WO2022062105A1 - 一种阵列式相干测距芯片及其系统 - Google Patents
一种阵列式相干测距芯片及其系统 Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/32—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/491—Details of non-pulse systems
- G01S7/4911—Transmitters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/491—Details of non-pulse systems
- G01S7/4912—Receivers
- G01S7/4913—Circuits for detection, sampling, integration or read-out
- G01S7/4914—Circuits for detection, sampling, integration or read-out of detector arrays, e.g. charge-transfer gates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/32—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
- G01S17/36—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated with phase comparison between the received signal and the contemporaneously transmitted signal
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/491—Details of non-pulse systems
- G01S7/4912—Receivers
- G01S7/4917—Receivers superposing optical signals in a photodetector, e.g. optical heterodyne detection
Definitions
- the present application relates to the technical field of lidar, in particular to an array type coherent ranging chip and a system thereof.
- LiDAR Laser detection and ranging, LiDAR
- LiDAR is a long-range sensing technology, which has a wide range of irreplaceable applications in autonomous driving, virtual/augmented reality, optical communication and other fields. Irradiate the measured target and measure the return signal to complete the detection of the distance of the measured target.
- the first is the time-of-flight method, which determines the distance of the object by detecting the time delay of the transmitted and received optical pulses.
- the disadvantage of this method is that the ranging distance is short. And can only achieve single-point measurement and the anti-interference ability is very weak; the second is coherent detection, according to the different laser modulation methods, the more common schemes are: frequency modulated continuous wave (FMCW) and chirp amplitude modulation (chirped amplitude modulated, CAM) and so on.
- FMCW frequency modulated continuous wave
- CAM chirp amplitude modulation
- the processing methods generally include: flash, MEMS micromirror and optical phase.
- OPA Optical Phased Array
- Flash solutions do not contain mechanical moving or rotating structures, so the lidar has the advantages of high reliability and compact structure.
- Flash realizes simultaneous emission and reception of multiple angles in the field of view based on a wide emission angle light source and a detector array, and obtains distance information based on Time of Flight (TOF).
- TOF Time of Flight
- the total output power of the light source is limited by the safety power of the human eye. Since the light source is emitted from multiple angles at the same time, the emission power per unit angle is limited, and the intensity of the light signal reflected by the target is inversely proportional to the target distance.
- the time-of-flight detector The array can only identify signals above the noise limit, limiting detection distance.
- the Flash solution based on the time-of-flight method is easily affected by ambient light.
- the embodiments of the present application provide an array-type coherent ranging chip and a system thereof to solve the technical problems of limited ranging and poor anti-interference strength of lidar in the prior art.
- a first aspect of the embodiments of the present application provides an array type coherent ranging chip, the chip includes: a modulated light source unit, an on-chip transmitting unit, and a receiving array, the modulated light source unit is configured to generate a modulated light beam, and divide the modulated light beam into Signal light and reference light output; the on-chip emitting unit is used to irradiate the signal light to the target object at a preset divergence angle and reflect to form multi-angle signal light; the receiving array is used to receive the reference light and all The multi-angle signal light is obtained, and the reference light and the signal light of each angle are respectively converted and detected to obtain a plurality of ranging signals.
- the receiving array includes: a plurality of receiving units, each receiving unit includes a diffractive structure, a light combining component and a detector, the diffractive structure receives the reflected light of the corresponding angle, and guides the reflected light of the corresponding angle to the the input end of the optical combination component; the optical combination component receives the reference light and the reflected light of the corresponding angle, combines the reference light and the reflected light of the corresponding angle into a composite signal, and separates the composite signal into the first a detection signal and a second detection signal; the detector receives the first detection signal and the second detection signal, converts the first detection signal and the second detection signal into electrical signals, and converts the electrical The difference value output of the signals obtains the ranging signal.
- the receiving array further includes: a first beam splitting area, the first beam splitting area includes a plurality of beam splitting units, the first beam splitting area receives the reference light, and processes the reference light After splitting, the beams are respectively transmitted to the light combining components of each receiving unit.
- the working wavelength of the modulated light source unit includes a visible light band and a near-infrared band.
- the diffractive structure includes a one-dimensional or two-dimensional diffractive optical element;
- the light combining component includes a diffractive optical element, a diffraction grating, a metasurface, a Y branch, a multimode interference coupler, a directional coupler, and a star coupling.
- the detector includes any one of an avalanche photodiode, a photomultiplier tube, or a PIN diode.
- the modulated light source unit includes: a modulation unit and a beam splitting unit, the modulation unit includes a light source and a signal generator, and the modulation mode of the light source is external modulation or internal modulation, when amplitude modulation is realized based on the principle of external modulation.
- the modulation unit further includes an intensity modulator; when based on the principle of internal modulation, the modulation unit does not include an intensity modulator;
- the beam splitting unit includes a Y branch, a star coupler, a multimode interference coupler, a directional Any of a coupler, a polarizing beam splitter, a partially diffractive partially transmissive waveguide grating structure.
- the on-chip emitting unit includes: an on-chip beam expander structure and a diffraction structure, the on-chip beam expander structure shapes the signal light and outputs it; the diffraction structure shapes the shaped signal light at a preset divergence angle. It is reflected on the target object to form multi-angle signal light.
- the on-chip beam-expanding structure includes an adiabatic inverted tapered waveguide, a slab waveguide concave mirror, a slab waveguide lens based on the thickness gradient of the waveguide layer, a graded refractive index slab waveguide lens based on a micro-nano structure, and a cascaded beam splitter. and any one of a star coupler; the diffractive structure includes a waveguide diffraction grating array or a slab waveguide grating.
- the on-chip emitting unit includes an optical phased array
- the optical phased array includes a second beam splitting area, a phased area, and an exit unit, and the second beam splitting area is used to transmit the signal light.
- the phase control area After beam splitting, output to the phase control area; the phase control area is used to phase modulate the signal light after the beam split; the output unit is used to output the phase modulated signal light, so that the two-dimensional signal light The signal light strikes the target object.
- the on-chip emission unit realizes scanning of signal light in different emission directions under the control of an external scanning device.
- the optical element and the electrical element on the chip are integrated on a single chip or on two chips, and when integrated on two chips, the two chips are connected by an optical signal or an electrical signal.
- the array type coherent ranging chip further includes: any one of a rectangular waveguide, a ridge waveguide and a slit waveguide, which is used to transmit the optical signal on the chip; when the working wavelength is in the visible band, using The chip is integrated based on a hybrid integration platform of silicon nitride and silicon, and silicon nitride is used as the waveguide material; when the operating wavelength is in the infrared band, the chip is integrated based on a silicon-on-insulator platform.
- a second aspect of the embodiments of the present application provides an array-type coherent ranging system, the system including: a signal processing unit and the array-type coherent ranging chip according to any one of the first aspect and the first aspect of the embodiments of the present application,
- the signal processing unit receives the ranging signal output by the array type coherent ranging chip, and obtains the distance of the target object through spectrum analysis and calculation.
- the array type coherent ranging chip realized by using a chip, has a compact structure, high reliability, and reduces the cost of ranging;
- the generated ranging signal is proportional to the product of the amplitude of the reference light and the signal light. Selecting the appropriate reference power can realize the signal amplitude control and expand the ranging range, and components different from the wavelength of the light source will not be able to form a stable interference signal, so it has The effect of anti-interference of ambient light; in addition, the multi-angle reflected light is received by the receiving array, which can make multi-pixel data parallel processing, compared with scanning coherent radar, the number of acquisition points per unit time is greatly increased.
- the array-type coherent ranging system provided by the embodiment of the present application can measure the distance of the target object, has a simple structure, low cost, can realize miniaturization and chipization, and is easier to integrate.
- the ranging system adopts a coherent detection method, Not only can it amplify the signal, but the components with different wavelengths from the light source will not be able to form a stable interference signal, which has the effect of resisting environmental interference.
- 1 is a structural block diagram of an array type coherent ranging chip in an embodiment of the application
- FIG. 2 is a structural block diagram of an array-type coherent ranging chip in another embodiment of the present application.
- FIG. 3 is a structural block diagram of a receiving unit of an array type coherent ranging chip in an embodiment of the application;
- FIG. 4 is a structural block diagram of an array-type coherent ranging system in an embodiment of the present application.
- FIG. 5 is a schematic diagram of modulation of an array type coherent ranging chip in an embodiment of the present application
- FIG. 6 is a structural block diagram of a coherent ranging chip in another embodiment of the present application.
- FIG. 7 is a structural block diagram of a coherent ranging chip in another embodiment of the present application.
- the terms “installed”, “connected” and “connected” should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection connection, or integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two components, which can be a wireless connection or a wired connection connect.
- installed should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection connection, or integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two components, which can be a wireless connection or a wired connection connect.
- the chip includes: a modulated light source unit 101 , an on-chip emitting unit 102 and a receiving array 103 .
- the modulated light source unit 101 is used to generate a modulated light beam, and The modulated light beam is divided into signal light and reference light output;
- the on-chip emission unit 102 is used to irradiate the signal light on the target object with a preset divergence angle and reflect to form multi-angle signal light;
- the receiving array 103 is used to receive the reference light and the multi-angle signal light.
- the reference light and the signal light of each angle are respectively converted and detected to obtain a plurality of ranging signals.
- the array type coherent ranging chip realized by using a chip, has a compact structure, high reliability, and reduces the cost of ranging;
- the generated ranging signal is proportional to the product of the amplitude of the reference light and the signal light. Selecting the appropriate reference power can realize the signal amplitude control and expand the ranging range, and components different from the wavelength of the light source will not be able to form a stable interference signal, so it has The effect of anti-interference of ambient light; in addition, the multi-angle reflected light is received by the receiving array, which can make multi-pixel data parallel processing, compared with scanning coherent radar, the number of acquisition points per unit time is greatly increased.
- the receiving array 103 includes: a plurality of receiving units, each receiving unit includes a diffractive structure 601, a light combining component 602 and a detector 603, and the diffractive structure 601 receives the reflected light, guide the reflected light of the corresponding angle to the input end of the corresponding light combination component 602; the light combination component 602 receives the reference light and the reflected light of the corresponding angle, and combines the reference light and the reflected light of the corresponding angle into a composite signal, and The composite signal is separated into a first detection signal and a second detection signal; the detector 603 receives the first detection signal and the second detection signal, converts the first detection signal and the second detection signal into an electrical signal, and compares the difference between the electrical signals The value output gets the ranging signal.
- the light combining component 602 can combine the incident reference light E Lo and the reflected light of the corresponding angle
- the output forms 4 mixing signals with amplitudes of and
- the first two and the last two respectively form two sets of signals with a difference of 0 degrees and 180 degrees.
- the four signals output by the optical combination component 602 are then received by the detector in the receiving unit; wherein, the two groups of signals with a phase difference of 0° and 180° are respectively detected by the signal circuit of the detector 603 to form a balanced detection. Therefore, the first detection signal and the second detection signal respectively contain two signals, and the two signals in each detection signal respectively enter the two inputs of the balanced detector.
- the detector can convert the incident optical signal into an electrical signal.
- the output is obtained by summing the difference signals of the two sets of signals. signal, so that the effect of phase on the signal can be filtered out.
- the implementations of the light combining component 602 include, but are not limited to, diffractive optical elements, diffraction gratings, metasurfaces, Y branches, multimode interference couplers, directional couplers, star couplers, and polarization beam splitters; diffraction
- the structure 601 includes a one-dimensional or two-dimensional diffractive optical element such as a waveguide diffraction grating array or a slab waveguide grating; the detector 603 is composed of four detection arrays corresponding to the four output signals of the light combining component 602 one-to-one, wherein the detector 603 includes Any of avalanche photodiodes, photomultiplier tubes and PIN diodes.
- the receiving array further includes: a first beam splitting area, the first beam splitting area includes a plurality of beam splitting units, the first beam splitting area receives the reference light, splits the reference light and transmits it to each of the beam splitting units respectively. in the optical combination assembly of the receiving unit. Specifically, since the signal light reflected by the target object includes multi-angle reflected light, the reference light can be uniformly divided into each receiving unit of the receiving array through beam splitting as the intrinsic light.
- the modulated light source unit includes: a modulation unit and a beam splitting unit, the modulation unit includes a light source and a signal generator, and the modulation mode of the light source includes external modulation or internal modulation.
- the modulation unit An intensity modulator is also included; when based on the principle of internal modulation, the modulation unit does not include an intensity modulator.
- the central wavelength range of the light source in the modulated light source unit 101 is 400 nm-3000 nm, including visible light to near-infrared wavelengths.
- the modulated light source unit 101 includes: a light source 202 , a modulator 203 , a signal generator (not shown) and a beam splitting unit 204 .
- various types of waveguides such as rectangular waveguides, ridge waveguides, slit waveguides, etc.
- waveguides can be set on the chip to transmit light beams; when selecting light sources with different wavelength bands, different waveguides can be selected for implementation, such as For the near-infrared band, silicon on insulator (SOI) can be selected, and for the visible light band, silicon nitride can be selected as the waveguide material, and a platform based on hybrid integration of silicon nitride and silicon can be selected.
- SOI silicon on insulator
- the modulation unit modulates the output beam of the light source to generate a beam whose wavelength or amplitude modulation frequency changes with time, and the modulation type includes chirped amplitude modulation (CAM) or frequency modulation continuous wave (FMCW) ) any of them.
- the modulation unit includes, but is not limited to, a Mach-Zehnder interferometer (MZI), a ring resonator interferometer (Ring Resonator), a tunable optical attenuator, and the like.
- the beam splitting unit may include any one of a Y branch, a star coupler, a multi-mode interference coupler, a directional coupler, a polarization beam splitter, and a partially diffractive and partially transmissive waveguide grating structure.
- the on-chip emitting unit includes: an on-chip beam expander structure and a diffraction structure, the on-chip beam expander structure shapes the signal light and outputs it; the diffraction structure irradiates the shaped signal light to the target object at a preset divergence angle for reflection. Multi-angle signal light is formed.
- the on-chip beam expander structure includes adiabatic inverted tapered waveguides, slab waveguide concave mirrors, slab waveguide lenses based on thickness gradients of waveguide layers, graded index slab waveguide lenses based on micro-nano structures, cascaded beam splitters, and star-shaped Any of the couplers;
- the diffractive structure includes a waveguide diffraction grating array or a slab waveguide grating.
- an off-chip scanning device can also be provided outside the chip to scan the signal light output by the on-chip emitting unit, and the off-chip scanning device can be a MEMS micromirror or a transmission/reflection optical phased array (optical phased array, OPA), the off-chip scanning device can realize the scanning of the signal light emission direction, and realize the dynamic sub-field angle ranging.
- OPA optical phased array
- a corresponding guiding structural unit can also be provided to guide the multi-angle reflected light reflected by the target object to the receiving array.
- the guiding structure can be set as a Fourier lens 206, which can focus the reflected signal light of different angles on the corresponding multiple receiving units respectively, so as to realize the corresponding target of each receiving unit.
- a field of view of the object to detect the shape and position of the target object.
- an optical phased array can be directly set in the on-chip emitting unit, the optical phased array includes a second beam splitting area, a phased area and an exit unit, and the second beam splitting area is used to split the signal light into beams. Then output to the phase control area; the phase control area is used to phase-modulate the split signal light; the output unit is used to output the phase-modulated signal light, so that the signal light in two dimensions is irradiated on the target object.
- the signal light split from the beam splitting unit enters the second beam splitting area through the waveguide, and then enters each channel of the phase control area uniformly, and then enters the phase modulator in the phase control area, and passes through each channel in the phase control area.
- the channel's phase modulator controls the phase distribution of each channel individually.
- the deflection of the optical phased array output unit in one direction can be realized by controlling the phase distribution between the channels of the optical phased array; in addition, by using the dispersion characteristics of the phased array output unit, the change of the output wavelength can be achieved by changing the output wavelength. Therefore, the scanning function of the coherent ranging chip in two dimensions can be realized.
- optical phased array by controlling the number of channels and structural parameters of the optical phased array, high-quality beams can be easily achieved and side lobes can be suppressed; and compared with MEMS micromirrors, optical phased arrays can be more easily integrated in ranging on the chip.
- the emitting unit can be implemented with a grating structure.
- the signal light output by the beam splitting unit by controlling the phase modulator and modulating the duty cycle of the emitting unit, the signal light can be deflected in two directions respectively, thereby The scanning of the signal light in two directions is realized.
- An embodiment of the present application provides an array-type coherent ranging system.
- the system includes: a signal processing unit 104 and the array-type coherent ranging chip provided in the above-mentioned embodiments, and the signal processing unit receives the array-type coherent ranging chip. From the ranging signal output by the chip, the distance to the target object is calculated by spectrum analysis.
- the waveform of the output beam of the modulated light source is a triangular wave
- the following relationship is satisfied between the wavelength/amplitude chirp modulation parameters of the coherent ranging chip light source and the target distance R and velocity v:
- c is the speed of light in vacuum
- ⁇ 0 is the vacuum center wavelength
- f Sig is the signal frequency
- B is the wavelength of the light source or the frequency bandwidth of the amplitude chirp modulation
- T 0 is the modulation period
- ⁇ f is the rising edge signal frequency f Sig+ and the falling edge signal The difference between the frequencies f Sig- .
- the array-type coherent ranging system provided by the embodiment of the present application can measure the distance of the target object, has a simple structure, low cost, can realize miniaturization and chipization, and is easier to integrate.
- the ranging system adopts a coherent detection method, Not only can it amplify the signal, but the components with different wavelengths from the light source will not be able to form a stable interference signal, which has the effect of resisting environmental interference.
- FIG. 2 is a schematic structural diagram of an array type coherent ranging chip provided by an embodiment of the present application, which are a modulated light source unit 101, an on-chip transmitting unit 102, and a receiving array 103, respectively.
- the modulated light source unit 101 includes a light source 202, a modulator 203 and beam splitting unit 204; the receiving array 103 includes N receiving units.
- the light beam output by the light source 202 after being modulated by the modulator 203, enters the beam splitting unit 204 and is divided into two parts, one part directly reaches each receiving unit in the receiving array as a reference light; the other part is a signal light, which is output by the on-chip transmitting unit 102 Then, the target object is irradiated with a large divergence angle. After the reflected light is processed by the corresponding guiding structural unit, the reflected signal light of different angles will be received by the N receiving units in the receiving array 103, and each receiving unit corresponds to the target. A field of view of the object.
- an optical component for controlling the intensity of the light beam can be provided on the chip, for example, an optical component for controlling the intensity or frequency of the signal output from the light source, or an optical component for controlling the intensity of the reflected signal from the target object received by the chip.
- the light source 202 can be a laser or a laser array; the central wavelength range of the light source 202 is 400nm-3000nm, including visible light to near-infrared wavelengths; the modulator 203 modulates the output beam of the light source to generate wavelength or amplitude modulation frequency over time
- the modulation type of the changing beam includes any one of Chirped Amplitude Modulation (CAM) or Frequency Modulation Continuous Wave (FMCW), as shown in Figure 5.
- the beam splitting unit 204 separates the modulated light beams as reference light and signal light.
- the modulator 203 includes, but is not limited to, a Mach-Zehnder interferometer (MZI), a ring resonator interferometer (Ring Resonator), a tunable optical attenuator, and the like.
- the beam splitting unit 204 includes, but is not limited to, a Y branch, a star coupler, a multi-mode interference coupler (MMI), a directional coupler, a polarizing beam splitter, a partially diffractive partially transmissive waveguide grating structure, and the like.
- the on-chip emitting unit 102 includes: an on-chip beam expander structure and a diffraction structure. After the on-chip beam expander structure shapes the output signal light, the signal light is irradiated on the target object with a large divergence angle through the diffraction structure to form reflected signal light; the on-chip beam expander
- the structure includes any one of adiabatic inverted tapered waveguide, slab waveguide concave mirror, slab waveguide lens based on thickness gradient of waveguide layer, refractive index graded slab waveguide lens based on micro-nano structure, cascaded beam splitter and star coupler.
- Species; diffractive structures include waveguide diffraction grating arrays or slab waveguide gratings.
- Each receiving element in the receiving array 103 includes a diffractive structure, a light combining component and a detector. Before the reflected signal light enters the receiving array 103, it needs to be processed by the corresponding guiding structural unit, such as the Fourier lens 206, which can focus the reflected signal light of different angles on the corresponding N receiving units respectively, so as to realize each Each receiving unit corresponds to a field of view of the target object, and realizes detection of the shape and position of the target object.
- the corresponding guiding structural unit such as the Fourier lens 206
- the reflected signal light with a large scattering angle passes through the Fourier lens 206, the reflected signal light of different angles is focused on the corresponding receiving unit, so as to realize the one-to-one correspondence between the reflected signal light of different angles and the receiving unit, which can improve the reflected signal light.
- the utilization rate is beneficial to reduce the total power required by the ranging chip and increase the detection distance.
- FIG. 6 is a schematic structural diagram of an array type coherent ranging chip provided by an embodiment of the present application.
- the modulated light source unit 101 in this embodiment is composed of a light source 202 , a modulator 203 and a beam splitting unit 204 .
- the modulated light source unit 101 further includes a signal generator (not shown).
- the light source 202 is a narrow linewidth laser with a center wavelength of 1550 nm, and the output light of the laser is modulated by the modulator 203, and its modulation frequency is distributed as a triangular wave with time;
- One of them is signal light, which is emitted from the on-chip emitting unit 102 (a grating in the embodiment of the present application), and illuminates the target object with a large divergence angle;
- the receiving array includes a beam splitting area 301 and a receiving module 302, wherein the beam splitting area 301 is composed of a plurality of beam splitting units, and the reference light is uniformly distributed into each receiving unit of the receiving module 302 as the intrinsic light;
- the module 302 consists of M ⁇ N receiving units 303 .
- the on-chip emission unit 102 can scan the emission direction of the signal light by adding an off-chip scanning device, such as a MEMS micromirror or a transmission/reflection optical phased array (OPA), so as to realize dynamic split field of view.
- OPA optical phased array
- the structure of the receiving unit 303 in the embodiment of the present application is as shown in FIG.
- the diffractive structure 601 receives the reflected signal light, and guides the reflected light of a specific angle to the input end of the light combining component corresponding to the specific unit in the receiving array;
- the light combining component 602 receives the reflected signal light and the input reference light, and combines the reference light and the reflected light.
- the signal light is combined into a composite signal, and the composite signal is separated into a first detection signal and a second detection signal;
- the detector 603 will receive the first detection signal and the second detection signal, and convert the first detection signal and the second detection signal is an electrical signal, and the difference value of the electrical signal is output to obtain a ranging signal.
- the detector 603 performs difference processing to obtain ranging and position signals.
- the detectors are composed of 2 ⁇ 2 balanced detectors, and the photodetection devices in the 2 ⁇ 2 balanced detection array can be based on SPAD, APD, and PIN photodetectors.
- the light combination component 602 and the detector 603 in the chip receiving array can be integrated on the same chip, or the two parts can be integrated on two chips independently, which can be connected by light or electricity.
- the function of the light combining component 602 is to combine the incident reference light E Lo and the reflected signal light
- the output forms 4 mixing signals with amplitudes of and
- the first two and the last two respectively form two sets of signals with a difference of 0 degrees and 180 degrees.
- the four signals output by the optical combination component are then received by the detector 603 in the receiving unit; the two groups of signals with a phase difference of 0° and 180° are respectively detected by the signal circuit of the detector to form a balanced detection.
- the intensity difference between the two groups of output signals of the optical combination component in It varies with time as a sawtooth or trigonometric function, so the signal intensity difference dI is a sinusoidal signal whose amplitude is proportional to the amplitude of the intrinsic light and the amplitude of the signal light.
- the signal intensity difference is also a sinusoidal signal whose amplitude is proportional to the amplitude of the intrinsic light and the amplitude of the signal light.
- the Doppler frequency shift is superimposed in the reflected signal, resulting in different frequency differences between the rising and falling edges of the frequency in the coherent superposition signal with the reference light, as shown in Figure 5.
- the incident light signal is converted into an electrical signal by the detector 603.
- the high-frequency component and the DC component are filtered out, and the output is amplified. output signal, which can filter out the effect of phase on the signal.
- the ranging signal output by the array coherent ranging chip is received through the signal processing unit, and the distance of the target object is obtained through spectrum analysis and calculation.
- FIG. 7 is a schematic structural diagram of an array type coherent ranging chip provided by an embodiment of the present application.
- the modulated light source unit 101 is composed of a light source 202 , a modulator 203 and a beam splitting unit 204 .
- the output light of the light source 202 is modulated by the modulator 203, and then the modulated light beam is divided into two paths by the beam splitting unit 204, one of which is the signal light, which is emitted from the on-chip emitting unit 102 and illuminates the target object with a large divergence angle ;
- the other way is that the reference light enters each receiving unit through the receiving array as the reference light.
- the receiving array includes a beam splitting area 301 and a receiving module 302, wherein the beam splitting area 301 is composed of a plurality of beam splitting units, and the reference light is uniformly distributed into each receiving unit of the receiving module 302 as the intrinsic light;
- the module 302 consists of M ⁇ N receiving units 303 .
- the on-chip emission unit 102 is composed of an optical phased array (OPA).
- OPA optical phased array
- the signal light separated from the beam splitting unit 204 enters the beam splitting area 704 of the phased array through the waveguide, and then evenly enters the phased array phased area 703 connected with each channel of the phased array, and passes through each channel in the phased area.
- the phase modulator 705 individually controls the phase distribution of each channel.
- the phased array output unit 702 can be deflected in one direction; in addition, the signal light can be deflected in another direction by utilizing the dispersion characteristics of the phased array output unit 702 , so that the scanning function of the coherent ranging chip in two dimensions can be realized.
- the number of channels and structural parameters of the phased array high-quality beams can be easily achieved and side lobes can be suppressed; and compared with MEMS micromirrors, the phased array can be more easily integrated on the ranging chip .
- the structure of the receiving unit 303 in the embodiment of the present application is as shown in FIG.
- the diffractive structure 601 receives the reflected signal light, and guides the reflected light of a specific angle to the input end of the light combining component corresponding to the specific unit in the receiving array; the light combining component 602 receives the reflected signal light and the input reference light, and combines the reference light and the reflected light.
- the signal light is combined into a composite signal, and the composite signal is separated into a first detection signal and a second detection signal; the detector 603 will receive the first detection signal and the second detection signal, and convert the first detection signal and the second detection signal is an electrical signal, and the difference value of the electrical signal is output to obtain a ranging signal.
- the ranging signal output by the array coherent ranging chip is received through the signal processing unit, and the distance of the target object is obtained through spectrum analysis and calculation.
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Abstract
Description
Claims (10)
- 一种阵列式相干测距芯片,其特征在于,包括:调制光源单元、片上发射单元以及接收阵列,所述调制光源单元用于产生调制光束,并将所述调制光束分为信号光和参考光输出;所述片上发射单元用于将所述信号光以预设发散角照射到目标物体上反射形成多角度信号光;所述接收阵列用于接收所述参考光和所述多角度信号光,并将所述参考光和每个角度的信号光分别进行转换探测后得到多个测距信号。
- 根据权利要求1所述的阵列式相干测距芯片,其特征在于,所述接收阵列包括:多个接收单元,每个接收单元包括衍射结构、光组合组件和探测器,所述衍射结构接收相应角度的反射光,将相应角度的反射光引导到所述光组合组件的输入端;所述光组合组件接收经过分束后的参考光和相应角度的反射光,将所述参考光和相应角度的反射光组合成复合信号,并将所述复合信号分离为第一检测信号和第二检测信号;所述探测器接收所述第一检测信号和所述第二检测信号,将所述第一检测信号和所述第二检测信号转换为电信号,并将电信号的差值输出得到所述测距信号。
- 根据权利要求2所述的阵列式相干测距芯片,其特征在于,所述衍射结构包括一维或二维衍射光学元件;所述光组合组件包括衍射光学元件,衍射光栅、超表面、Y分支、多模干涉耦合器、定向耦合器、星形耦合器或偏振分束器中的任意一种;所述探测器包括雪崩光电二极管、光电倍增管或PIN二极管中的任意一种。
- 根据权利要求1所述的阵列式相干测距芯片,其特征在于,所述调制光源单元包括:调制单元和分束单元,所述调制单元包括光源和信号发生器,所述光源的调制方式为外调制或内调制,当基于外调制原理时,所述调制单元还包括强度调制器;当基于内调制原理时,所述调制单元不包括强度调制器;所述分束单元包括Y分支、星形耦合器、多模干涉耦合器、定向耦合器、偏振分束器、部分衍射部分透射的波导光栅结构中的任意一种。
- 根据权利要求1所述的阵列式相干测距芯片,其特征在于,所述调制光源单元的 工作波长包括可见光波段和近红外波段。
- 根据权利要求1所述的阵列式相干测距芯片,其特征在于,所述片上发射单元包括:片上扩束结构和衍射结构,所述片上扩束结构将所述信号光进行整形后输出;所述衍射结构将整形后的信号光以预设发散角照射到目标物体上反射形成多角度信号光。
- 根据权利要求6所述的阵列式相干测距芯片,其特征在于,所述片上扩束结构包括绝热倒锥形波导、平板波导凹面反射镜、基于波导层厚度渐变的平板波导透镜、基于微纳结构的折射率渐变平板波导透镜、级联分束器以及星形耦合器中的任意一种;所述衍射结构包括波导衍射光栅阵列或平板波导光栅。
- 根据权利要求1-7任一项所述的阵列式相干测距芯片,其特征在于,芯片上的光学元件和电学元件集成在单个芯片上或集成在两个芯片上,当集成在两个芯片上时,两个芯片通过光信号或电信号连接。
- 根据权利要求5所述的阵列式相干测距芯片,其特征在于,还包括:矩形波导、脊形波导及狭缝波导中的任意一种,用于对芯片上的光信号进行传输;当工作波长为可见波段时,采用基于氮化硅和硅混合集成的平台对芯片进行集成,并采用氮化硅作为波导材料;当工作波长为红外波段时,基于绝缘体上的硅平台对芯片进行集成。
- 一种阵列式相干测距系统,其特征在于,包括:信号处理单元及如权利要求1-9任一项所述的阵列式相干测距芯片,所述信号处理单元接收所述阵列式相干测距芯片输出的测距信号,经过频谱分析计算得到目标物体的距离。
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