, for example, a decrease in accuracy of identification of the biomarker.

Fig. 5 is a diagram illustrating another configuration example of the photodetector according to the embodiment. The optical circuit 50 may be provided for each of the light sources 10. In the example illustrated in Fig. 5, one optical circuit 50 is provided for one light source 10. The optical circuit 50 is configured to transmit and receive the optical signal with use of, for example, laser light inputted from corresponding one of the light sources 10.

As in a case of the example illustrated in Fig. 5, in a case where the optical circuit 50 is provided for each of the light sources 10, it is possible to provide the optical circuit 50 with an optical characteristic suitable for the wavelength band of the output light of corresponding one of the light sources 10, and to reduce light loss. For example, it is possible to suppress a decrease in S/N ratio of the optical signal due to wavelength dependency of a characteristic of the optical circuit 50.

Fig. 6 is a diagram illustrating another configuration example of the photodetector according to the embodiment. A common optical circuit 50 may be provided for multiple light sources 10 (in Fig. 6, the light source 10a and the light source 10b) that output respective optical signals in wavelength bands relatively close to each other. In addition, separate optical circuits 50 may be provided for multiple light sources 10 (in Fig. 6, the light source 10c and the light source 10d) that output respective optical signals in wavelength bands relatively far from each other.

Figs. 7 to 10 are each a diagram for describing an arrangement example of the antennas of the photodetector according to the embodiment. Figs. 7 to 10 each illustrate the arrangement example of the antennas 32 of each of the optical circuits 50 in a case where the photodetector 1 includes a plurality of optical circuits 50 (e.g., the optical circuits 50a to 50d).

Each of the drawings illustrate the antenna 32 (an antenna 32a) of the optical circuit 50a, the antenna 32 (an antenna 32b) of the optical circuit 50b, the antenna 32 (an antenna 32c) of the optical circuit 50c, and the antenna 32 (an antenna 32d) of the optical circuit 50d.

A plurality of antennas 32a coupled to the switch unit 31 of the optical circuit 50a and a plurality of antennas 32b coupled to the switch unit 31 of the optical circuit 50b may be arranged, for example, as illustrated in Fig. 7. A part of the plurality of antennas 32a is provided between any two, of the plurality of adjacent antennas 32b, that are adjacent to each other.

In addition, in the example illustrated in Fig. 7, a part of the plurality of antennas 32b is provided between any two, of the plurality of adjacent antennas 32a, that are adjacent to each other. The antennas 32a and the antennas 32b may be provided in a checkerboard pattern, for example. The antennas 32a and the antennas 32b may be alternately provided.

In the photodetector 1, as in the example illustrated in Fig. 8, multiple antennas 32a arranged side by side in the Y-axis direction (or the X-axis direction) and multiple antennas 32b arranged side by side in the Y-axis direction (or the X-axis direction) may be repeatedly arranged. Arranging the antennas 32a and 32b as in the example illustrated in Fig. 7 or Fig. 8 makes it possible to suppress the misalignment of the irradiation position of the optical signal.

As in the example illustrated in Fig. 9, the antennas 32a, the antennas 32b, the antennas 32c, and the antennas 32d may be provided in a mixed manner. For example, the photodetector 1 may have a row 115 in which the antennas 32a and the antennas 32b are alternately arranged, and a row 116 in which the antennas 32c and the antennas 32d are alternately arranged.

In the photodetector 1, for example, a plurality of waveguides may be so provided in a crossing manner as to correspond to the respective arrangement positions of the antennas 32 (e.g., the antennas 32a to 32d). In addition, for example, a waveguide having a two-layer structure may be provided. Note that the respective numbers of the provided antennas 32a to 32d may be the same as each other, or may be different from each other.

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

In a case where measurement is performed of a biomarker that requires a high S/N ratio, with the optical signal transmitted and received via a particular antenna, e.g., the antenna 32c, the antennas 32c may be provided more than other antennas (e.g. the antennas 32a or 32b). In the example illustrated in Fig. 10, the number of the antennas 32c is greater than the number of the antennas 32a and is also greater than the number of the antennas 32b. In view of Figs. 7-10, it may be said that the antennas 32 are arranged in an array such that immediately adjacent antennas 32 in at least one direction output different wavelength ranges of light. In addition, it may be said that there are subsets of light sources 10, with each light source 10 being associated with a different antenna 32 such that the subsets of light sources are distributed in a pattern within the array.

Figs. 11 and 12 are each a diagram for describing a configuration example of the photodetector according to the embodiment. Fig. 11 illustrates an example of a cross-sectional configuration of the photodetector, and Fig. 12 illustrates an example of a plan configuration of the scanner of the photodetector. The photodetector 1 may be so configured that a straight line passing through a center of the antenna 32 and an optical axis of the light collecting element 35 are shifted from each other.

For example, the photodetector 1 is so configured that an optical axis L1 of the lens 36 as the light collecting element 35 is shifted from a center line L2 passing through the center of the antenna 32. For example, the optical axis L1 of the lens 36 is shifted in the X-axis direction (or the Y-axis direction) with respect to the center line L2 passing through the center of the antenna 32 (i.e., the diffraction grating).

In the example illustrated in Fig. 11, the lens 36 is so provided that the optical axis L1 of the lens 36 is shifted in a horizontal direction (e.g., a left direction) with respect to the center line L2 of the antenna 32. Thus configuring the photodetector 1 makes it possible to appropriately guide oblique light emitted from the antenna 32 to the measurement target, as schematically indicated by a solid-line arrow in Fig. 11. It may be said that the lens 36 has at least one focal point that is offset from a center line of the antenna structure 30 in a lateral direction. In Fig. 11, the lens 36 may be substantially symmetrical (e.g., along a line that passes through a center point of the lens 36). As depicted in Figs. 11 and 14, for example, the lens 36 may have a curvature that peaks at a point that is offset from the center line of an antenna 32 in the lateral direction.

The transmitted light traveling in an oblique direction from the antenna 32 is corrected by the lens 36 to travel in, for example, a vertical direction (the Z-axis direction). This allows the transmitted light (i.e., the optical signal S1) to be efficiently guided to the measurement target (e.g., the skin). It is thus possible to achieve a short working distance (e.g., a short distance from the photodetector 1 to the skin as the measurement target).

According to the photodetector 1 of the present embodiment, it is possible to obtain a wearable device that is able to deal with a short working distance. In addition, configuring the photodetector 1 as described above make it possible to cause the transmitted light to be incident perpendicularly on the skin as the measurement target, which makes it possible to perform sensing to a deep region.

Fig. 13 is a diagram for describing another configuration example of the photodetector according to the embodiment. The photodetector 1 may be so configured that the optical axis of the light collecting element 35 is inclined with respect to the straight line passing through the center of the antenna 32. For example, the lens 36 as the light collecting element 35 is so provided that the optical axis L1 of the lens 36 is inclined with respect to the center line L2 of the antenna 32 (i.e., the diffraction grating). In the example of Fig. 13 (and the example of Fig. 14 described below), it be said that the lens 36 is asymmetrical (e.g., along a line that passes through a center point of the lens 36). In Fig. 13, the lens 36 may have a curvature that peaks at a point that aligns with the center line of an antenna 32.

As in the example illustrated in Fig. 13, the lens 36 may be so disposed obliquely (in an inclined manner) that the oblique light emitted from the antenna 32 passes through a center portion of the lens 36. Thus configuring the photodetector 1 makes it possible to efficiently collect the oblique light emitted from the antenna 32. It is possible to improve light collecting efficiency and to improve sensitivity.

In addition, it is possible to cause the transmitted light to be incident obliquely on the skin as the measurement target, and to reduce a reflection component from a surface of the skin as the reflected light (the received light). It is thus possible to, for example, reduce a noise component due to the reflected light at the surface of the skin, and to perform sensing of the blood component with high accuracy.

Fig. 14 is a diagram for describing another configuration example of the photodetector according to the embodiment. Fig. 14 illustrates an arrangement example, in a case where the photodetector 1 includes a plurality of optical circuits 50 (e.g., the optical circuit 50a and the optical circuit 50b), of the respective antennas 32 and the respective lenses 36 of the optical circuits 50.

In addition, Fig. 14 illustrates the antenna 32a of the optical circuit 50a, a center line L2a of the antenna 32a, a lens 36a of the optical circuit 50a, an optical axis L1a of the lens 36a, the antenna 32b of the optical circuit 50b, a center line L2b of the antenna 32b, a lens 36b of the optical circuit 50b, and an optical axis L1b of the lens 36b.

In the photodetector 1, the respective antennas 32 and the respective lenses 36 of the optical circuits 50 may be so provided that rays of the transmitted light having different wavelengths overlap each other. For example, as illustrated in Fig. 14, the photodetector 1 is so configured that an irradiation position of transmitted light of a wavelength A1 to be outputted from the antenna 32a and an irradiation position of transmitted light of a wavelength B1 to be outputted from the antenna 32b substantially coincide with each other. This makes it possible to suppress misalignment of the irradiation positions of the optical signals of the respective wavelengths.

Figs. 15A to 15F are each a diagram illustrating an example of a manufacturing method of the photodetector according to the embodiment. First, as illustrated in Fig. 15A, the substrate 101 such as an SOI substrate is prepared. Thereafter, as illustrated in Fig. 15B, the waveguide 15, the antenna 32, etc. are formed in the semiconductor layer 110 of the substrate 101. Thereafter, as illustrated in Fig. 15C, the light reception element 46, the heater 38, etc. are sequentially formed on the surface 11S1 side of the semiconductor layer 110 to form the wiring layer 90.

Thereafter, as illustrated in Fig. 15D, a portion of each of the wiring layer 90, the semiconductor layer 110, and the insulating layer 105 is 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., the electrode 92 is formed on the semiconductor layer 120 as illustrated in Fig. 15D.

Thereafter, as illustrated in Fig. 15E, the light source 10 provided with the electrode 91 is flip-chip bonded to the substrate 101 provided with the electrode 92. Thereafter, as illustrated in Fig. 15F, the spacer layer 95, the lens 36, etc. are formed. It is possible to manufacture the photodetector 1 illustrated in Fig. 3, etc. by the manufacturing method described above. Note that the above-described manufacturing method of the photodetector is merely an example, and another manufacturing method may be employed.
<Workings and Effects>

The photodetector according to the present embodiment includes a splitter (the splitter 20), a scanner (the scanner 30), and a light reception circuit (the light reception circuit 40). The splitter (the splitter 20) is provided on a substrate (the substrate 101), and is configured to transmit an optical signal and a reference signal. The optical signal is based on output light of a light source (the light source 10). The scanner (the scanner 30) is provided on the substrate, and is configured to output the optical signal transmitted from the splitter. The light reception circuit (the light reception circuit 40) is provided on the substrate, and is configured to receive the optical signal reflected by a target, and the reference signal.

The photodetector (the photodetector 1) according to the present embodiment includes: the splitter 20 configured to transmit the optical signal S1 based on the output light of the light source 10, and the reference signal S2; the scanner 30 configured to output the optical signal S1 transmitted from the splitter 20; and the light reception circuit 40 configured to receive the optical signal S3, which is the reflected light, and the reference signal S2. The splitter 20, the scanner 30, and the light reception circuit 40 are each provided on the substrate 101. It is thus possible to obtain a photodetector having favorable performance.

Next, modification examples of the present disclosure will be described. In the following, components similar to those in the above-described embodiment are denoted with the same reference numerals, and descriptions thereof will be omitted as appropriate.
<2. Modification Examples>
<2-1. Modification Example 1>

The configuration examples of the photodetector 1 have been described in the embodiment above; however, they are merely examples, and the configuration of the photodetector 1 is not limited to the above-described examples. Fig. 16 is a diagram illustrating a configuration example of a photodetector according to Modification example 1 of the present disclosure. For example, the photodetector 1 may include an attenuator 16. The attenuator 16 is an optical attenuator, and is configured to attenuate the reference signal S2.

The optical circuit 50 includes, for example, a variable optical attenuator (VOA: Variable Optical Attenuator) as the attenuator 16. The attenuator 16 is provided, for example, between the splitter 20 and the mixer 41. In the present modification example, provision of the attenuator 16 makes it possible to adjust a signal intensity of the reference signal S2 in accordance with a signal intensity (power) of the optical signal S3 which is the feedback light.
<2-2. Modification Example 2>

Fig. 17 is a diagram illustrating a configuration example of a photodetector according to Modification example 2. The photodetector 1 may include a measurer 14. The measurer 14 is configured to measure a state of the output light of the light source 10. In the example illustrated in Fig. 17, the photodetector 1 includes a splitter 13. In the photodetector 1, the splitter 13 transmits a portion of the output light of the light source 10 to the measurer 14.

The measurer 14 is configured to measure the state (e.g., an intensity, a wavelength, a phase, etc. of light) of the output light of the light source 10 on the basis of the output light (the optical signal) of the light source 10 to be inputted via the splitter 13. The measurer 14 includes, for example, an interferometer, a resonator, or both, and a photodetection unit.

The measurer 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 measurer 14 may be configured as, for example, a device (a monitoring device) that monitors an oscillation state, etc. of the laser light from the light source 10. Note that the measurer 14 may also be referred to as a determination unit (a determination circuit) configured to determine the state of the output light of the light source 10. For example, the measurer 14 may generate a signal related to the state of the output light of the light source 10, and may output the generated signal to the signal processing circuit 70.

The signal processing circuit 70 may control the light source 10, the generation process of the interference signal by the light reception circuit 40, etc. on the basis of an output signal of the measurer 14. In addition, for example, the signal processing circuit 70 is configured to change the signal processing to be performed by the signal processing circuit 70, in accordance with the output signal of the measurer 14. Performing such a feedback control makes it possible to improve the measurement accuracy of the photodetector 1.
<2-3. Modification Example 3>

Fig. 18 is a diagram illustrating a configuration example of a photodetector according to Modification example 3. The photodetector 1 may include a polarizer 17. The polarizer 17 is provided, for example, between the light source 10 and the splitter 20 in the optical circuit 50. Provision of the polarizer 17 makes it possible to remove an unnecessary polarization component of the output light of the optical circuit 50, and to reduce noise.

In addition, the photodetector 1 may include a measurer 18 configured to measure an ambient temperature. The measurer 18 is a temperature detection device, and is configured to detect the ambient temperature. For example, the measurer 18 is provided around each of the circuits or the elements of the optical circuit 50. The measurer 18 may generate a signal related to a temperature (e.g., a signal related to a temperature of the element of the optical circuit 50), and may output the generated signal to, for example, the signal processing circuit 70.

The signal processing circuit 70 may control each of the circuits (the splitter 20, the switch unit 31 and the antenna 32 of the scanner 30, the light reception circuit 40, the attenuator 16, etc.) of the optical circuit 50 on the basis of an output signal of the measurer 18. In the photodetector 1 according to the present modification example, monitoring the temperature and performing the feedback control makes it possible to achieve a stable operation.
<2-4. Modification Example 4>

Fig. 19 is a diagram illustrating a configuration example of a photodetector according to Modification example 4. The photodetector 1 may include an isolator 19. The isolator 19 is provided, for example, in the optical circuit 50, between the light source 10 and the splitter 20. In the present modification example, provision of the isolator 19 makes it possible to prevent deterioration of the S/N ratio due to the feedback light to the light source 10.
<2-5. Modification Example 5>

Fig. 20 is a diagram illustrating a configuration example of a photodetector according to Modification example 5. The photodetector 1 may be provided with a circulator 25. For example, the circulator 25 has three ports (a port 26a, a port 26b, and a port 26c), and is configured to transmit the optical signal among the ports. In the example illustrated in Fig. 20, the port 26a, the port 26b, and the port 26c are optically coupled to the splitter 20, the scanner 30, and the mixer 41, respectively.

The port 26a of the circulator 25 receives, for example, the optical signal S1, which is the frequency-modulated laser light, from the splitter 20. The circulator 25 may output the optical signal S1 inputted to the port 26a, from the port 26b to the scanner 30. The port 26b of the circulator 25 receives the optical signal S3, which is the received light (the reflected light) from the scanner 30.

The circulator 25 may output the optical signal S3 inputted to the port 26b, from the port 26c to the mixer 41. In the present modification example, provision of the circulator 25 makes it possible to transmit the optical signal S3, which is the received light, to the mixer 41 without loss (loss), and to improve the S/N ratio of the optical signal (or the interference signal).
<2-6. Modification Example 6>

Figs. 21 and 22 are each a diagram illustrating a configuration example of a photodetector according to Modification example 6. As in the example illustrated in Fig. 21, the photodetector 1 may include a mark 96 to be used for alignment. The mark 96 may include a metal material, or may include another material.

The mark 96 is an alignment mark, and is provided, for example, in the wiring layer 90. In the example illustrated in Fig. 21, the mark 96 is provided in the wiring layer 90, around the lens 36 as the light collecting element 35. Note that a shape, an arrangement, etc. of the mark 96 may be changed as appropriate.

In the example illustrated in Fig. 22, the photodetector 1 is provided with a counterboring part 97. For example, the counterboring part 97 is a recessed part (a groove part), and is provided in the wiring layer 90. The spacer layer 95 and the light collecting element 35 are so disposed as to be positioned at the counterboring part 97, as in the example illustrated in Fig. 22.

In the photodetector 1 according to the present modification example, provision of the mark 96, the counterboring part 97, or both makes it possible to align and dispose the light collecting element 35 (e.g., the lens 36). It is thus possible to suppress characteristic deterioration due to misalignment of the light collecting element 35 (the lens 36).
<2-7. Modification Example 7>

Figs. 23 and 24 are each a diagram illustrating a configuration example of a photodetector according to Modification example 7. Fig. 23 illustrates an example of a cross-sectional configuration of the photodetector, and Fig. 24 illustrates an example of a plan configuration of a scanner of the photodetector. The photodetector 1 may include a light blocking member 80, as in the example illustrated in each of Figs. 23 and 24. The light blocking member 80 is a light blocking part (a light blocking film) including a member that blocks light.

The light blocking member 80 (the light blocking part) is provided around the antenna 32, the light reception element 46, or both. For example, the light blocking member 80 is provided around the antenna 32, as in the example illustrated in Fig. 23 or Fig. 24, and suppresses incidence of unnecessary light on the antenna 32. Note that the scanner 30 may include the light blocking member 80.

The light blocking member 80 is provided, for example, next to the antenna 32 in the substrate 101. For example, the light blocking member 80 is provided for each of the antennas 32, and is also provided between any two, of the antennas 32, that are adjacent to each other. In addition, the light blocking member 80 may be disposed between the antenna 32 and the light reception unit 45 (or the light reception element 46), as in the example illustrated in Fig. 23.

For example, the light blocking member 80 is so provided as to reach the surface 11S2 of the semiconductor layer 110 from below the spacer layer 95. The light blocking member 80 may be provided to extend in the thickness direction orthogonal to the surface 11S1 (or the surface 11S2) of the semiconductor layer 110, i.e., in the Z-axis direction, and to reach the semiconductor layer 120. The light blocking member 80 may be provided through the semiconductor layer 110.

In the example illustrated in Fig. 23, the light blocking member 80 is so provided around the antenna 32 as to extend through the semiconductor layer 110 and the insulating layer 105 and reach the semiconductor layer 120. For example, the light blocking member 80 has a through via. The light blocking member 80 receives a predetermined potential (voltage), for example, a GND potential (a ground potential), via the wiring, the via, etc. of the wiring layer 90.

The light blocking member 80 may be so provided as to surround the antenna 32 in a plan view. The light blocking member 80 is provided for each of the antennas 32. For example, as in the example illustrated in Fig. 24, the light blocking member 80 may be provided to partially surround the antenna 32 in a plan view (i.e., in a case of being viewed in an XY plane).

The light blocking member 80 includes, for example, tungsten (W). Note that the light blocking member 80 may include another metal material that blocks light such as aluminum (Al) or copper (Cu). The light blocking member 80 may include a metal compound.

For example, the light blocking member 80 may include a material having a refractive index lower than that of a surrounding member, and may have a cavity (a gap). In addition, the light blocking member 80 may include a material that absorbs light. The light blocking member 80 may also be referred to as a light blocking wall that blocks incident light.

In the photodetector 1 according to the present modification example, provision of the light blocking member 80 around the antenna 32, around the light reception element 46, etc. makes it possible to suppress incidence of unnecessary light (e.g., stray light) on the antenna 32, the light reception element 46, etc. For example, it is possible to suppress occurrence of an error in ranging due to mixing of a stray light component having a frequency different from the frequency of the optical signal. It is possible to improve the measurement accuracy.
<2-8. Modification Example 8>

Figs. 25 and 26 are each a diagram illustrating a configuration example of a photodetector according to Modification example 8. Fig. 25 illustrates an example of a cross-sectional configuration of the photodetector, and Fig. 26 illustrates an example of a plan configuration of the photodetector. The photodetector 1 may include a mirror 34, as in the example illustrated in each of Figs. 25 and 26. In addition, the photodetector 1 may include a housing member 150.

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

As schematically illustrated by a dotted line in Fig. 25, the optical signal S1 is incident on the mirror 34 via the waveguide 15 of (the switch unit 31 of) the scanner 30. The mirror 34 reflects the optical signal S1 to the light collecting element 35 (e.g., the lens 36) side. The scanner 30 may emit, for example, the optical signal S1 that is to be the frequency-modulated laser light, to the measurement target as the transmitted light, by the mirror 34, the light collecting element 35, etc.

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

The photodetector 1 may be so configured that a straight line L3 passing through the mirror 34 and the optical axis of the light collecting element 35 are shifted from each other. The straight line L3 is, for example, a perpendicular line passing through an intersection P of an extended line of the waveguide 15 in the X-axis direction (or the Y-axis direction) and a mirror surface. The straight line L3 may be a perpendicular line passing through a point of arrival (i.e., an incident point) of the light in the mirror 34. For example, as in the example illustrated in Fig. 25, the photodetector 1 may be so configured that the optical axis L1 of the lens 36 is inclined with respect to the straight line L3. The lens 36 is so provided obliquely that oblique light from the mirror 34 passes through the center of the lens 36.

Configuring the photodetector 1 as described above makes it possible to efficiently collect the oblique light from the mirror 34. Causing the transmitted light to incident obliquely on the skin to be measured makes it possible to reduce noise due to the reflected light, and to improve the measurement accuracy. For example, it is possible to accurately perform the sensing of the blood component.

A plurality of waveguides 15 and a plurality of mirrors 34 of the photodetector 1 may be provided on a part or all of sides of the substrate 101. For example, as in the example schematically illustrated in Fig. 26, the plurality of waveguides 15 and the plurality of mirrors 34 may be disposed along four sides of the substrate 101. Thus configuring the photodetector 1 makes it possible, for example, to increase the number of measurement points (i.e., region parts for which transmission and reception of the optical signal is to be performed), and to improve the measurement accuracy.

Note that the lens 36 may be so provided that the optical axis L1 of the lens 36 is positioned to be shifted in the X-axis direction (or the Y-axis direction) with respect to the straight line L3. Thus configuring the photodetector 1 makes it possible to correct, by the lens 36, the oblique light from the mirror 34 to travel in the vertical direction (the Z-axis direction), and to efficiently guide the transmitted light to the measurement target.

As in the case of the example illustrated in Fig. 11, it is possible to obtain a device that is able to deal with a short working distance. In addition, it is possible to cause the transmitted light to be incident perpendicularly on the skin to be measured, and to perform sensing to a deep region. In the case of the present modification example also, it is possible to achieve effects similar to those of the above-described embodiment.
<3. Use Examples>

The above-described photodetector may be used, for example, in various cases where sensing is performed of light such as visible light, infrared light, ultraviolet light, or X-rays, as described below.
- Apparatuses that capture images to be viewed, such as: a digital camera; or a mobile apparatus with a camera function.
- Apparatuses for traffic use such as: an in-vehicle sensor that captures images of a front region, a rear region, a surrounding region, an inside region, etc. of an automobile for safe driving such as automatic stopping or recognition of the driver's state; a monitoring camera that monitors traveling vehicles and roads; or a ranging sensor that measures a vehicle-to-vehicle distance.
- Apparatuses for home appliance such as a television, a refrigerator, or an air conditioner, to capture an image of a gesture of a user and allow for an apparatus operation according to the gesture.
- Apparatuses for medical use or heath care use such as: an endoscope; or an apparatus that performs angiography by infrared-light reception.
- Apparatuses for security use such as: a monitoring camera for crime prevention use; or a camera for human identification use.
- Apparatuses for beauty use such as: a skin measurement apparatus that captures an image of skin; or a microscope that captures an image of a scalp.
- Apparatuses for sports use such as: an action camera or a wearable camera for sports use, etc.
- Apparatuses for agriculture use such as a camera for monitoring a state of fields and crops.
<4. Application Examples>
<Example of Application to Endoscopic Surgery System>

A technique (the present technology) according to the present disclosure is applicable to various products. For example, the technique according to the present disclosure may be applied to an endoscopic surgery system.

Fig. 27 is a view depicting an example of a schematic configuration of an endoscopic surgery system to which the technology according to an embodiment of the present disclosure (present technology) can be applied.

In Fig. 27, a state is illustrated in which a surgeon (medical doctor) 11131 is using an endoscopic surgery system 11000 to perform surgery for a patient 11132 on a patient bed 11133. As depicted, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical tools 11110 such as a pneumoperitoneum tube 11111 and an energy device 11112, a supporting arm apparatus 11120 which supports the endoscope 11100 thereon, and a cart 11200 on which various apparatus for endoscopic surgery are mounted.

The endoscope 11100 includes a lens barrel 11101 having a region of a predetermined length from a distal end thereof to be inserted into a body cavity of the patient 11132, and a camera head 11102 connected to a proximal end of the lens barrel 11101. In the example depicted, the endoscope 11100 is depicted which includes as a rigid endoscope having the lens barrel 11101 of the hard type. However, the endoscope 11100 may otherwise be included as a flexible endoscope having the lens barrel 11101 of the flexible type.

The lens barrel 11101 has, at a distal end thereof, an opening in which an objective lens is fitted. A light source apparatus 11203 is connected to the endoscope 11100 such that light generated by the light source apparatus 11203 is introduced to a distal end of the lens barrel 11101 by a light guide extending in the inside of the lens barrel 11101 and is irradiated toward an observation target in a body cavity of the patient 11132 through the objective lens. It is to be noted that the endoscope 11100 may be a forward-viewing endoscope or may be an oblique-viewing endoscope or a side-viewing endoscope.

An optical system and an image pickup element are provided in the inside of the camera head 11102 such that reflected light (observation light) from the observation target is collected on the image pickup element by the optical system. The observation light is photo-electrically converted by the image pickup element to generate an electric signal corresponding to the observation light, namely, an image signal corresponding to an observation image. The image signal is transmitted as RAW data to a CCU 11201.

The CCU 11201 includes a central processing unit (CPU), a graphics processing unit (GPU) or the like and integrally controls operation of the endoscope 11100 and a display apparatus 11202. Further, the CCU 11201 receives an image signal from the camera head 11102 and performs, for the image signal, various image processes for displaying an image based on the image signal such as, for example, a development process (demosaic process).

The display apparatus 11202 displays thereon an image based on an image signal, for which the image processes have been performed by the CCU 11201, under the control of the CCU 11201.

The light source apparatus 11203 includes a light source such as, for example, a light emitting diode (LED) and supplies irradiation light upon imaging of a surgical region to the endoscope 11100.

An inputting apparatus 11204 is an input interface for the endoscopic surgery system 11000. A user can perform inputting of various kinds of information or instruction inputting to the endoscopic surgery system 11000 through the inputting apparatus 11204. For example, the user would input an instruction or a like to change an image pickup condition (type of irradiation light, magnification, focal distance or the like) by the endoscope 11100.

A treatment tool controlling apparatus 11205 controls driving of the energy device 11112 for cautery or incision of a tissue, sealing of a blood vessel or the like. A pneumoperitoneum apparatus 11206 feeds gas into a body cavity of the patient 11132 through the pneumoperitoneum tube 11111 to inflate the body cavity in order to secure the field of view of the endoscope 11100 and secure the working space for the surgeon. A recorder 11207 is an apparatus capable of recording various kinds of information relating to surgery. A printer 11208 is an apparatus capable of printing various kinds of information relating to surgery in various forms such as a text, an image or a graph.

It is to be noted that the light source apparatus 11203 which supplies irradiation light when a surgical region is to be imaged to the endoscope 11100 may include a white light source which includes, for example, an LED, a laser light source or a combination of them. Where a white light source includes a combination of red, green, and blue (RGB) laser light sources, since the output intensity and the output timing can be controlled with a high degree of accuracy for each color (each wavelength), adjustment of the white balance of a picked up image can be performed by the light source apparatus 11203. Further, in this case, if laser beams from the respective RGB laser light sources are irradiated time-divisionally on an observation target and driving of the image pickup elements of the camera head 11102 are controlled in synchronism with the irradiation timings. Then images individually corresponding to the R, G and B colors can be also picked up time-divisionally. According to this method, a color image can be obtained even if color filters are not provided for the image pickup element.

Further, the light source apparatus 11203 may be controlled such that the intensity of light to be outputted is changed for each predetermined time. By controlling driving of the image pickup element of the camera head 11102 in synchronism with the timing of the change of the intensity of light to acquire images time-divisionally and synthesizing the images, an image of a high dynamic range free from underexposed blocked up shadows and overexposed highlights can be created.

Further, the light source apparatus 11203 may be configured to supply light of a predetermined wavelength band ready for special light observation. In special light observation, for example, by utilizing the wavelength dependency of absorption of light in a body tissue to irradiate light of a narrow band in comparison with irradiation light upon ordinary observation (namely, white light), narrow band observation (narrow band imaging) of imaging a predetermined tissue such as a blood vessel of a superficial portion of the mucous membrane or the like in a high contrast is performed. Alternatively, in special light observation, fluorescent observation for obtaining an image from fluorescent light generated by irradiation of excitation light may be performed. In fluorescent observation, it is possible to perform observation of fluorescent light from a body tissue by irradiating excitation light on the body tissue (autofluorescence observation) or to obtain a fluorescent light image by locally injecting a reagent such as indocyanine green (ICG) into a body tissue and irradiating excitation light corresponding to a fluorescent light wavelength of the reagent upon the body tissue. The light source apparatus 11203 can be configured to supply such narrow-band light and/or excitation light suitable for special light observation as described above.

Fig. 28 is a block diagram depicting an example of a functional configuration of the camera head 11102 and the CCU 11201 depicted in Fig. 27.

The camera head 11102 includes a lens unit 11401, an image pickup unit 11402, a driving unit 11403, a communication unit 11404 and a camera head controlling unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412 and a control unit 11413. The camera head 11102 and the CCU 11201 are connected for communication to each other by a transmission cable 11400.

The lens unit 11401 is an optical system, provided at a connecting location to the lens barrel 11101. Observation light taken in from a distal end of the lens barrel 11101 is guided to the camera head 11102 and introduced into the lens unit 11401. The lens unit 11401 includes a combination of a plurality of lenses including a zoom lens and a focusing lens.

The number of image pickup elements which is included by the image pickup unit 11402 may be one (single-plate type) or a plural number (multi-plate type). Where the image pickup unit 11402 is configured as that of the multi-plate type, for example, image signals corresponding to respective R, G and B are generated by the image pickup elements, and the image signals may be synthesized to obtain a color image. The image pickup unit 11402 may also be configured so as to have a pair of image pickup elements for acquiring respective image signals for the right eye and the left eye ready for three dimensional (3D) display. If 3D display is performed, then the depth of a living body tissue in a surgical region can be comprehended more accurately by the surgeon 11131. It is to be noted that, where the image pickup unit 11402 is configured as that of stereoscopic type, a plurality of systems of lens units 11401 are provided corresponding to the individual image pickup elements.

Further, the image pickup unit 11402 may not necessarily be provided on the camera head 11102. For example, the image pickup unit 11402 may be provided immediately behind the objective lens in the inside of the lens barrel 11101.

The driving unit 11403 includes an actuator and moves the zoom lens and the focusing lens of the lens unit 11401 by a predetermined distance along an optical axis under the control of the camera head controlling unit 11405. Consequently, the magnification and the focal point of a picked up image by the image pickup unit 11402 can be adjusted suitably.

The communication unit 11404 includes a communication apparatus for transmitting and receiving various kinds of information to and from the CCU 11201. The communication unit 11404 transmits an image signal acquired from the image pickup unit 11402 as RAW data to the CCU 11201 through the transmission cable 11400.

In addition, the communication unit 11404 receives a control signal for controlling driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head controlling unit 11405. The control signal includes information relating to image pickup conditions such as, for example, information that a frame rate of a picked up image is designated, information that an exposure value upon image picking up is designated and/or information that a magnification and a focal point of a picked up image are designated.

It is to be noted that the image pickup conditions such as the frame rate, exposure value, magnification or focal point may be designated by the user or may be set automatically by the control unit 11413 of the CCU 11201 on the basis of an acquired image signal. In the latter case, an auto exposure (AE) function, an auto focus (AF) function and an auto white balance (AWB) function are incorporated in the endoscope 11100.

The camera head controlling unit 11405 controls driving of the camera head 11102 on the basis of a control signal from the CCU 11201 received through the communication unit 11404.

The communication unit 11411 includes a communication apparatus for transmitting and receiving various kinds of information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted thereto from the camera head 11102 through the transmission cable 11400.

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

The image processing unit 11412 performs various image processes for an image signal in the form of RAW data transmitted thereto from the camera head 11102.

The control unit 11413 performs various kinds of control relating to image picking up of a surgical region or the like by the endoscope 11100 and display of a picked up image obtained by image picking up of the surgical region or the like. For example, the control unit 11413 creates a control signal for controlling driving of the camera head 11102.

Further, the control unit 11413 controls, on the basis of an image signal for which image processes have been performed by the image processing unit 11412, the display apparatus 11202 to display a picked up image in which the surgical region or the like is imaged. Thereupon, the control unit 11413 may recognize various objects in the picked up image using various image recognition technologies. For example, the control unit 11413 can recognize a surgical tool such as forceps, a particular living body region, bleeding, mist when the energy device 11112 is used and so forth by detecting the shape, color and so forth of edges of objects included in a picked up image. The control unit 11413 may cause, when it controls the display apparatus 11202 to display a picked up image, various kinds of surgery supporting information to be displayed in an overlapping manner with an image of the surgical region using a result of the recognition. Where surgery supporting information is displayed in an overlapping manner and presented to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery with certainty.

The transmission cable 11400 which connects the camera head 11102 and the CCU 11201 to each other is an electric signal cable ready for communication of an electric signal, an optical fiber ready for optical communication or a composite cable ready for both of electrical and optical communications.

Here, while, in the example depicted, communication is performed by wired communication using the transmission cable 11400, the communication between the camera head 11102 and the CCU 11201 may be performed by wireless communication.

An example of the endoscopic surgery system to which the technique according to the present disclosure is applicable has been described above. The technique according to the present disclosure is favorably applicable to the image pickup unit 11402 provided in the camera head 11102 of the endoscope 11100, among the configurations described above. Applying the technique according to the present disclosure to the image pickup unit 11402 makes it possible to provide the endoscope 11100 with high resolution. According to the technique of the present disclosure, it is possible to dispose a miniaturized OCT device at a distal end of a lens barrel, which leads to expectation of obtaining an endoscope with higher definition.

Although the present disclosure has been described above with reference to the embodiment, the modification examples, the use examples, and the application examples, the present technology is not limited to the above-described embodiments and the like, and various modifications may be made. For example, the above-described modification examples have been described as modification examples of the above-described embodiment; however, the respective configurations of the modification examples may be combined as appropriate.

A photodetector according to one embodiment of the present disclosure includes a splitter, a scanner, and a light reception circuit. The splitter is provided on a substrate, and is configured to transmit an optical signal and a reference signal. The optical signal is based on output light of a light source. The scanner is provided on the substrate, and is configured to output the optical signal transmitted from the splitter. The light reception circuit is provided on the substrate, and is configured to receive the optical signal reflected by a target, and the reference signal. It is thus possible to obtain a photodetector having favorable performance.

Note that the effects described herein are merely examples and descriptions thereof are non-limiting. Any other effect may also be achieved. In addition, the present disclosure may have any of the following configurations.
(1) An optical device, comprising:
a first light source;
a multilayer structure;
a waveguide disposed in the multilayer structure and configured to receive light from the first light source;
a first antenna structure comprising a first antenna disposed in the multilayer structure and optically coupled to the waveguide; and
a lens structure on the multilayer structure and comprising a lens overlapped with the first antenna in a plan view, wherein, in a cross-sectional view, a center line of the first antenna passes through the lens, and wherein the lens has at least one focal point that is offset from the center line of the first antenna structure in a lateral direction.
(2) The optical device of (1), wherein the lens is substantially symmetrical.
(3) The optical device of one or more of (1) to (2), wherein the lens has a curvature that peaks at a point that is offset from the center line of the first antenna in the lateral direction.
(4) The optical device of one or more of (1) to (3), wherein the lens is asymmetrical.
(5) The optical device of one or more of (1) to (4), wherein the lens has a curvature that peaks at a point that aligns with the center line of the first antenna.
(6) The optical device of one or more of (1) to (5), wherein the first antenna structure comprises an optical grating.
(7) The optical device of one or more of (1) to (6), wherein the waveguide comprises silicon.
(8) The optical device of one or more of (1) to (7), wherein the lens structure further comprises a spacer positioned between the lens and the multilayer structure.
(9) The optical device of one or more of (1) to (8), wherein the multilayer structure further comprises a light detector to detect light.
(10) The optical device of one or more of (1) to (9), wherein the light detector is optically coupled to the first antenna structure.
(11) The optical device of one or more of (1) to (10), further comprising:
an optical splitter optically coupled between the first light source and the first antenna.
(12) The optical device of one or more of (1) to (11), further comprising:
an optical mixer optically coupled between the first light source and the light detector.
(13) The optical device of one or more of (1) to (12), further comprising:
an optical switch optically coupled between the optical splitter and the first antenna.
(14) The optical device of one or more of (1) to (13), wherein the first antenna structure further comprises a plurality of antennas including the first antenna, wherein each antenna is optically coupled to the optical switch.
(15) The optical device of one or more of (1) to (14), wherein the lens structure comprises a plurality of lenses with each lens overlapping a corresponding antenna in the plan view.
(16) The optical device of one or more of (1) to (15), further comprising:
a plurality of light sources including the first light source, each light source being configured to emit a different wavelength range of light;
a plurality of antennas including the first antenna optically coupled to the plurality of light sources; and
at least one optical switch optically coupled between the plurality of antennas and the plurality of light sources and configured to enable selection of subsets of the plurality of antennas to output one of the different wavelength ranges of light.
(17) The optical device of one or more of (1) to (16), wherein the plurality of antennas are arranged in an array, and wherein immediately adjacent antennas in at least one direction are configured to output different wavelength ranges of light.
(18) The optical device of one or more of (1) to (17), wherein each subset of the plurality of light sources are associated with a different antenna, and wherein the subsets of the plurality of light sources are distributed in a pattern within the array.
(19) An optical system, comprising:
a signal processing circuit; and
an optical device, comprising:
a first light source;
a multilayer structure;
a waveguide disposed in the multilayer structure and configured to receive light from the first light source;
a first antenna structure comprising a first antenna disposed in the multilayer structure and optically coupled to the waveguide; and
a lens structure on the multilayer structure and comprising a lens overlapped with the first antenna in a plan view, wherein, in a cross-sectional view, a center line of the first antenna passes through the lens, and wherein the lens has at least one focal point that is offset from the center line of the first antenna structure in a lateral direction.
(20) An optical device, comprising:
a first light source;
a multilayer structure;
a waveguide disposed in the multilayer structure and configured to receive light from the first light source;
a first antenna structure comprising a first antenna disposed in the multilayer structure and optically coupled to the waveguide;
a lens structure on the multilayer structure and comprising a lens overlapped with the first antenna in a plan view, wherein, in a cross-sectional view, a center line of the first antenna passes through the lens, and wherein the lens has at least one focal point that is offset from the center line of the first antenna structure in a lateral direction; and
a light detector disposed in the multilayer structure and configured to detect light reflected from an object.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Reference Numerals List

1 photodetector
10 light source
20 splitter
30 scanner
31 switch unit
32 antenna
40 light reception circuit
41 mixer
45 light reception unit
46 light reception element
60 amplifier circuit
70 signal processing circuit

Claims

An optical device, comprising:
a first light source;
a multilayer structure;
a waveguide disposed in the multilayer structure and configured to receive light from the first light source;
a first antenna structure comprising a first antenna disposed in the multilayer structure and optically coupled to the waveguide; and
a lens structure on the multilayer structure and comprising a lens overlapped with the first antenna in a plan view, wherein, in a cross-sectional view, a center line of the first antenna passes through the lens, and wherein the lens has at least one focal point that is offset from the center line of the first antenna structure in a lateral direction.
The optical device of claim 1, wherein the lens is substantially symmetrical.
The optical device of claim 1, wherein the lens has a curvature that peaks at a point that is offset from the center line of the first antenna in the lateral direction.
The optical device of claim 1, wherein the lens is asymmetrical.
The optical device of claim 1, wherein the lens has a curvature that peaks at a point that aligns with the center line of the first antenna.
The optical device of claim 1, wherein the first antenna structure comprises an optical grating.
The optical device of claim 6, wherein the waveguide comprises silicon.
The optical device of claim 1, wherein the lens structure further comprises a spacer positioned between the lens and the multilayer structure.
The optical device of claim 1, wherein the multilayer structure further comprises a light detector to detect light.
The optical device of claim 9, wherein the light detector is optically coupled to the first antenna structure.
The optical device of claim 9, further comprising:
an optical splitter optically coupled between the first light source and the first antenna.
The optical device of claim 11, further comprising:
an optical mixer optically coupled between the first light source and the light detector.
The optical device of claim 9, further comprising:
an optical switch optically coupled between the optical splitter and the first antenna.
The optical device of claim 13, wherein the first antenna structure further comprises a plurality of antennas including the first antenna, wherein each antenna is optically coupled to the optical switch.
The optical device of claim 14, wherein the lens structure comprises a plurality of lenses with each lens overlapping a corresponding antenna in the plan view.
The optical device of claim 1, further comprising:
a plurality of light sources including the first light source, each light source being configured to emit a different wavelength range of light;
a plurality of antennas including the first antenna optically coupled to the plurality of light sources; and
at least one optical switch optically coupled between the plurality of antennas and the plurality of light sources and configured to enable selection of subsets of the plurality of antennas to output one of the different wavelength ranges of light.
The optical device of claim 16, wherein the plurality of antennas are arranged in an array, and wherein immediately adjacent antennas in at least one direction are configured to output different wavelength ranges of light.
The optical device of claim 16, wherein each subset of the plurality of light sources are associated with a different light source, and wherein the subsets of the plurality of light sources are distributed in a pattern within the array.
An optical system, comprising:
a signal processing circuit; and
an optical device, comprising:
a first light source;
a multilayer structure;
a waveguide disposed in the multilayer structure and configured to receive light from the first light source;
a first antenna structure comprising a first antenna disposed in the multilayer structure and optically coupled to the waveguide; and
a lens structure on the multilayer structure and comprising a lens overlapped with the first antenna in a plan view, wherein, in a cross-sectional view, a center line of the first antenna passes through the lens, and wherein the lens has at least one focal point that is offset from the center line of the first antenna structure in a lateral direction.
An optical device, comprising:
a first light source;
a multilayer structure;
a waveguide disposed in the multilayer structure and configured to receive light from the first light source;
a first antenna structure comprising a first antenna disposed in the multilayer structure and optically coupled to the waveguide;
a lens structure on the multilayer structure and comprising a lens overlapped with the first antenna in a plan view, wherein, in a cross-sectional view, a center line of the first antenna passes through the lens, and wherein the lens has at least one focal point that is offset from the center line of the first antenna structure in a lateral direction; and
a light detector disposed in the multilayer structure and configured to detect light reflected from an object.