Photon integrated circuit and robot

Abstract

The invention relates to the technical field of sensors, and discloses a photon integrated circuit and a robot, the photon integrated circuit comprises a reflective optical amplifier, a wavelength selection mirror, a first tunable coupler, a second tunable coupler, a third tunable coupler, a first photoelectric detector and a second photoelectric detector; the first port is connected with the reflective optical amplifier, the third port is connected with the input end of the wavelength selection mirror, and the fourth port is connected with the output end of the wavelength selection mirror; the ninth port is used for receiving an echo optical signal, the tenth port is connected with the first photoelectric detector, and the eleventh port is connected with the second photoelectric detector; the second tunable coupler, the first photoelectric detector and the second photoelectric detector are all connected with the control unit, and the on-off states of the sixth port and the seventh port are controlled by the control unit through the phase shifter, so that the photon integrated circuit is configured as a laser radar or an optical fiber sensor. The control and wiring of the robot are simplified, and the cost, the power consumption and the size are reduced.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a photonic integrated circuit and a robot. Background Art

[0002] Robots possess capabilities similar to those of humans and other living things, such as perception, planning, movement, and coordination. They are highly flexible, autonomous machines. Robots incorporate numerous sensors, which enable them to perceive their environment and make autonomous adjustments. These sensors are the foundation for intelligent decision-making and precise movement. For example, robots use cameras and lidar for vision, as well as fiber optic sensors for temperature, pressure, and touch measurement.

[0003] However, each sensor has a control unit and its own wiring requirements. The use of multiple sensors can easily increase the complexity of the robot's control system and wiring, which not only increases the robot's power consumption and cost, but also increases the robot's size and weight. Summary of the Invention

[0004] In view of this, the present invention provides a photonic integrated circuit and a robot to improve the problem that the use of multiple sensors increases the complexity of the robot's control system and wiring.

[0005] In a first aspect, the present invention provides a photonic integrated circuit, which includes a reflective optical amplifier, a wavelength selective mirror, a first tunable coupler, a second tunable coupler, a third tunable coupler, a first photodetector, and a second photodetector; the first tunable coupler includes a first port, a second port, a third port, and a fourth port, the second tunable coupler includes a fifth port, a sixth port, and a seventh port, and the third tunable coupler includes an eighth port, a ninth port, a tenth port, and an eleventh port; the first port is connected to the reflective optical amplifier, the second port is connected to the fifth port, the third port is connected to the input end of the wavelength selective mirror, and the fourth port is connected to the input end of the wavelength selective mirror. The output end of the wavelength selective mirror is connected, the reflective optical amplifier is used to generate an initial optical signal, and the wavelength selective mirror is used to reflect the initial optical signal of the target wavelength to form a detection optical signal output from the second port; the sixth port is connected to the eighth port, the ninth port is used to receive the echo optical signal, the tenth port is connected to the first photodetector, and the eleventh port is connected to the second photodetector; the first tunable coupler, the second tunable coupler, the third tunable coupler, the first photodetector, and the second photodetector are all connected to the control unit, wherein the switching states of the sixth port and the seventh port are controlled by the control unit, so that the photonic integrated circuit is configured as a lidar or an optical fiber sensor.

[0006] The photonic integrated circuit provided in this embodiment can be configured into different types of sensors through the cooperation between the reflective optical amplifier, the wavelength selective mirror, the first tunable coupler, the second tunable coupler, the third tunable coupler, the first photodetector, and the second photodetector through a control unit. In applications such as robots that require multiple sensors, multiple sensors can be controlled using the same control unit, which not only reduces the production cost, power consumption, weight, and size of the sensors, but also simplifies the control and wiring within the robot, reducing the cost, power consumption, weight, and size of the robot.

[0007] In an optional embodiment, when the photonic integrated circuit is configured as a lidar, the sixth port and the seventh port are both in a conducting state; the second tunable coupler is used to perform splitting processing on the detection light signal, a portion of the detection light signal enters the third tunable coupler from the connection channel between the sixth port and the eighth port to form a reference light signal, and another portion of the detection light signal is emitted from the seventh port to the target object, and the echo light signal is the detection light signal reflected from the target object; the third tunable coupler is used to mix the reference light signal and the echo light signal to obtain a mixed light signal, and output it to a balanced photodetector formed by the first photodetector and the second photodetector.

[0008] In an optional embodiment, the fiber optic sensor is an optical frequency domain reflectometer. When the photonic integrated circuit is configured as an optical frequency domain reflectometer, the sixth port and the seventh port are both in a conducting state, and the seventh port is connected to the first optical fiber. The second tunable coupler is used to perform splitting processing on the detection light signal. A portion of the detection light signal enters the third tunable coupler from the connection channel between the sixth port and the eighth port to form a reference light signal, and another portion of the detection light signal is transmitted from the seventh port to the first optical fiber. The echo light signal is the detection light signal returning from the first optical fiber. The third tunable coupler is used to perform mixing processing on the reference light signal and the echo light signal to obtain a mixed light signal, and output it to a balanced photodetector formed by the first photodetector and the second photodetector.

[0009] In an optional embodiment, the optical fiber sensor is a fiber Bragg grating sensor. When the photonic integrated circuit is configured as a fiber Bragg grating sensor, the sixth port is in an off state and the seventh port is in an on state. The seventh port is connected to the second optical fiber, and the second optical fiber is etched with a Bragg grating. The second tunable coupler transmits the detection light signal to the second optical fiber through the seventh port, and the echo light signal is the detection light signal reflected from the second optical fiber. The third tunable coupler transmits the detection light signal to the second photodetector through the eleventh port.

[0010] In an optional embodiment, the fiber optic sensor is a fiber optic distributed acoustic sensor. When the photonic integrated circuit is configured as a fiber optic distributed acoustic sensor, the sixth port and the seventh port are both in a conducting state, the seventh port is connected to one end of the erbium-doped optical amplifier, the other end of the erbium-doped optical amplifier is connected to the fifteenth port of the circulator, the sixteenth port of the circulator is connected to the third optical fiber, and the seventeenth port of the circulator is connected to the ninth port; the second tunable coupler is used to perform optical splitting processing on the detection light signal, a portion of the detection light signal enters the third tunable coupler from the connection channel between the sixth port and the eighth port to form a reference light signal, and another portion of the detection light signal is transmitted from the seventh port to the erbium-doped optical amplifier and the third optical fiber, and the echo light signal is the detection light signal returned from the third optical fiber; the third tunable coupler is used to perform mixing processing on the reference light signal and the echo light signal to obtain a mixed light signal, and output it to a balanced photodetector formed by the first photodetector and the second photodetector.

[0011] In an optional embodiment, the optical fiber sensor is a spectrum analyzer. When the photonic integrated circuit is configured as a spectrum analyzer, the sixth port is in an on state, the seventh port is in an off state, and the ninth port is connected to the light source under test; the second tunable coupler transmits the detection light signal to the third tunable coupler through the sixth port to form a reference light signal, and the echo light signal is a light signal obtained from the light source under test; the third tunable coupler is used to mix the reference light signal and the echo light signal to obtain a mixed light signal, and output it to a balanced photodetector formed by the first photodetector and the second photodetector.

[0012] In an optional embodiment, the photonic integrated circuit further includes a phase modulator, and the first port is connected in series with the phase modulator and then connected to the reflective optical amplifier.

[0013] In an optional embodiment, the photonic integrated circuit further includes a fourth tunable coupler and a wavelength monitor; the fourth tunable coupler includes a twelfth port, a thirteenth port and a fourteenth port, the twelfth port is connected to the second port, the thirteenth port is connected to the fifth port, and the fourteenth port is connected to the wavelength monitor.

[0014] In this embodiment, by providing a fourth tunable coupler and a wavelength monitor, the control unit can understand the wavelength of the detection light signal in real time and determine whether the wavelength of the detection light signal has shifted, so as to promptly calibrate the wavelength of the laser after the shift, thereby ensuring the signal-to-noise ratio and measurement accuracy of the sensing signal.

[0015] In an optional embodiment, the wavelength selective mirror, the first tunable coupler, the second tunable coupler, and the third tunable coupler are integrated on the same semiconductor substrate.

[0016] In a second aspect, the present invention provides a robot, comprising a control unit and multiple photonic integrated circuits according to the first aspect or any corresponding embodiment thereof, wherein the control unit is connected to a first tunable coupler, a second tunable coupler, a third tunable coupler, a first photodetector, and a second photodetector of each photonic integrated circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 is a schematic structural diagram of a photonic integrated circuit according to an embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of an optical path when a photonic integrated circuit according to an embodiment of the present invention is configured as a laser radar;

[0020] Figure 3 is a schematic diagram of an optical path of a photonic integrated circuit configured for optical frequency domain reflectometry according to an embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of an optical path when a photonic integrated circuit according to an embodiment of the present invention is configured as a fiber Bragg grating sensor;

[0022] Figure 5 is a schematic diagram of an optical path when a photonic integrated circuit according to an embodiment of the present invention is configured as a fiber distributed acoustic sensor;

[0023] Figure 6 is a schematic diagram of an optical path when the photonic integrated circuit according to an embodiment of the present invention is configured as an optical spectrum analyzer;

[0024] Figure 7 3 is a schematic structural diagram of a photonic integrated circuit according to an embodiment of the present invention.

[0025] Reference numerals: 100, photonic integrated circuit; 101, reflective optical amplifier; 102, wavelength selective mirror; 1021, input end of wavelength selective mirror; 1022, output end of wavelength selective mirror; 103, first tunable coupler; 10931, first port; 1032, second port; 1033, third port; 1034, fourth port; 104104, second tunable coupler; 10941, fifth port; 1042, sixth port; 1043, seventh port; 105105, third tunable coupler; 10951, eighth port ; 1052, ninth port; 1053, tenth port; 1054, eleventh port; 106, first photodetector; 107, second photodetector; 108, phase modulator; 109, fourth tunable coupler; 1091, twelfth port; 1092, thirteenth port; 1093, fourteenth port; 110, wavelength monitor; 200, control unit; 300, target object; 400, first optical fiber; 500, second optical fiber; 600, erbium-doped optical amplifier; 700, third optical fiber; 800, circulator; 900, light source under test. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. According to the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention.

[0027] The present invention provides a photonic integrated circuit (PIC) and a robot. The PIC can be configured as a laser radar or fiber optic sensor through a control unit, allowing the PIC to perform a variety of different sensing functions. This allows the robot to control multiple sensors with a single control unit, simplifying control and wiring and reducing cost, power consumption, and size.

[0028] The structure of the photonic integrated circuit provided by the present invention is described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the photonic integrated circuit 100 provided by the present invention includes a reflective optical amplifier 101, a wavelength selective mirror 102, a first tunable coupler 103, a second tunable coupler 104, a third tunable coupler 105, a first photodetector 106 and a second photodetector 107.

[0030] The first tunable coupler 103 includes a first port 1031 , a second port 1032 , a third port 1033 and a fourth port 1034 ; the second tunable coupler 104 includes a fifth port 1041 , a sixth port 1042 and a seventh port 1043 ; and the third tunable coupler 105 includes an eighth port 1051 , a ninth port 1052 , a tenth port 1053 and an eleventh port 1054 .

[0031] A tunable coupler is an optical device that can change the optical signal coupling ratio through external adjustments (such as voltage, temperature, mechanical displacement, etc.). A tunable coupler distributes optical power to different ports in the transmission optical path as needed, and the coupling ratio can be dynamically adjusted. A tunable coupler can be composed of two directional couplers and at least one phase shifter. A directional coupler is an optical device that couples an optical signal from the main transmission path (input port) to another path (coupling port) at a fixed ratio and provides reverse isolation (the signal input from the coupling port hardly returns to the main path). The coupling ratio of a directional coupler is not adjustable.

[0032] like Figure 1 As shown, the first port 1031 is connected to the reflective semiconductor optical amplifier (RSOA) 101, the second port 1032 is connected to the fifth port 1041, the third port 1033 is connected to the input end 1021 of the wavelength selective mirror 102, and the fourth port 1034 is connected to the output end 1022 of the wavelength selective mirror 102. The reflective optical amplifier 101 is used to generate an initial optical signal, and the wavelength selective mirror 102 is used to reflect the initial optical signal of the target wavelength to form a detection optical signal that is output from the second port 1032. The initial optical signal can be a laser signal, and the detection optical signal is the initial optical signal of the target wavelength reflected from the wavelength selective mirror 102.

[0033] The sixth port 1042 is connected to the eighth port 1051 , the ninth port 1052 is used to receive the echo optical signal, the tenth port 1053 is connected to the first photodetector 106 , and the eleventh port 1054 is connected to the second photodetector 107 .

[0034] The first tunable coupler 103, the second tunable coupler 104, the third tunable coupler 105, the first photodetector 106, and the second photodetector 107 are all connected to the control unit 200, wherein the switching states of the sixth port 1042 and the seventh port 1043 are controlled by the control unit 200, so that the photonic integrated circuit 100 is configured as a laser radar (LiDAR) or a fiber optic sensor.

[0035] Specifically, the reflective optical amplifier 101, wavelength selective mirror 102, and first tunable coupler 103 in the photonic integrated circuit constitute a tunable laser. The reflective optical amplifier 101 serves as the gain section. The initial optical signal generated by the current injected into the gain section enters the first tunable coupler 103 through the first port 1031 and then enters the wavelength selective mirror 102 through the third port 1033. The wavelength selective mirror 102 filters the initial optical signal and reflects the initial optical signal of a specific wavelength (i.e., the target wavelength). The reflected initial optical signal of the target wavelength enters the first tunable coupler 103 through the waveguide between the output port 1022 of the wavelength selective mirror 102 and the fourth port 1034. A portion of the initial optical signal returns to the gain section, while the remaining portion is output from the second port 1032. The optical signal output from the second port 1032 is the detection optical signal.

[0036] The initial optical signal generated by the current injected into the gain section is reflected by the wavelength selective mirror 102, with a portion returning to the gain section. The wavelength selective mirror 102 at one end of the gain section and the reflector at the other end of the gain section together form a laser resonant cavity. The output light of the tunable laser (i.e., the detection light signal) is output by the first tunable coupler 103 and transmitted to the second tunable coupler 104. The reflective semiconductor optical amplifier, as a gain chip, provides a wide gain spectrum, and the wavelength selective mirror is used to filter the wavelength of the signal reflected by it.

[0037] Exemplarily, the wavelength selective mirror 102 can be composed of two microring resonators. The resonance of the microring resonator can be controlled by a heater placed on the microring resonator. Utilizing the vernier effect, the two microring resonators can act as wavelength filters and be tuned over a wide wavelength range. A reflective semiconductor optical amplifier includes an active region and a reflector. The active region generates stimulated emission gain through current injection. The reflectivity of the reflector end face is typically 30% to 90%, which determines the number of round trips of the optical signal within the active region. The greater the number of reflections, the greater the gain.

[0038] The directional coupler and phase shifter included in the second tunable coupler 104 can form a Mach–Zehnder Interferometer (MZI). The control unit 200 controls the power distribution (splitting ratio) of the output end (sixth port 1042 and seventh port 1043) by adjusting the phase difference between the two arms, and adjusts the switching state (on state or off state) of the sixth port 1042 and the seventh port 1043, thereby configuring the photonic integrated circuit as a lidar or a fiber optic sensor.

[0039] Exemplarily, the phase shifter can be a thermo-optic phase shifter or an electro-optic phase shifter. When the phase shifter is a thermo-optic phase shifter (including a heating electrode), the control unit 200 can utilize the thermo-optic effect of the material (temperature change, refractive index change) to energize the heating electrode, causing the local temperature change, changing the waveguide refractive index, and thereby controlling the power distribution at the output end. When the phase shifter is an electro-optic phase shifter (including electrodes), the control unit 200 can rely on the electro-optic effect of the material (applying voltage, the refractive index changes with the electric field) to apply voltage to the electrode, change the waveguide refractive index, and control the power distribution at the output end. The number of phase shifters can be one or more, and the phase shifter can be set on only one arm of the directional coupler, or phase shifters can be set on both arms.

[0040] It should be understood that the control unit 200 may also configure the power distribution ratio of the first tunable coupler 103 and the third tunable coupler 105 by controlling the phase shifter.

[0041] The types of sensors formed by the photonic integrated circuits are different, and the functions of the second tunable coupler 104 and the third tunable coupler 105 are different. The functions of the second tunable coupler 104 and the third tunable coupler 105 are described below in conjunction with specific sensor types.

[0042] The first photodetector 106 and the second photodetector 107 can convert the optical signal transmitted by the third tunable coupler 105 into an electrical signal, and transmit the electrical signal to the control unit 200, so that the control unit 200 can parse and determine the information (such as distance, speed and temperature) detected by the sensor formed by the photonic integrated circuit.

[0043] It should be understood that the photonic integrated circuit can also be divided into a transmitting (TX) unit and a receiving (RX) unit. The transmitting unit may include a reflective optical amplifier 101, a wavelength selective mirror 102, a first tunable coupler 103 and a second tunable coupler 104, and the receiving unit may include a third tunable coupler 105, a first photodetector 106 and a second photodetector 107.

[0044] The photonic integrated circuit provided in this embodiment can be configured into different types of sensors through the cooperation between the reflective optical amplifier 101, the wavelength selective mirror 102, the first tunable coupler 103, the second tunable coupler 104, the third tunable coupler 105, the first photodetector 106, and the second photodetector 107 via a control unit. In applications such as robots that require multiple sensors, multiple sensors can be controlled using the same control unit, which not only reduces the production cost, power consumption, weight, and size of the sensors, but also simplifies the control and wiring within the robot, reducing the cost, power consumption, weight, and size of the robot.

[0045] Exemplarily, the optical fiber sensor may be an optical frequency domain reflectometer (OFDR), a fiber Bragg grating (FBG) sensor, a fiber distributed acoustic sensor (DAS), or an optical spectrum analyzer (OSA).

[0046] The optical path of a photonic integrated circuit is described below using the examples of a photonic integrated circuit configured as a lidar, an optical frequency domain reflectometer, a fiber Bragg grating sensor, a fiber distributed acoustic sensor, and a spectrum analyzer.

[0047] For example, Figure 2 As shown, when the photonic integrated circuit 100 is configured as a laser radar, the sixth port 1042 and the seventh port 1043 are both in a conducting state.

[0048] The second tunable coupler 104 is used to perform optical splitting processing on the detection light signal. A portion of the detection light signal enters the third tunable coupler 105 from the connection channel (waveguide) between the sixth port 1042 and the eighth port 1051 to form a reference light signal (Local Oscillator, LO). The other portion of the detection light signal is emitted from the seventh port 1043 to the target object 300. At this time, the echo light signal is the detection light signal reflected from the target object 300.

[0049] The third tunable coupler 105 is a coherent receiver for mixing the reference optical signal and the echo optical signal to obtain a mixed optical signal, and output the mixed optical signal to a balanced photodetector (BPD) formed by the first photodetector 106 and the second photodetector 107 .

[0050] After receiving the mixed optical signal, the balanced photodetector is used to convert the mixed optical signal into an analog electrical signal, which is used to determine the distance between the target object 300 and the laser radar formed by the photonic integrated circuit and the moving speed of the target object 300.

[0051] Furthermore, a telescopic lens (not shown in the figure) can be set between the seventh port 1043 and the ninth port 1052 and the target object 300. After the second tunable coupler 104 receives the detection light signal, it performs spectroscopic processing on the detection light signal. A portion of the light enters the third tunable coupler 105 as a reference light signal (local oscillator light), and the remaining light is coupled to the target object 300 through the telescopic lens. The light reflected from the target object 300 is collected by the telescopic lens and mixed with the reference light signal through the third tunable coupler 105.

[0052] Specifically, the time difference between the reference light signal and the echo light signal generates a beat signal. The intermediate frequency of the beat signal is used to determine the distance from the laser radar to the target object. The calculation formula can be shown as formula (1):

[0053]

[0054] In formula (1), D1 represents the distance between the laser radar and the stationary target object, c represents the speed of light in vacuum, and f b represents the beat signal frequency, and γ represents the laser frequency scanning speed.

[0055] When the target object is in motion, two different beat signal frequencies are generated due to Doppler shift. Based on the two beat signal frequencies, formulas (2) and (3), the distance between the target object and the lidar and the moving speed of the target object can be determined:

[0056]

[0057]

[0058] In formula (2), D2 represents the distance between the laser radar and the moving target object, f b1 and f b2 Indicates two different beat signal frequencies. In formula (3), f0 represents the frequency of the reference optical signal.

[0059] In this embodiment, after providing the telescopic lens, by adjusting the lens spacing, the beam diameter of the detection light signal emitted from the seventh port 1043 can be expanded, and the divergence angle can be reduced, so that the detection light can illuminate the target object more accurately. The telescopic lens can also reduce the beam diameter of the detection light signal reflected from the target object to converge the echo light signal to the ninth port 1052, thereby improving the collection efficiency.

[0060] Exemplarily, the laser radar can be a linear frequency modulated continuous wave (FMCW) laser radar, and the detection light signal can be linearly chirped by modulating the current injected into the gain part. The detection light signal can also be linearly chirped by the actuator (such as an electrothermal element, an electro-optical element or a piezoelectric element) of the modulation ring and the phase part.

[0061] Linear chirp refers to the phenomenon that the frequency of light changes linearly with time. Chirped lasers whose emission frequency changes linearly with time can avoid the near-field blind spots caused by the time difference between transmission and reception in pulse radar. Moreover, the larger the chirp bandwidth (such as 100GHz), the higher the distance resolution.

[0062] For example, Figure 3 As shown, when the photonic integrated circuit is configured as an optical frequency domain reflectometer, the sixth port and the seventh port are both in a conducting state, and the seventh port is connected to the first optical fiber 400 .

[0063] The second tunable coupler 104 is used to perform optical splitting processing on the detection light signal. A portion of the detection light signal enters the third tunable coupler 105 from the connection channel between the sixth port 1042 and the eighth port 1051 to form a reference light signal. The other portion of the detection light signal is transmitted from the seventh port 1043 to the first optical fiber 400. At this time, the echo light signal is the detection light signal returning from the first optical fiber 400.

[0064] The third tunable coupler 105 is used to perform mixing processing on the reference optical signal and the echo optical signal to obtain a mixed optical signal, and output the mixed optical signal to a balanced photodetector formed by the first photodetector 106 and the second photodetector 107 .

[0065] Specifically, after the detection light signal output from the seventh port 1043 enters the first optical fiber (the optical fiber under test), Rayleigh scattered light (uniformly distributed) and Fresnel reflected light (strong reflection at the end face or defect) are generated along the way. The scattered / reflected light (i.e., the echo light signal) returned from the first optical fiber 400 enters the third tunable coupler 105 from the ninth port 1052. The echo light signal and the reference light signal undergo beat frequency interference in the third tunable coupler 105, generating an interference signal that varies with frequency.

[0066] The working principle of optical frequency domain reflectometry is based on optical frequency scanning interferometry and Rayleigh scattering / Fresnel reflection principles. By analyzing the interference characteristics of optical signals of different frequencies in the optical fiber, it can achieve high-precision measurement of fiber loss, reflection point position and physical quantities along the optical fiber. It is suitable for locating small strains, temperature gradients or defects (such as fiber Bragg grating inscription monitoring).

[0067] It should be understood that the working principles of optical frequency domain reflectometer and lidar are similar. The main difference is that the sensing medium is optical fiber, and the way in which the photonic integrated circuit is configured as an optical frequency domain reflectometer is basically the same as the way in which the photonic integrated circuit is configured as a lidar.

[0068] For example, Figure 4 As shown, when the photonic integrated circuit is configured as a fiber Bragg grating sensor, the sixth port is in an off state, the seventh port is in an on state, and the seventh port is connected to the second optical fiber 500 etched with a Bragg grating.

[0069] The second tunable coupler 104 transmits the detection light signal to the second optical fiber 500 through the seventh port 1043 . At this time, the echo light signal is the detection light signal reflected from the second optical fiber 500 . The third tunable coupler 105 transmits the echo light signal to the second photodetector 107 through the eleventh port 1054 .

[0070] Specifically, the fiber Bragg grating sensor does not require coherent detection. Therefore, the second tunable coupler 104 does not need to perform spectroscopic processing on the detection light signal to generate a reference light signal. The second tunable coupler 104 can directly transmit the detection light signal to the second optical fiber 500. The detection light signal (i.e., the echo light signal) reflected from the second optical fiber 500 can be guided to the ninth port 1052 through the circulator.

[0071] The working principle of the fiber Bragg grating sensor is based on the wavelength-selective reflection characteristics of the fiber Bragg grating, and physical quantity measurement is achieved by monitoring the wavelength shift of the reflected light. Specifically, physical quantity measurement (such as temperature, strain, etc.) is achieved by scanning the laser wavelength and detecting the echo light signal received by the third tunable coupler 105. During the scanning process, the response of the Bragg grating is recorded and the Bragg wavelength is determined. The Bragg reflection wavelength of the light reflected by the Bragg grating can be expressed as formula (4):

[0072] λ B =2n eff Λ (4)

[0073] In formula (4), λ B represents the Bragg reflection wavelength, n eff represents the effective refractive index of the second optical fiber, and Λ represents the period of the Bragg grating. eff and Λ are sensitive to temperature changes and strain changes, so the change in the Bragg reflection wavelength is used to determine the change in temperature or strain.

[0074] For example, Figure 5As shown, when the photonic integrated circuit is configured as a fiber distributed acoustic sensor, the sixth port 1042 and the seventh port 1043 are both in a conducting state. The seventh port is connected to one end of the erbium-doped optical fiber amplifier (EDFA) 600, the other end of the EDFA 600 is connected to the fifteenth port of the circulator 800, the sixteenth port of the circulator 800 is connected to the third optical fiber 700, and the seventeenth port of the circulator 800 is connected to the ninth port 1052. In other words, the circulator 800 includes three ports: the first port is connected in series with the EDFA and then to the seventh port; the second port is connected to the third optical fiber; and the third port is connected to the ninth port.

[0075] The second tunable coupler 104 is configured to perform optical splitting on the detection light signal. A portion of the detection light signal enters the third tunable coupler 105 through the connection channel between the sixth port 1042 and the eighth port 1051 to form a reference light signal. The remaining portion of the detection light signal is transmitted through the seventh port 1043 to the erbium-doped optical amplifier 600 and the third optical fiber 700. The echo light signal is the detection light signal returned from the third optical fiber 700. The third tunable coupler 105 is configured to perform frequency mixing on the reference light signal and the echo light signal to generate a mixed light signal, which is then output to a balanced photodetector formed by the first and second photodetectors.

[0076] The operating principle of fiber-optic distributed acoustic sensors (DASs) is based on measuring scattering caused by refractive index inhomogeneities formed during the optical fiber manufacturing process. When the scattering is elastic (such as Rayleigh scattering), it is used for acoustic sensing in DASs. When the scattering is inelastic (such as Raman scattering), it is used for temperature sensing in DTSs.

[0077] Specifically, after receiving the detection light signal, the second tunable coupler 104 performs optical splitting processing. A portion of the detection light signal enters the third tunable coupler 105 to form a reference light signal, and the other portion enters the erbium-doped optical amplifier 600 through the seventh port 1043, where it is pre-amplified by the erbium-doped optical amplifier 600 and sent to the third optical fiber 700 through the circulator 800. The detection light signal scattered back from the third optical fiber 700 is collected into the third optical fiber 700 through another channel of the circulator. The detection light signal is amplified and filtered to remove amplified spontaneous emission (ASE) noise before entering the ninth port 1052.

[0078] The tunable laser composed of the reflective optical amplifier 101, wavelength selective mirror 102, and first tunable coupler 103 can be a narrow-linewidth laser. The detection light signal can be pulsed by modulating the current injected into the gain section. The detection light signal can also be pulsed by modulating the drivers on the ring and phase section. A narrow-linewidth laser is one with an extremely narrow output laser spectral linewidth (typically less than 1 MHz). The advantages of narrow-linewidth lasers include high frequency stability, low phase noise, and a long coherence length.

[0079] When the third optical fiber is affected by external factors, the position of the scattering point at the interference point changes, generating different scattered signals, enabling real-time monitoring and location of vibration signals. The configuration of a photonic integrated circuit as a fiber-optic distributed acoustic sensor is similar to that of a photonic integrated circuit as a lidar.

[0080] For example, Figure 6 As shown, when the photonic integrated circuit is configured as a spectrum analyzer, the sixth port 1042 is in an on state, the seventh port 1043 is in an off state, and the ninth port 1052 is connected to the light source 900 under test.

[0081] Second tunable coupler 104 transmits the detection optical signal to third tunable coupler 105 via sixth port 1042. In this case, the echo optical signal is an optical signal obtained from light source 900 under test. Third tunable coupler 105 is configured to mix the reference optical signal and the echo optical signal to obtain a mixed optical signal, which is then output to a balanced photodetector formed by first photodetector 106 and second photodetector 107.

[0082] The working principle of a spectrum analyzer is to decompose composite light into monochromatic light of different wavelengths through spectroscopy and measure the power (intensity) of each wavelength to analyze the spectral characteristics. When configured as a spectrum analyzer, a photonic integrated circuit can detect the spectrum of the measured light source.

[0083] Specifically, after the second tunable coupler 104 receives the detection light signal, it transmits it entirely to the third tunable coupler 105. At this time, the detection light signal is entirely used as a reference light signal. In the third tunable coupler 105, the reference light signal is mixed with the echo light signal from the measured light source, and a beat frequency signal is generated in the balanced photodetector. The beat frequency signal is further filtered using a bandpass filter and analyzed to generate the spectrum of the measured light source.

[0084] Exemplarily, the wavelength selective mirror 102, the first tunable coupler 103, the second tunable coupler 104 and the third tunable coupler 105 can be integrated on the same semiconductor substrate (such as a silicon substrate). The passive structures such as the wavelength selective mirror 102, the first tunable coupler 103, the second tunable coupler 104 and the third tunable coupler 105 can be made of materials such as silicon nitride (SiN), silicon on insulator (SOI) or thin film lithium niobate (TFLN), and the active structures such as the reflective optical amplifier 101, the first photodetector 106 and the second photodetector 107 can be made of materials such as indium phosphide (InP) or gallium arsenide (GaAs).

[0085] The control unit 200 can connect the first tunable coupler 103, the second tunable coupler 104, the third tunable coupler 105, the first photodetector 106, and the second photodetector 107 via a printed circuit board (PCB). The control unit 200 can determine the configuration type of the photonic integrated circuit (lidar or fiber optic sensor) based on user requirements.

[0086] In some embodiments, as Figure 7 As shown, the photonic integrated circuit 100 further includes a phase modulator 108. The first port 1031 is connected in series to the phase modulator 108 and then to the reflective optical amplifier 101. The phase modulator 108 is used to adjust the phase of the laser signal to match the phase of the laser cavity mode.

[0087] Alternatively, as Figure 7 As shown, the photonic integrated circuit 100 further includes a fourth tunable coupler 109 and a wavelength monitor 110 .

[0088] The fourth tunable coupler 109 includes a twelfth port 1091, a thirteenth port 1092, and a fourteenth port 1093. The twelfth port 1091 is connected to the second port 1032, the thirteenth port 1092 is connected to the fifth port 1041, and the fourteenth port 1093 is connected to the wavelength monitor 110. The wavelength monitor 110 is used to detect the wavelength of the detection optical signal output by the first tunable coupler 103 in real time.

[0089] Specifically, in this embodiment, after the first tunable coupler 103 outputs the detection light signal, it does not directly enter the second tunable coupler 104, but enters the fourth tunable coupler 109 for optical splitting processing. A portion of the detection light signal is transmitted to the wavelength monitor through the fourteenth port 1093, and the remaining detection light signal enters the second tunable coupler 104 through the waveguide between the thirteenth port 1092 and the fifth port 1041.

[0090] In this embodiment, by providing the fourth tunable coupler 109 and the wavelength monitor 110, the control unit can understand the wavelength of the detection light signal in real time and determine whether the wavelength of the detection light signal has shifted, so as to promptly calibrate the wavelength of the laser after the shift, thereby ensuring the signal-to-noise ratio and measurement accuracy of the sensing signal.

[0091] The present invention further provides a robot comprising a control unit and a plurality of photonic integrated circuits according to any of the above embodiments. The control unit is connected to the first tunable coupler, the second tunable coupler, the third tunable coupler, the first photodetector, and the second photodetector of each photonic integrated circuit.

[0092] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships according to the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0093] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0094] In the description of this specification, the reference terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0095] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0096] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations shall all fall within the scope defined by the present invention.

Claims

1. A photonic integrated circuit, characterized in that: The photonic integrated circuit includes a reflective optical amplifier, a wavelength selective mirror, a first tunable coupler, a second tunable coupler, a third tunable coupler, a first photodetector and a second photodetector; The first tunable coupler includes a first port, a second port, a third port, and a fourth port, the second tunable coupler includes a fifth port, a sixth port, and a seventh port, and the third tunable coupler includes an eighth port, a ninth port, a tenth port, and an eleventh port; The first port is connected to the reflective optical amplifier, the second port is connected to the fifth port, the third port is connected to the input end of the wavelength selective mirror, and the fourth port is connected to the output end of the wavelength selective mirror. The reflective optical amplifier is used to generate an initial optical signal, and the wavelength selective mirror is used to reflect the initial optical signal of the target wavelength to form a detection optical signal and output from the second port. The sixth port is connected to the eighth port, the ninth port is used to receive the echo optical signal, the tenth port is connected to the first photodetector, and the eleventh port is connected to the second photodetector; The first tunable coupler, the second tunable coupler, the third tunable coupler, the first photodetector, and the second photodetector are all connected to a control unit, wherein the switching states of the sixth port and the seventh port are controlled by the control unit so that the photonic integrated circuit is configured as a lidar or a fiber optic sensor.

2. The photonic integrated circuit according to claim 1, wherein: When the photonic integrated circuit is configured as a laser radar, the sixth port and the seventh port are both in a conducting state; The second tunable coupler is used to perform optical splitting processing on the detection light signal, where a portion of the detection light signal enters the third tunable coupler from the connection channel between the sixth port and the eighth port to form a reference light signal, and another portion of the detection light signal is emitted from the seventh port to the target object, and the echo light signal is the detection light signal reflected from the target object; The third tunable coupler is used to perform frequency mixing processing on the reference optical signal and the echo optical signal to obtain a mixed optical signal, and output the mixed optical signal to a balanced photodetector formed by a first photodetector and a second photodetector.

3. The photonic integrated circuit according to claim 1, wherein: The optical fiber sensor is an optical frequency domain reflectometer, and when the photonic integrated circuit is configured as the optical frequency domain reflectometer, the sixth port and the seventh port are both in a conducting state, and the seventh port is connected to the first optical fiber; The second tunable coupler is configured to perform optical splitting processing on the detection light signal, where a portion of the detection light signal enters the third tunable coupler from the connection channel between the sixth port and the eighth port to form a reference light signal, and another portion of the detection light signal is transmitted from the seventh port to the first optical fiber, and the echo light signal is the detection light signal returned from the first optical fiber; The third tunable coupler is used to perform frequency mixing processing on the reference optical signal and the echo optical signal to obtain a mixed optical signal, and output the mixed optical signal to a balanced photodetector formed by a first photodetector and a second photodetector.

4. The photonic integrated circuit according to claim 1, wherein: The optical fiber sensor is a fiber Bragg grating sensor. When the photonic integrated circuit is configured as a fiber Bragg grating sensor, the sixth port is in an off state, the seventh port is in an on state, the seventh port is connected to a second optical fiber, and the second optical fiber is etched with a Bragg grating. The second tunable coupler transmits the detection light signal to the second optical fiber through the seventh port, and the echo light signal is the detection light signal reflected from the second optical fiber; The third tunable coupler transmits light to the second photodetector through the eleventh port.

5. The photonic integrated circuit according to claim 1, wherein: The optical fiber sensor is a fiber distributed acoustic sensor. When the photonic integrated circuit is configured as the fiber distributed acoustic sensor, the sixth port and the seventh port are both in a conducting state, the seventh port is connected to one end of an erbium-doped optical amplifier, the other end of the erbium-doped optical amplifier is connected to the fifteenth port of a circulator, the sixteenth port of the circulator is connected to the third optical fiber, and the seventeenth port of the circulator is connected to the ninth port. The second tunable coupler is used to perform optical splitting processing on the detection light signal, wherein a portion of the detection light signal enters the third tunable coupler from the connection channel between the sixth port and the eighth port to form a reference light signal, and another portion of the detection light signal is transmitted from the seventh port to the erbium-doped optical amplifier and the third optical fiber, and the echo light signal is the detection light signal returned from the third optical fiber; The third tunable coupler is used to perform frequency mixing processing on the reference optical signal and the echo optical signal to obtain a mixed optical signal, and output the mixed optical signal to a balanced photodetector formed by a first photodetector and a second photodetector.

6. The photonic integrated circuit according to claim 1, wherein: The optical fiber sensor is a spectrum analyzer. When the photonic integrated circuit is configured as a spectrum analyzer, the sixth port is in an on state, the seventh port is in an off state, and the ninth port is connected to a light source to be measured; The second tunable coupler transmits the detection optical signal to the third tunable coupler through the sixth port to form a reference optical signal, and the echo optical signal is an optical signal obtained from the light source under test; The third tunable coupler is used to perform frequency mixing processing on the reference optical signal and the echo optical signal to obtain a mixed optical signal, and output the mixed optical signal to a balanced photodetector formed by a first photodetector and a second photodetector.

7. The photonic integrated circuit according to any one of claims 1 to 6, characterized in that: The photonic integrated circuit further includes a phase modulator, and the first port is connected in series with the phase modulator and then connected to the reflective optical amplifier.

8. The photonic integrated circuit according to claim 7, wherein: The photonic integrated circuit further includes a fourth tunable coupler and a wavelength monitor; The fourth tunable coupler includes a twelfth port, a thirteenth port, and a fourteenth port. The twelfth port is connected to the second port, the thirteenth port is connected to the fifth port, and the fourteenth port is connected to the wavelength monitor.

9. The photonic integrated circuit according to any one of claims 1 to 6, characterized in that: The wavelength selective mirror, the first tunable coupler, the second tunable coupler, and the third tunable coupler are integrated on a same semiconductor substrate.

10. A robot, characterized in that: The robot includes a control unit and a plurality of photonic integrated circuits according to any one of claims 1 to 9, wherein the control unit is connected to a first tunable coupler, a second tunable coupler, a third tunable coupler, a first photodetector, and a second photodetector of each photonic integrated circuit.

Images