CN212515027U - Array type coherent ranging chip and system thereof - Google Patents
Array type coherent ranging chip and system thereof Download PDFInfo
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- CN212515027U CN212515027U CN202022176394.XU CN202022176394U CN212515027U CN 212515027 U CN212515027 U CN 212515027U CN 202022176394 U CN202022176394 U CN 202022176394U CN 212515027 U CN212515027 U CN 212515027U
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Abstract
The utility model discloses an array coherent ranging chip and system thereof, this chip includes: the modulation light source unit is used for generating a modulation light beam and dividing the modulation light beam into signal light and reference light to output; the on-chip emitting unit is used for irradiating the signal light onto a target object at a preset divergence angle and reflecting the signal light to form multi-angle signal light; the receiving array is used for receiving the reference light and the multi-angle signal light, and respectively carrying out conversion detection on the reference light and the signal light at each angle to obtain a plurality of ranging signals. By implementing the utility model, the laser ranging is realized by adopting a chip mode, the structure is compact, the reliability is high, and the ranging cost is reduced; meanwhile, a coherent measurement mode is carried out by adopting a reference signal and a reflected signal, and proper reference power is selected to realize signal amplitude control, thereby enlarging the range measurement range and having the function of resisting the interference of ambient light; by receiving the multi-angle reflected light at the same time, the multi-pixel data can be processed in parallel.
Description
Technical Field
The utility model relates to a laser radar technical field, concretely relates to array coherent ranging chip and system thereof.
Background
Laser detection and ranging (LiDAR) is a remote sensing technology, which has a wide and irreplaceable application in the fields of automatic driving, virtual/augmented reality, optical communication, etc., and completes the detection of the distance to a target to be detected by emitting Laser with a specific wavelength and direction to irradiate the target to be detected and measuring a return signal.
At present, the laser radar ranging principle mainly comprises two methods, the first method is a flight time method, and the distance of an object is determined by detecting the time delay of transmitted and received light pulses, but the method has the defects that the ranging distance is short, only single-point measurement can be realized, and the anti-interference capability is weak; the second is coherent detection, and according to different laser modulation methods, the more common schemes are: frequency Modulated Continuous Wave (FMCW), Chirped Amplitude Modulated (CAM), and the like. The method has the advantages of strong environmental interference resistance and low requirement on the power of the light source.
In the prior art, in order to make a laser radar system have a large field angle and a small divergence angle, the output signal light needs to be properly processed, and the processing method generally comprises the following steps: flash (Flash), MEMS micro-mirrors, and Optical Phased Array (OPA). The optical phased array and Flash scheme has the advantages of high reliability and compact structure because the optical phased array and Flash scheme does not contain a mechanical moving or rotating structure.
As a mature scheme, Flash realizes simultaneous transmission and reception of multiple angles in a field of view based on a wide-emission-angle light source and a detector array, and obtains distance information based on a Time of flight (TOF) method. However, the total emergent power of the light source is limited by the safety power of human eyes, because the light source is emergent at multiple angles, the emitting power in a unit angle is limited, the intensity of the light signal reflected by the target is in inverse square relation with the target distance, and the time-of-flight detector array can only identify the signal higher than the noise limit, so that the detection distance is limited.
On the other hand, if the ambient light includes an emission wavelength component, the detector may be saturated due to ambient interference and signal superposition, and the target signal cannot be identified, so the Flash scheme based on the time-of-flight method is susceptible to the ambient light.
SUMMERY OF THE UTILITY MODEL
In view of this, the embodiment of the present invention provides an array type coherent ranging chip and a system thereof, so as to solve the technical problems of limited ranging and poor interference resistance of the laser radar in the prior art.
The embodiment of the utility model provides a first aspect provides an array coherent ranging chip, and this chip includes: the device comprises a modulation light source unit, an on-chip emitting unit and a receiving array, wherein the modulation light source unit is used for generating a modulation light beam and dividing the modulation light beam into signal light and reference light to be output; the on-chip emitting unit is used for irradiating the signal light onto a target object at a preset divergence angle and reflecting the signal light to form multi-angle signal light; the receiving array is used for receiving the reference light and the multi-angle signal light, and converting and detecting the reference light and the signal light of each angle respectively to obtain a plurality of ranging signals.
Optionally, the receiving array comprises: a plurality of receiving units, each receiving unit comprising a diffractive structure, a light combining component and a detector, the diffractive structure receiving reflected light of a respective angle and directing the reflected light of the respective angle to an input of the light combining component; the light combination component receives the reference light and the reflected light with corresponding angles, combines the reference light and the reflected light with corresponding angles into a composite signal, and separates the composite signal into a first 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 electric signals, and outputs the difference value of the electric signals to obtain the ranging signal.
Optionally, the receiving array further comprises: and the first beam splitting area comprises a plurality of beam splitting units, receives the reference light, and transmits the reference light to the light combination assembly of each receiving unit after beam splitting.
Optionally, the operating wavelength of the modulated light source unit includes a visible light band and a near infrared band.
Optionally, the diffractive structure comprises a one-dimensional or two-dimensional diffractive optical element; the light combining component comprises any one of a diffraction optical element, a diffraction grating, a super surface, a Y branch, a multi-mode interference coupler, a directional coupler, a star coupler or a polarization beam splitter; the detector comprises any one of an avalanche photodiode, a photomultiplier tube, or a PIN diode.
Optionally, the modulated light source unit includes: the modulation unit comprises a light source and a signal generator, the modulation mode of the light source is external modulation or internal modulation, and when amplitude modulation is realized based on an external modulation principle, the modulation unit also comprises an intensity modulator; when based on the internal modulation principle, the modulation unit does not comprise an intensity modulator; the beam splitting unit comprises 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 partially transmissive waveguide grating structure.
Optionally, the on-chip transmitting unit includes: the on-chip beam expanding structure shapes the signal light and outputs the shaped signal light; the diffraction structure irradiates the shaped signal light onto a target object at a preset divergence angle and reflects the shaped signal light to form multi-angle signal light.
Optionally, the on-chip beam expanding structure includes any one of an adiabatic inverted cone waveguide, a slab waveguide concave mirror, a slab waveguide lens based on gradual change of the thickness of a waveguide layer, a slab waveguide lens based on gradual change of the refractive index of a micro-nano structure, a cascade beam splitter and a star coupler; the diffractive structure comprises an array of waveguide diffraction gratings or a slab waveguide grating.
Optionally, the on-chip emitting unit includes an optical phased array, where the optical phased array includes a second beam splitting region, a phased region, and an exit unit, and the second beam splitting region is configured to split the signal light and output the split signal light to the phased region; the phase control area is used for carrying out phase modulation on the split signal light; the emergent unit is used for outputting the signal light subjected to the phase modulation, so that the signal light with two dimensions is irradiated on a target object.
Optionally, the on-chip emitting unit realizes scanning of the signal light in different emitting directions under the control of an external scanning device.
Alternatively, the optical and electrical components on the chip are integrated on a single chip or on two chips, which when integrated are connected by optical or electrical signals.
Optionally, the array-type coherent ranging chip further includes: any one of rectangular waveguide, ridge waveguide and slit waveguide for transmitting optical signal on the chip; when the working wavelength is a visible band, a platform based on silicon nitride and silicon hybrid integration is adopted to integrate the chip, and silicon nitride is adopted as a waveguide material; when the working wavelength is an infrared band, the chip is integrated based on a silicon platform on an insulator.
The embodiment of the utility model provides an array coherent ranging system is provided in the second aspect, this system includes: the signal processing unit reaches as the embodiment of the utility model provides an in the first aspect and any item of the first aspect array coherent ranging chip, the signal processing unit receives the ranging signal of array coherent ranging chip output, the distance that obtains the target object through spectral analysis calculation.
The embodiment of the utility model provides a technical scheme has following effect:
the array type coherent ranging chip provided by the embodiment of the utility model realizes laser ranging by adopting a chip mode, has compact structure and high reliability, and reduces the ranging cost; meanwhile, a mode of carrying out coherent measurement on a reference signal and a reflected signal is adopted, the generated ranging signal is in direct proportion to the product of the amplitudes of the reference light and the signal light, signal amplitude control can be realized by selecting proper reference power, the ranging range is expanded, and components different from the wavelength of a light source cannot form stable interference signals, so that the environment light interference resistance effect is realized; in addition, multi-angle reflected light is received in a receiving array mode, multi-pixel data can be processed in parallel, and compared with a scanning type coherent radar, the number of collected points in unit time is greatly increased.
The embodiment of the utility model provides an array coherent ranging system can realize the measurement of target object distance, simple structure, and is with low costs, can realize miniaturization and chipization, and change in integratively, and in addition, ranging system adopts coherent detection mode, not only can amplify the signal, and will unable formation stable interference signal with the different composition of light source wavelength, has anti environmental disturbance's effect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a block diagram of an array type coherent ranging chip according to an embodiment of the present invention;
fig. 2 is a block diagram of an array type coherent ranging chip according to another embodiment of the present invention;
fig. 3 is a block diagram of a receiving unit of an array type coherent ranging chip according to an embodiment of the present invention;
fig. 4 is a block diagram of an array type coherent ranging system according to an embodiment of the present invention;
fig. 5 is a modulation schematic diagram of the array type coherent ranging chip in the embodiment of the present invention;
fig. 6 is a block diagram of a coherent ranging chip according to another embodiment of the present invention;
fig. 7 is a block diagram of a coherent ranging chip according to another embodiment of the present invention.
Detailed Description
The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Furthermore, the technical features mentioned in the different embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.
Example 1
The embodiment of the utility model provides an array coherent ranging chip, as shown in FIG. 1, this chip includes: a modulation light source unit 101, an on-chip transmitting unit 102 and a receiving array 103, the modulation light source unit 101 is used for generating a modulation light beam and dividing the modulation light beam into a signal light and a reference light output; the on-chip emitting unit 102 is configured to irradiate the signal light onto a target object at a preset divergence angle and reflect the signal light to form multi-angle signal light; the receiving array 103 is configured to receive the reference light and the multi-angle signal light, and convert and detect the reference light and the signal light at each angle respectively to obtain a plurality of ranging signals.
The array type coherent ranging chip provided by the embodiment of the utility model realizes laser ranging by adopting a chip mode, has compact structure and high reliability, and reduces the ranging cost; meanwhile, a mode of carrying out coherent measurement on a reference signal and a reflected signal is adopted, the generated ranging signal is in direct proportion to the product of the amplitudes of the reference light and the signal light, signal amplitude control can be realized by selecting proper reference power, the ranging range is expanded, and components different from the wavelength of a light source cannot form stable interference signals, so that the environment light interference resistance effect is realized; in addition, multi-angle reflected light is received in a receiving array mode, multi-pixel data can be processed in parallel, and compared with a scanning type coherent radar, the number of collected points in unit time is greatly increased.
In one embodiment, as shown in fig. 2 and 3, the receiving array 103 includes: a plurality of receiving units, each receiving unit comprising a diffractive structure 601, a light combining component 602 and a detector 603, the diffractive structure 601 receiving the reflected light of the respective angle, directing the reflected light of the respective angle to an input of the respective light combining component 602; the optical combining component 602 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 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 electrical signals, and outputs a difference value of the electrical signals to obtain a ranging signal.
In particular, the light combining component 602 can be used for converting incident reference light ELoAnd reflected light of corresponding angle
The output forms 4 mixing signals with amplitudes of
And
where the first two and the last two each form 2 sets of signals that differ by 0 degrees and 180 degrees. The 4 signals output by the optical combining component 602 are received by the detector in the receiving unit; wherein, the 2 groups of signals with the phase difference of 0 degree and 180 degree are respectively formed by the signal circuit of the detector 603 to be balanced and detected. Therefore, the first detection signal and the second detection signal respectively comprise two signals, and the two signals in each detection signal respectively enter the two inputs of the balanced detector. The detector can convert incident light signals into electric signals, after difference values of the two groups of signals are obtained, high-frequency components and direct-current components are filtered, amplified and output, and then output signals are obtained by summing the squared difference signals of the two groups of signals, so that the influence of phases on the signals can be filtered.
Optionally, implementations of light combining component 602 include, but are not limited to, diffractive optical elements, diffraction gratings, super-surfaces, Y-branches, multimode interference couplers, directional couplers, star couplers, and polarizing beam splitters; the diffraction structure 601 includes a one-dimensional or two-dimensional diffraction optical element such as a waveguide diffraction grating array or a slab waveguide grating; the detector 603 is composed of 4 detection arrays corresponding to 4 output signals of the optical combining component 602 one by one, wherein the detector 603 includes any one of an avalanche photodiode, a photomultiplier, and a PIN diode.
In one embodiment, the receive array further comprises: the first beam splitting area comprises a plurality of beam splitting units, receives the reference light, and transmits the reference light to the light combination assembly of each receiving unit after beam splitting. 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 as intrinsic light by beam splitting.
In one embodiment, a modulated light source unit includes: the modulation unit comprises a light source and a signal generator, the modulation mode of the light source comprises external modulation or internal modulation, and when the amplitude modulation is realized based on the external modulation principle, the modulation unit also comprises an intensity modulator; when based on the internal modulation principle, the modulation unit does not comprise an intensity modulator. The central wavelength range of the light source in the modulated light source unit 101 is 400nm-3000nm, including visible light to near-infrared band. Alternatively, when based on external modulation, as shown in fig. 2, 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.
Specifically, various types of waveguides such as a rectangular waveguide, a ridge waveguide, a slit waveguide, and the like may be provided on the chip for transmitting the light beam; when light sources of different wave bands are selected, different waveguide implementations can be selected for different wave bands, for example, Silicon On Insulator (SOI) can be selected for a near infrared wave band, Silicon nitride can be selected as a waveguide material for a visible light wave band, and a platform based On hybrid integration of Silicon nitride and Silicon is selected.
The modulation unit modulates an output light beam of the light source to generate a light beam with a wavelength or amplitude modulation Frequency changing along with time, and the modulation type of the modulation unit comprises any one of Chirp Amplitude Modulation (CAM) or Frequency Modulation Continuous Wave (FMCW). Specifically, the modulation unit includes, but is not limited to, a mach-zehnder interferometer (MZI), a Ring Resonator interferometer (Ring Resonator), a variable optical attenuator, and the like. The beam splitting unit may furthermore comprise any of a Y-branch, a star coupler, a multimode interference coupler, a directional coupler, a polarizing beam splitter, a partially diffractive partially transmissive waveguide grating structure.
In an embodiment, the on-chip transmitting unit includes: the on-chip beam expanding structure shapes and outputs the signal light; the diffraction structure irradiates the shaped signal light onto a target object at a preset divergence angle and reflects the shaped signal light to form multi-angle signal light. Specifically, the on-chip beam expanding structure comprises any one of a heat-insulating inverted cone waveguide, a slab waveguide concave reflector, a slab waveguide lens based on gradual change of the thickness of a waveguide layer, a slab waveguide lens based on gradual change of the refractive index of a micro-nano structure, a cascade beam splitter and a star coupler; the diffractive structure comprises an array of waveguide diffraction gratings or a slab waveguide grating.
Optionally, an off-chip scanning device may be further disposed outside the chip, and configured to scan the signal light output by the on-chip emitting unit, where the off-chip scanning device may be an MEMS micro-mirror or an Optical Phase Array (OPA) with a transmissive/reflective type, and the off-chip scanning device may implement scanning in a signal light emitting direction, and implement dynamic ranging with a view angle.
In addition, a corresponding guiding structure unit can be arranged to guide the multi-angle reflected light reflected by the target object to the receiving array. Specifically, as shown in fig. 2, the guiding structure may be configured as a fourier lens 206, which can focus the reflected signal lights with different angles on a plurality of corresponding receiving units, respectively, achieve one field angle of each receiving unit corresponding to the target object, and achieve detection of the shape and position of the target object.
In an embodiment, an optical phased array may be directly arranged in the on-chip emitting unit, where the optical phased array includes a second beam splitting region, a phased region, and an emitting unit, and the second beam splitting region is configured to split the signal light and output the split signal light to the phased region; the phase control area is used for carrying out phase modulation on the split signal light; the emergent unit is used for outputting the signal light subjected to the phase modulation, so that the signal light with two dimensions is irradiated on a target object.
Specifically, the signal light split from the beam splitting unit enters the second beam splitting region through the waveguide, then uniformly enters each channel of the phase control region, and then enters the phase modulator of the phase control region, and the phase distribution of each channel is individually controlled by the phase modulator of each channel in the phase control region. The deflection of the emergent unit of the optical phased array in one direction can be realized by controlling the phase distribution among all paths of the optical phased array; in addition, by using the dispersion characteristic of the phased array emission unit, the deflection in the other direction can be realized by changing the change of the output wavelength, so that the scanning function of the coherent ranging chip on two dimensions can be realized. Moreover, by controlling the number of channels and structural parameters of the optical phased array, high-quality light beams can be conveniently realized, and side lobes are suppressed; and the optical phased array can be more easily integrated on a ranging chip than a MEMS micro-mirror.
Optionally, the exit unit may be implemented by using a grating structure, and for the signal light output by the beam splitting unit, through controlling the phase modulator and modulating a duty ratio of the exit unit, the deflection of the signal light in two directions may be implemented respectively, so as to implement the scanning of the signal light in two directions.
Example 2
The embodiment of the utility model provides an array coherent ranging system, as shown in FIG. 4, this system includes: the signal processing unit 104 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.
Specifically, if the waveform of the light beam output by the modulation light source is a triangular wave, the following relationship is satisfied between the wavelength/amplitude chirp modulation parameter of the light source of the coherent ranging chip and the target distance R and the speed v:
wherein c is the vacuum light velocity, lambda0Is the vacuum center wavelength, fSigIs the signal frequency, B is the light source wavelength or amplitude chirp modulation frequency bandwidth, T0Is a modulation period;Δ f is the rising edge signal frequency fSig+And falling edge signal frequency fSig-The difference between them.
The embodiment of the utility model provides an array coherent ranging system can realize the measurement of target object distance, simple structure, and is with low costs, can realize miniaturization and chipization, and change in integratively, and in addition, ranging system adopts coherent detection mode, not only can amplify the signal, and will unable formation stable interference signal with the different composition of light source wavelength, has anti environmental disturbance's effect.
Example 3
Fig. 2 is a schematic structural diagram of an array-type coherent ranging chip according to an embodiment of the present invention, which is a modulated light source unit 101, an on-chip emitting unit 102, and a receiving array 103, where the modulated light source unit 101 includes a light source 202, a modulator 203, and a beam splitting unit 204; the receive array 103 includes N receive units.
The light beam output by the light source 202 enters the beam splitting unit 204 to be split into two parts after being modulated by the modulator 203, and one part of the light beam directly reaches each receiving unit in the receiving array and is used as reference light; the other part of the signal light is output by the on-chip emitting unit 102, and then is irradiated on the target object at a large divergence angle, and after the reflected light is processed by the corresponding guiding structure unit, the reflected signal light at different angles will be received by the N receiving units in the receiving array 103, respectively, and each receiving unit corresponds to one field angle of the target object. Then, the reference light and the reflected light signals are converted into electric signals through a light combination component and a balance detector in the on-chip receiving unit, and then the distance and position information of the object is obtained through a signal processing part. In addition, an optical component for controlling the intensity of the light beam, such as 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 target object reflection signal received by the chip, may be provided on the chip.
Specifically, the light source 202 may be a laser or an array of lasers; the central wavelength range of the light source 202 is 400nm-3000nm, including the visible to near-infrared band; the modulator 203 modulates the output light beam of the light source to generate a light beam with a time-varying wavelength or amplitude modulation Frequency, and the modulation type includes any one of Chirp Amplitude Modulation (CAM) or Frequency Modulation Continuous Wave (FMCW), as shown in fig. 5. The beam splitting unit 204 separately refers to the modulated light beam and the signal light.
Specifically, the modulator 203 includes, but is not limited to, a Mach Zehnder Interferometer (MZI), a Ring Resonator interferometer (Ring Resonator), a variable 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 polarization beam splitter, a partially diffractive partially transmissive waveguide grating structure, and the like.
The on-chip transmitting unit 102 includes: the system comprises an on-chip beam expanding structure and a diffraction structure, wherein the on-chip beam expanding structure shapes output signal light and irradiates the signal light on a target object at a large divergence angle through the diffraction structure to form reflected signal light; the on-chip beam expanding structure comprises any one of a heat-insulating inverted cone waveguide, a slab waveguide concave reflector, a slab waveguide lens based on the gradual change of the thickness of a waveguide layer, a slab waveguide lens based on the gradual change of the refractive index of a micro-nano structure, a cascade beam splitter and a star coupler; the diffractive structure comprises an array of waveguide diffraction gratings or a slab waveguide grating.
Each receiving unit in the receiving array 103 comprises a diffractive structure, a light combining element and a detector. Before entering the receiving array 103, the reflected signal light needs to be processed by a corresponding guiding structure unit, such as a fourier lens 206, which can focus the reflected signal light at different angles on the corresponding N receiving units, respectively, so as to realize a field angle of each receiving unit corresponding to the target object, and realize detection of the shape and position of the target object.
After the reflected signal light with a large scattering angle passes through the fourier lens 206, the reflected signal light with different angles is focused on the corresponding receiving units, so that the reflected signal light with different angles and the receiving units are in one-to-one correspondence, the utilization rate of the reflected signal light can be improved, the total power required by the ranging chip can be reduced, and the detection distance can be increased.
Example 4
Fig. 6 is a schematic structural diagram of an array-type coherent ranging chip according to an embodiment of the present invention, in which a modulated light source unit 101 in this embodiment is composed of a light source 202, a modulator 203, and a beam splitting unit 204. In addition, the modulated light source unit 101 further includes a signal generator (not shown).
In the embodiment of the present invention, the light source 202 is a narrow linewidth laser with a central wavelength of 1550nm, the output light of the laser is modulated by the modulator 203, and the modulation frequency is distributed in a triangular wave along with time; then, the modulated light beam is split into two paths by the beam splitting unit 204, wherein one path is signal light, which is emitted from the on-chip emitting unit 102 (in the embodiment of the present invention, a grating) and irradiates a target object with a large divergence angle; and the other path of the reference light is that the reference light respectively enters each receiving unit through the receiving array to be used as the reference light. The receiving array comprises a beam splitting region 301 and a receiving module 302, wherein the beam splitting region 301 is composed of a plurality of beam splitting units, and the reference light is sequentially and uniformly distributed to each receiving unit of the receiving module 302 to be used as intrinsic light; the receiving module 302 is composed of M × N receiving units 303.
The embodiment of the present invention provides an on-chip emitting unit 102, which can realize the scanning of the signal light emitting direction by adding an off-chip scanning device, such as a MEMS micro-mirror or a transmission/reflection type Optical Phased Array (OPA), and realize the dynamic viewing angle ranging.
The embodiment of the present invention provides a receiving unit 303 structure as shown in fig. 3, which is composed of a diffraction structure 601, a light combining component 602, and a detector 603. The diffraction structure 601 receives the reflected signal light and guides the reflected light of a specific angle to the input end of the light combination component corresponding to a specific unit in the receiving array; the optical combining component 602 receives the reflected signal light and the input reference light, combines the reference light and the reflected signal light into a composite signal, and separates the composite signal 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 electrical signals, and outputs a difference value of the electrical signals to obtain a ranging signal.
Specifically, by appropriately adjusting the parameters of the gratings in the M × N receiving units 303, the one-to-one correspondence between the reflected signal lights at different angles and the M × N receiving units 303 can be realized, so that the reflected signal lights at different angles are input into the corresponding optical combining component 602, and are mixed with the reference light; then, the distance measurement and position signals are obtained by difference processing through the detector 603. In this embodiment, the detector is composed of a 2 × 2 balanced detector, and the optical detection devices in the 2 × 2 balanced detection array may be based on SPAD, APD, PIN photodetectors.
Specifically, the light combining component 602 and the detector 603 in the chip receiving array may be integrated on the same chip, or alternatively, the two components may be integrated on two chips separately, which may be connected optically or electrically.
In particular, the light combining element 602 functions to combine the incident reference light ELoAnd reflecting the signal light
The output forms 4 mixing signals with amplitudes of
And
where the first two and the last two each form 2 sets of signals that differ by 0 degrees and 180 degrees. The 4 signals output by the optical combining component are received by a detector 603 in the receiving unit; the 2 groups of signals with the phase difference of 0 degree and 180 degree are respectively formed by the signal circuit of the detector to be balanced and detected.
Wherein, for FMCW scheme in which the wavelength of the light source varies linearly with time, the intensity difference between the 2 sets of output signals of the optical combining component
Wherein
The signal intensity difference dI is a sinusoidal signal with an amplitude proportional to the intrinsic light amplitude and the signal light amplitude, which varies as a sawtooth or trigonometric function over time. For CAM schemes in which the amplitude chirp frequency of the light source varies linearly with time, the low frequency component of the difference in the intensity of the 2 sets of output signals of the optical combining element is proportional to
The signal intensity difference is also a sinusoidal signal with an amplitude proportional to the intrinsic light amplitude and the signal light amplitude.
For the above two light source modulation modes, doppler shift is superimposed in the reflected signal due to the movement of the target object, so that different frequency differences are generated at the rising and falling edges of the frequency in the superimposed signal coherent with the reference light, as shown in fig. 5. Then, the incident light signal is converted into an electric signal through the detector 603, after the difference value of the two groups of signals is obtained, the high-frequency component and the direct-current component are filtered, amplified and output, and then the output signal is obtained by summing the squared difference value signals of the two groups of signals, so that the influence of the phase on the signals can be filtered. And finally, receiving ranging signals output by the array coherent ranging chip through a signal processing unit, and calculating the distance of the target object through spectrum analysis.
Example 5
Fig. 7 is a schematic structural diagram of an array-type coherent ranging chip according to an embodiment of the present invention, in which the modulated light source unit 101 includes a light source 202, a modulator 203, and a beam splitting unit 204.
In the embodiment of the present invention, the output light of the light source 202 is modulated by the modulator 203, and then the modulated light beam is split into two paths by the beam splitting unit 204, wherein one path is the signal light, and is emitted from the on-chip emitting unit 102 to irradiate a target object with a large divergence angle; and the other path of the reference light is that the reference light respectively enters each receiving unit through the receiving array to be used as the reference light. The receiving array comprises a beam splitting region 301 and a receiving module 302, wherein the beam splitting region 301 is composed of a plurality of beam splitting units, and the reference light is sequentially and uniformly distributed to each receiving unit of the receiving module 302 to be used as intrinsic light; the receiving module 302 is composed of M × N receiving units 303.
The embodiment of the present invention provides an on-chip emitting unit 102, which is composed of an Optical Phased Array (OPA). The signal light split from the beam splitting unit 204 enters the beam splitting area 704 of the phased array through the waveguide, and then uniformly enters the phased array area 703 connected to each channel of the phased array, and the phase distribution of each channel is individually controlled by the phase modulator 705 of each channel in the phased array area. Moreover, the deflection of the phased array emission unit 702 in one direction can be realized by controlling the phase distribution among the paths of the phased array; in addition, by using the dispersion characteristic of the phased array emission unit 702, the deflection of the signal light in the other direction can be realized, and thus the scanning function of the coherent ranging chip in two dimensions can be realized. Moreover, by controlling the number of channels and structural parameters of the phased array, high-quality light beams can be conveniently realized, and the suppression of side lobes is realized; moreover, compared with the MEMS micro-mirror, the phased array can be more easily integrated on a ranging chip.
The embodiment of the present invention provides a receiving unit 303 structure as shown in fig. 3, which is composed of a diffraction structure 601, a light combining component 602, and a detector 603. The diffraction structure 601 receives the reflected signal light and guides the reflected light of a specific angle to the input end of the light combination component corresponding to a specific unit in the receiving array; the optical combining component 602 receives the reflected signal light and the input reference light, combines the reference light and the reflected signal light into a composite signal, and separates the composite signal 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 electrical signals, and outputs a difference value of the electrical signals to obtain a ranging signal. And then, receiving ranging signals output by the array coherent ranging chip through a signal processing unit, and calculating the distance of the target object through spectrum analysis.
Although the present invention has been described in detail with respect to the exemplary embodiments and the advantages thereof, those skilled in the art will appreciate that various changes, substitutions and alterations can be made to the embodiments without departing from the spirit of the invention and the scope of the invention as defined by the appended claims. For other examples, one of ordinary skill in the art will readily appreciate that the order of the process steps may be varied while maintaining the scope of the present invention.
Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
Claims (10)
1. An array-type coherent ranging chip, comprising: a modulated light source unit, an on-chip transmitting unit, and a receiving array,
the modulation light source unit is used for generating a modulation light beam and dividing the modulation light beam into signal light and reference light for output;
the on-chip emitting unit is used for irradiating the signal light onto a target object at a preset divergence angle and reflecting the signal light to form multi-angle signal light;
the receiving array is used for receiving the reference light and the multi-angle signal light, and converting and detecting the reference light and the signal light of each angle respectively to obtain a plurality of ranging signals.
2. The array-type coherent ranging chip of claim 1, wherein the receiving array comprises: a plurality of receiving units, each receiving unit comprising a diffractive structure, a light combining element and a detector,
the diffraction structure receives the reflected light of the corresponding angle and guides the reflected light of the corresponding angle to the input end of the light combination component;
the light combination component receives the divided reference light and the reflected light with the corresponding angle, combines the reference light and the reflected light with the corresponding angle into a composite signal, and separates the composite signal into a first 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 electric signals, and outputs the difference value of the electric signals to obtain the ranging signal.
3. The array-type coherent ranging chip of claim 2,
the diffractive structure comprises a one-dimensional or two-dimensional diffractive optical element;
the light combining component comprises any one of a diffraction optical element, a diffraction grating, a super surface, a Y branch, a multi-mode interference coupler, a directional coupler, a star coupler or a polarization beam splitter;
the detector comprises any one of an avalanche photodiode, a photomultiplier tube, or a PIN diode.
4. The array-type coherent ranging chip of claim 1, wherein the modulated light source unit comprises: a modulation unit and a beam splitting unit,
the modulation unit comprises a light source and a signal generator, the modulation mode of the light source is external modulation or internal modulation, and when the modulation unit is based on the external modulation principle, the modulation unit also comprises an intensity modulator; when based on the internal modulation principle, the modulation unit does not comprise an intensity modulator;
the beam splitting unit comprises 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 partially transmissive waveguide grating structure.
5. The array-type coherent ranging chip of claim 1, wherein the operating wavelength of the modulated light source unit comprises a visible light band and a near infrared band.
6. The array-type coherent ranging chip of claim 1, wherein the on-chip transmitting unit comprises: an on-chip beam expanding structure and a diffractive structure,
the on-chip beam expanding structure shapes the signal light and outputs the shaped signal light;
the diffraction structure irradiates the shaped signal light onto a target object at a preset divergence angle and reflects the shaped signal light to form multi-angle signal light.
7. The array-type coherent ranging chip of claim 6,
the on-chip beam expanding structure comprises any one of a heat-insulating inverted cone waveguide, a slab waveguide concave reflector, a slab waveguide lens based on gradual change of the thickness of a waveguide layer, a slab waveguide lens based on gradual change of the refractive index of a micro-nano structure, a cascade beam splitter and a star coupler;
the diffractive structure comprises an array of waveguide diffraction gratings or a slab waveguide grating.
8. The array-type coherent ranging chip of claim 1, wherein the optical elements and the electrical elements on the chip are integrated on a single chip or on two chips, and when integrated on the two chips, the two chips are connected by optical signals or electrical signals.
9. The array-type coherent ranging chip of claim 5, further comprising: any one of rectangular waveguide, ridge waveguide and slit waveguide for transmitting optical signal on the chip;
when the working wavelength is a visible band, a platform based on silicon nitride and silicon hybrid integration is adopted to integrate the chip, and silicon nitride is adopted as a waveguide material;
when the working wavelength is an infrared band, the chip is integrated based on a silicon platform on an insulator.
10. An array-type coherent ranging system, comprising: a signal processing unit and the array-type coherent ranging chip of any one of claims 1 to 9,
and the signal processing unit receives the ranging signals output by the array type coherent ranging chip and obtains the distance of the target object through spectral analysis and calculation.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112051582A (en) * | 2020-09-28 | 2020-12-08 | 国科光芯(海宁)科技股份有限公司 | Array type coherent ranging chip and system thereof |
| CN113267789A (en) * | 2021-04-30 | 2021-08-17 | 西安工业大学 | Infrared full-waveband two-dimensional four-directional polarization modulation grating |
| CN113703244A (en) * | 2021-08-19 | 2021-11-26 | 扬州大学 | Large-scale integrated electro-optic micro-ring optical phased array |
| CN114646941A (en) * | 2022-05-13 | 2022-06-21 | 武汉镭晟科技有限公司 | Electrically-controlled pulse laser for coherent laser radar |
| CN114935398A (en) * | 2022-05-26 | 2022-08-23 | 安徽至博光电科技股份有限公司 | Integrated optical chip and method for large-range scanning vibration measurement |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112051582A (en) * | 2020-09-28 | 2020-12-08 | 国科光芯(海宁)科技股份有限公司 | Array type coherent ranging chip and system thereof |
| CN113267789A (en) * | 2021-04-30 | 2021-08-17 | 西安工业大学 | Infrared full-waveband two-dimensional four-directional polarization modulation grating |
| CN113703244A (en) * | 2021-08-19 | 2021-11-26 | 扬州大学 | Large-scale integrated electro-optic micro-ring optical phased array |
| CN113703244B (en) * | 2021-08-19 | 2023-12-19 | 扬州大学 | Large-scale integrated electro-optical micro-ring optical phased array |
| CN114646941A (en) * | 2022-05-13 | 2022-06-21 | 武汉镭晟科技有限公司 | Electrically-controlled pulse laser for coherent laser radar |
| CN114935398A (en) * | 2022-05-26 | 2022-08-23 | 安徽至博光电科技股份有限公司 | Integrated optical chip and method for large-range scanning vibration measurement |
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