CN116243281A

CN116243281A - Optical chip module, laser radar, movable equipment and optical power adjusting method

Info

Publication number: CN116243281A
Application number: CN202310368875.6A
Authority: CN
Inventors: 朱琳; 汪敬
Original assignee: Suteng Innovation Technology Co Ltd
Current assignee: Suteng Innovation Technology Co Ltd
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2023-06-09

Abstract

The application discloses an optical chip module, a laser radar, a movable device and an optical power adjusting method. The optical chip module comprises an optical chip and an optical modulation module, wherein the optical chip comprises a cladding, at least two receiving waveguides, at least two photoelectric detection modules and the optical modulation module. The receiving waveguides are used for receiving echo signals, and the receiving waveguides are arranged at intervals along a second preset direction. The photoelectric detection modules are in one-to-one correspondence with the receiving waveguides and are used for receiving local oscillation signals and echo signals output through the receiving waveguides and generating first beat signals, and the first beat signals comprise first signal parts and second signal parts with constant frequencies. The optical modulation module is used for receiving one of the local oscillation signals or the echo signals, and performing frequency shift and/or delay processing to reduce the maximum value of the frequency values of the first signal part and the second signal part of the first beat frequency signal generated by the photoelectric detection module, so as to improve the current situation that the ADC sampling rate adopted in the laser radar in the related art is higher.

Description

Optical chip module, laser radar, movable equipment and optical power adjusting method

Technical Field

The application relates to the technical field of laser ranging, in particular to an optical chip module, a laser radar, movable equipment and an optical power adjusting method.

Background

Currently, some frequency modulated continuous wave (Frequency Modulated Continuous Wave, FMCW) lidars in the related art include a light source module, an optical chip module, and an analog-to-digital converter (Analog to Digital Converter, ADC). The light source module is used for generating a source light signal, and the source light signal is split into a detection signal and a local oscillation signal; the detection signal is reflected by the target object to form an echo signal. The FMCW laser radar receives the local oscillation signal and the echo signal through the optical chip module to obtain beat frequency signals of the local oscillation signal and the echo signal, wherein the beat frequency signals carry difference frequency information of the local oscillation signal and the echo signal. The FMCW radar acquires the beat frequency signal through the ADC to obtain the frequency of the beat frequency signal, so that the information of the distance, the speed and the like of the target object relative to the laser radar can be obtained according to the frequency of the beat frequency signal.

Because a rotatable optical scanner device exists in the FMCW laser radar, the optical scanner device rotates by a certain angle in the process that a detection signal is emitted to a target object through the optical scanner device and reflected to the optical scanner device through the target object; therefore, the specific positions of the light spots of the echo signals falling on the optical chip are different under different detection distances. Therefore, some FMCW lidars in related art use array receiving waveguides to receive echo signals, and the receiving waveguides are arranged at intervals to expand a light receiving area for receiving the echo light; one of the receiving waveguides is used for receiving the echo signals reflected by the target object at a shorter distance, and the receiving waveguide which is farther away from the receiving waveguide is used for receiving the echo signals reflected by the target object at a longer distance.

In order to realize beat frequency of the local oscillation signal and the echo signal, the laser radar also comprises a photoelectric detection module. The photoelectric detection module can be integrated in the optical chip module; each photoelectric detection module is arranged corresponding to a receiving waveguide and is used for receiving the local oscillation signal and the echo signal output by the corresponding receiving waveguide and outputting a beat signal formed by the local oscillation signal and the echo signal. Each ADC is arranged corresponding to a photoelectric detection module and is used for collecting beat frequency signals so as to obtain the frequency of the beat frequency signals. The ADC in the related art needs to have a higher sampling rate, which increases the hardware cost of the lidar.

Disclosure of Invention

The application provides an optical chip module, a laser radar, a movable device and an optical power adjusting method, so as to improve the current situation that the ADC sampling rate adopted in the laser radar in the related art is higher.

In a first aspect, the present application provides an optical chip module, including optical chip and optical modulation module, the optical chip includes: a cladding layer; the receiving waveguides are embedded in the cladding, extend along a first preset direction and are provided with a first end and a second end which are opposite to each other, the first end is used for receiving echo signals, the receiving waveguides are arranged at intervals along a second preset direction, and the second preset direction is intersected with the first preset direction; the photoelectric detection modules are arranged in one-to-one correspondence with the receiving waveguides, and are used for receiving local oscillation signals and echo signals output through the receiving waveguides and generating first beat signals, wherein the first beat signals comprise first signal parts with constant frequency and second signal parts with constant frequency; the optical path upstream of at least one photoelectric detection module is provided with an optical modulation module, and the optical modulation module is used for receiving one of the local oscillation signals or the echo signals and performing frequency shift and/or delay processing so as to reduce the maximum value of the frequency values of the first signal part and the second signal part of the first beat frequency signals generated by the photoelectric detection module.

In a second aspect, the present application also provides a frequency modulated continuous wave lidar, the frequency modulated continuous wave lidar comprising: the light source module is used for generating a source light signal; and the optical chip module.

In a third aspect, the present application also provides a mobile device, including the lidar.

In a fourth aspect, the present application further provides an optical power adjustment method, which is applied to, for example, the laser radar, where the light source module includes a light source component and a power adjustment component, the light source component is configured to generate an initial laser signal, the power adjustment component includes a power adjustment unit and a power adjustment circuit, the power adjustment unit is configured to receive the initial laser signal, and the power adjustment circuit is configured to provide an injection current or an injection voltage to the power adjustment unit, so that the power adjustment unit performs power adjustment on the initial laser signal to output a source optical signal with a constant target output power; the optical power adjusting method comprises the following steps: determining the association relation between the power attenuation coefficient of the power regulating unit and the injection current; determining a target injection current of the power regulating unit according to the input power, the target output power and the association relation of the power regulating unit; and injecting the target injection current into the power conditioning unit; alternatively, the optical power adjustment method includes: determining the association relation between the power attenuation coefficient of the power regulating unit and the injection voltage; determining a target injection voltage of the power regulating unit according to the input power, the target output power and the association relation of the power regulating unit; and injecting the target injection voltage into the power conditioning unit.

The beneficial effects of this application are: after the local oscillation signal or the echo signal can be processed through the optical modulation module, the frequency value of the first signal part and the frequency value of the second signal part of the first beat frequency signal generated by the photoelectric detection module are reduced, the sampling rate of the ADC can be reduced, the sampling requirement can be met without using a high-speed ADC, and therefore the hardware cost of the laser radar can be reduced.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related art, the drawings that are required to be used in the embodiments or the related technical descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.

FIG. 1 is a schematic view of a portion of a laser radar according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a first beat signal generated by a triangular wave according to an embodiment of the present application;

fig. 3 is a schematic composite spectrum diagram of beat frequencies of first beat signals corresponding to maximum detection distances of different receiving waveguides before local oscillation signals are adjusted in an embodiment of the present application;

Fig. 4 is a schematic composite spectrum diagram of beat frequencies of first beat signals corresponding to maximum detection distances of different receiving waveguides after local oscillation signals are adjusted in an embodiment of the present application;

fig. 5 is a time-frequency diagram of a first beat signal before and after a frequency shift process of a local oscillation signal according to an embodiment of the present application;

FIG. 6 is a schematic view of a portion of a laser radar according to another embodiment of the present disclosure;

fig. 7 is a schematic time-frequency diagram of a first beat signal before and after delay processing of a local oscillation signal according to an embodiment of the present application;

FIG. 8 is a schematic diagram of a laser radar according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of a light source module according to an embodiment of the disclosure;

FIG. 10 is a time domain waveform diagram of a first beat signal before power adjustment according to an embodiment of the present application;

FIG. 11 is a time domain waveform diagram of a first beat signal after power adjustment according to an embodiment of the present application;

FIG. 12 is a flow chart of the optical power adjustment according to an embodiment of the present application;

fig. 13 is a schematic flow chart of optical power adjustment in another embodiment of the present application.

Reference numerals:

10. an optical chip module; 11. an optical chip; 111. a cladding layer; 112. a receiving waveguide; 113. a first receiving waveguide; 114. a second receiving waveguide; 115. a photoelectric detection module; 115a, a mixer; 115b, balanced photodetectors; 116. a first photoelectric detection module; 117. a second photoelectric detection module; 118. a launch waveguide; 119. a nonlinear calibration module; 119a, a first beam splitter; 119b, a first delay line; 119c, a photodetection assembly; 12. a light modulation module; 121. a frequency shifter; 122. a power regulator; 123. a delay unit; 13. a light splitting module; 20. a light source module; 21. a light source assembly; 22. a power adjustment assembly; 221. a power adjustment unit; 221a, a second power regulator; 221b, a second beam splitter; 222. a power adjustment circuit; 30. a first analog-to-digital conversion module; 40. and a second analog-to-digital conversion module.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

The application provides an optical chip module, a laser radar, a mobile device and an optical power adjusting method, so as to solve the problem that an analog-to-digital converter (Analog to Digital Converter, ADC) is required to have a higher sampling rate in the prior art, which increases the hardware cost of the laser radar.

In a first aspect, the present application provides an optical chip module 10, where the optical chip module 10 may be applied to a laser radar, and the laser radar may measure information such as a distance, a speed, etc. of a target object relative to the laser radar by using a radio signal. Taking a laser radar as a frequency modulation continuous wave (Frequency Modulated Continuous Wave, FMCW) laser radar as an example, the FMCW laser radar generates a source optical signal, wherein the source optical signal refers to a laser signal with modulated frequency, the source optical signal can be a frequency modulation continuous wave signal, and a modulation waveform of the source optical signal can be a triangular wave, a sawtooth wave or other waveforms. The FMCW laser radar mainly comprises the steps of transmitting a continuous detection signal to a target object, receiving a signal (echo signal) reflected from the target object, generating coherence between the echo signal and a local oscillation signal, obtaining a beat signal with the frequency being the difference between the instantaneous frequencies of the echo signal and the local oscillation signal, obtaining the frequency of the beat signal through an analog-to-digital converter (Analog to Digital Converter, ADC), and obtaining the information of the distance, the speed and the like of the target object relative to the laser radar through processing and analyzing the frequency of the beat signal. The optical chip module 10 is configured to receive the local oscillation signal and the echo signal, and generate a beat signal with a frequency equal to a difference between instantaneous frequencies of the echo signal and the local oscillation signal by generating coherence between the echo signal and the local oscillation signal. In the embodiment of the application, the target object is also called a reflector, and the target object may be a person, a mountain, a vehicle, a tree, a bridge, or the like. The laser radar can be applied to various fields such as intelligent transportation, automatic driving, atmospheric environment monitoring, geographical mapping, unmanned aerial vehicle and the like, and can be used for completing the fields such as distance measurement, speed measurement, target tracking, imaging identification and the like.

Specifically, as shown in fig. 1, the optical chip module 10 is a module for receiving a local oscillation signal and an echo signal in a laser radar, and includes an optical chip 11 and an optical modulation module 12. The optical chip 11 includes a substrate, a cladding 111, at least two receiving waveguides 112, and at least two photoelectric detection modules 115, which are not shown, and a specific structure of the optical chip 11 will be described below.

For the foregoing substrate, referring to fig. 1, the substrate is a base material for laying the cladding 111; in this embodiment, the substrate is made of silicon, and it is understood that in other embodiments of the present application, the substrate may be made of other suitable materials, such as silicon nitride, and the like. It should be noted that the substrate is intended to perform a bearing support function on the cladding 111 during the fabrication of the optical chip 11; in some cases, the substrate may actually be omitted.

For the aforementioned cladding layer 111, please continue with reference to fig. 1, the cladding layer 111 is deposited or grown on a substrate, which is one of the main structures constituting the optical chip 11, and is the structure to which the receiving waveguide 112 and the photodetection module 115 are attached. The material of the cladding 111 is generally different from the substrate, and may be made of silicon oxide or silicon oxynitride.

For the aforementioned receiving waveguide 112, please continue to refer to fig. 1, the receiving waveguide 112 is embedded in the cladding 111, and the receiving waveguide 112 extends along the first predetermined direction XX (i.e. the extending direction of the receiving waveguide 112 is the first predetermined direction XX) when viewed along the thickness direction (i.e. the direction perpendicular to the drawing sheet) of the optical chip 11. The receiving waveguide 112 has a first end and a second end opposite to each other, the first end being configured to receive the echo signal, and the second end being configured to output the echo signal so that the echo signal propagates downstream. The refractive index of the receiving waveguide 112 is greater than that of the cladding 111, so that the receiving waveguide 112 and the cladding 111 together form a structure along which echo signals can be stably transmitted, and the echo signals are unlikely to overflow out of the optical chip 11 via the cladding 111. The receiving waveguide 112 may be made of silicon having a refractive index greater than that of the cladding 111, but may be made of other materials having a refractive index greater than that of the cladding 111, such as silicon nitride. The receiving waveguides 112 are arranged at intervals along a second preset direction YY, and the second preset direction YY intersects with the first preset direction XX. In this embodiment, the first preset direction XX is perpendicular to the thickness direction of the optical chip 11; the second preset direction YY is perpendicular to the thickness direction and the first preset direction XX, respectively, and it can be understood that in other embodiments of the present application, other included angles, such as 85 degrees, 95 degrees, etc., may be formed between the second preset direction YY and the first preset direction XX.

Because a rotatable optical scanner device exists in the laser radar, the optical scanner device rotates by a certain angle in the process that a detection signal is emitted to a target object through the optical scanner device and reflected to the optical scanner device through the target object; the angle of the relative rotation is generally a two-dimensional rotation angle formed by a fast axis and a slow axis. For example, when the optical scanning device includes a turning mirror that performs horizontal scanning and a galvanometer that performs vertical scanning, the field of view of the horizontal scanning is larger, the turning mirror rotates faster, the field of view of the vertical scanning is smaller, and the galvanometer rotates slower; at this time, the fast axis corresponds to the turning mirror, and the slow axis corresponds to the oscillating mirror. As can be seen from the above description, the positions of the echo signals with different flight distances on the optical chip 11 are also different, for example, the echo signals corresponding to different detection distances may have relative offsets in two directions; for convenience of description, the effect of the difference in the spot offset of the echo signal on the optical chip 11 caused by the different detection distances is referred to as walk-off effect (walk-off effect) in this application. Generally, the positional offset caused by the slow axis angular deflection is small; accordingly, the inventors of the present application have made improvements in the positional shift caused by the fast axis angular deflection. In this embodiment, the direction in which the receiving waveguides 112 are arranged is configured to coincide with the direction of positional deviation caused by the fast axis angular deflection of the optical scanning module; as such, each receiving waveguide 112 may then be used to receive echo signals reflected by target objects at different distances. The number of receiving waveguides 112 may be 2, 3, 4 or more, wherein one receiving waveguide 112 is used to receive echo signals reflected by a target object at a shorter distance, and the receiving waveguide 112 further from the receiving waveguide 112 is used to receive echo signals reflected by a target object at a longer distance.

In this embodiment, each receiving waveguide 112 is divided into a first receiving waveguide 113 and a second receiving waveguide 114, and along the second preset direction YY, the first receiving waveguide 113 is one receiving waveguide 112 located at the outermost side of each receiving waveguide 112, and all the second receiving waveguides 114 are located at the same side of the first receiving waveguide 113. In use, the first receiving waveguide 113 may be configured to receive echo signals reflected by a relatively close range target object and the second receiving waveguide 114 may be configured to receive echo signals reflected by a relatively far range target object. For example, referring to fig. 1, in the present embodiment, the optical chip 11 includes more than two second receiving waveguides 114; the first receiving waveguide 113 is configured to receive an echo signal reflected by a target object within a range from 0 to a first distance R1 from the laser radar; along the direction that the first receiving waveguide 113 points to the second receiving waveguide 114, the 1 st second receiving waveguide 114 is configured to receive echo signals reflected by a target object within a range from a first distance R1 to a second distance R2; the 2 nd second receiving waveguide 114 is configured to receive echo signals reflected by the target object in the interval from the second distance R2 to the third distance R3; the first pitch, the second pitch, and the third pitch are sequentially increased. In some embodiments, rn=n×r1, N is an integer greater than or equal to 1; this ensures that the detection distance of each receiving waveguide 112 can form a continuous distance range and that the detection ranges of each receiving waveguide 112 are approximately the same. It is understood that in other embodiments of the present application, the optical chip 11 may also include only one second receiving waveguide 114.

For the photodetection module 115, still referring to fig. 1, the photodetection module 115 is disposed in one-to-one correspondence with the receiving waveguide 112, and the photodetection module 115 is configured to receive the local oscillation signal and the echo signal output via the receiving waveguide 112, and generate a first beat signal. The first beat signal is a signal with a frequency being the difference between the instantaneous frequencies of the local oscillation signal and the echo signal, and the beat signal can also be called a beat signal, a difference signal and the like. The first beat signal flows to a downstream analog-to-digital conversion module, so that the frequency of the first beat signal is obtained, and the signal processing module of the laser radar can calculate the distance and the speed of the target object relative to the laser radar according to the frequency. In this embodiment, the local oscillation signal is a triangular wave signal; correspondingly, the first beat signal comprises a first signal part with constant frequency, a second signal part with constant frequency and a third signal part with frequency decreasing first and then rising second; the first signal part is a signal part formed by the beat frequency of the upper sweep part of the local oscillation signal and the upper sweep part of the echo signal, the second signal part is a signal part formed by the beat frequency of the lower sweep part of the local oscillation signal and the lower sweep part of the echo signal, and the third signal part is a signal part positioned between the first signal part and the second signal part in the time domain.

In this embodiment, the photo-detection module 115 includes a mixer 115a and a balanced photo-detector 115b. The mixer 115a has two input ports, one of which is used for receiving the local oscillation signal and the other of which is used for receiving the echo signal output by the receiving waveguide 112; thus, the local oscillation signal and the echo signal can generate beat frequency in the local oscillation signal and the echo signal to obtain two beat frequency optical signals, namely a first beat frequency optical signal and a second beat frequency optical signal. Alternatively, the mixer 115a is a 180 degree mixer, whose output two optical signals are 180 degrees out of phase. The balanced photodetector 115b is connected to two output terminals of the mixer 115a, and is configured to perform balanced detection on the first beat optical signal and the second beat optical signal, and output a signal corresponding to the first beat optical signal, where the frequency of the first beat signal is identical to the frequency of the first/second beat optical signal. It should be understood that, even though the photo-detection module 115 includes the mixer 115a and the balance photo-detector 115b as an example in the present embodiment, the application is not limited thereto, as long as the photo-detection module 115 is guaranteed to receive the local oscillation signal and the detection optical signal and convert the beat frequency signals of the two signals into electrical signals. For example, in other embodiments of the present application, the photodetection module 115 comprises a photodetector; the photoelectric detector is used for receiving the local oscillation signal and the echo signal so as to enable the local oscillation signal and the echo signal to beat frequency, and is also used for converting the obtained beat frequency signal into an electric signal, namely a first beat frequency signal.

In this embodiment, each of the above-mentioned photo-detection modules 115 is divided into a first photo-detection module 116 and a second photo-detection module 117. The first photoelectric detection module 116 is disposed corresponding to the first receiving waveguide 113, and is configured to receive the local oscillation signal and the echo signal output by the first receiving waveguide 113. The second photoelectric detection module 117 is disposed corresponding to the second receiving waveguide 114, and is configured to receive the local oscillation signal and the echo signal output by the second receiving waveguide 114.

The above is a description of the optical chip 11, and the description of the optical modulation module 12 will be started below.

Of course, before describing the light modulation module 12, the beat frequency of the different photodetection modules 115 of the above-mentioned optical chip 11 when the light modulation module 12 is not adopted will be described below.

As shown in fig. 2, taking the modulation waveform of the source optical signal as a triangular wave linear frequency modulation as an example, the echo signal arrives at the photoelectric detection module 115 after a period of flight time and is mixed with the local oscillation signal, the first beat signal generated by the echo signal and the local oscillation signal is constant in a certain time after the flight time, and in one modulation period, the frequency of the first beat signal fluctuates up and down. Specifically, the frequency of the first beat signal is maintained at a constant first beat frequency value for a period of time, which is the first signal portion; then, the frequency of the first beat frequency signal is firstly linearly reduced to 0, and then is linearly increased to a second beat frequency value, wherein the part is a third signal part; then, the frequency of the first beat frequency signal is maintained to be a constant second beat frequency value for a period of time, and the second beat frequency value is a second signal part; next, the frequency of the first beat signal is linearly decreased to 0 and then linearly increased to the above-mentioned first beat frequency value, which is a fourth signal portion (not shown in the figure). The first beat frequency value and the second beat frequency value are useful information to be extracted. The first beat frequency value may be greater, less or equal relative to the second beat frequency value, depending on the actual scene; for example, when the target object is stationary relative to the lidar, the first beat frequency value is equal to the second beat frequency value. It should be noted that, in one first beat signal, the frequency values of the first signal portion and the second signal portion are constant values, but the frequency values of the first signal portions of the first beat signal corresponding to different detection distances are different; the frequency values of the first signal portions (or the second signal portions) of the first beat frequency signals generated by the echo signals received by the same receiving waveguide at different detection distances are different, and when the echo signals received by the receiving waveguide are the limit value (such as the maximum detection distance) of the detection interval of the receiving waveguide, the first beat frequency value (or the second beat frequency value) of the first beat frequency signals generated by the corresponding photoelectric detection module is the maximum value.

When the distance between the target object and the laser radar is larger, the flight time of the echo signal reflected by the target object is longer, which results in a larger difference between the instantaneous frequencies of the corresponding echo signal and the local oscillation signal, that is, the first beat frequency value and the second beat frequency value are larger, so that the sampling rate of the ADC is larger. As can be seen from the above configuration of each receiving waveguide 112, the first beat frequency value and the second beat frequency value corresponding to the first photo detection module 116 are smaller, and the second photo detection module 117 is larger; the first beat frequency value and the second beat frequency value corresponding to the second photodetection module 117 corresponding to the second reception waveguide 114 which is farther from the first reception waveguide 113 are larger. Please refer to fig. 3, which illustrates a composite spectrum diagram of beat frequencies corresponding to the maximum detection distances of the different receiving waveguides 112, wherein a first beat frequency value corresponding to a first photo-detection mode corresponding to the first receiving waveguide 113 is F, a first beat frequency value corresponding to the second photo-detection module 117 corresponding to the 1 st second receiving waveguide 114 is 2F, and a first beat frequency value corresponding to the second photo-detection module 117 corresponding to the 2 nd second receiving waveguide 114 is 3F along the direction in which the first receiving waveguide 113 points to the second receiving waveguide 114. According to the nyquist sampling theorem, the ADC sampling frequency required by the first photo-detecting module 116 is not lower than 2F, the ADC sampling frequency required by the 1 st second photo-detecting module 117 is not lower than 4F, and the ADC sampling frequency required by the 2 nd second photo-detecting module 117 is not lower than 6F. As can be seen from this, as the detection distance increases, the ADC sampling frequency required by the second photo-detection module 117 increases, and the corresponding ADC cost is correspondingly higher; the cost of the entire optical chip 11 is high.

Next, the beat frequency of the different photodetection modules 115 of the optical chip 11 will be described again when the light modulation module 12 is used.

An optical tuning module 12 is disposed upstream of at least one photo-detection module 115, and the optical tuning module 12 is disposed upstream of an optical path of the photo-detection module 115, and is configured to receive one of a local oscillation signal and an echo signal, and perform frequency shift processing to reduce a maximum value of frequency values of a first signal portion and the second signal portion of the first beat frequency signal generated by the photo-detection module 115. As described above, in a single first beat signal, the frequency values of the first signal portion and the second signal portion are constant, but the frequency values of the first signal portion of the first beat signal corresponding to different detection distances are different; the maximum value described above often corresponds to the limit detection distance of the receiving waveguide.

In this embodiment, the light modulation module 12 includes a frequency shifter 121. Referring to fig. 1, the frequency shifter 121 is disposed upstream of the corresponding photo-detection module 115 and is configured to receive a local oscillation signal; the frequency shifter 121 is configured to perform frequency shifting on the local oscillation signal to reduce a maximum value of frequency values of the first signal portion and the second signal portion of the first beat signal generated by the photo-detection module 115. Specifically, referring to fig. 5, the frequency shifter 121 is configured to shift the frequency of the local oscillation signal so as to decrease the frequency of the upper sweep signal of the local oscillation signal by a preset frequency f2 and increase the frequency of the lower sweep signal of the local oscillation signal by the preset frequency f2. Then, the first beat frequency value and the second beat frequency value are respectively reduced, that is, the frequency values of the first signal portion and the second signal portion can be reduced.

When the movement of the target object relative to the lidar is ignored, the maximum value f of the frequency of the first beat signal generated by the first photoelectric detection module 116 can be known according to the corresponding relation between the detection distance and the distance beat frequency ₁ The method meets the following conditions:

where R1 is the maximum detection distance corresponding to the first receiving waveguide 113, c is the flight speed of light in air, and K is the frequency modulation slope of the triangular wave signal. Due to the f ₁ Is lower, so that the frequency shifter 121 may be disposed upstream of each of the second photo-detection modules 117 instead of disposing the frequency shifter 121 upstream of the first photo-detection module 116 for processing; for example, the light modulation modules 12 are in one-to-one correspondence with the second photo detection modules 117, and are disposed upstream of the second photo detection modules 117.

The optical tuning module 12 may be configured to perform frequency shift processing on the local oscillation signal to reduce the frequency values of the first signal portion and the second signal portion of the first beat signal generated by the photo-detection module 115; that is, the frequency shift of the optical modulation module 12 may be less than or equal to the beat frequency value of the distance corresponding to the minimum detection distance of the second receiving waveguide 114. In other embodiments of the present application, the shift amount may be configured as a median value of the detection distance of the second receiving waveguide 114; compared with the frequency shifter, the frequency shifter can reduce the frequency shift amount to a certain extent, and reduce the workload of the frequency shifter; in addition, although the frequency shift amount is smaller, the frequency maximum of the first signal portion is still higher, but since the plurality of receiving waveguides 112 are configured in the present embodiment, the detection distance interval of each receiving waveguide is relatively smaller, and therefore the frequency maximum of the first signal portion corresponding to each receiving waveguide is not too high, so the requirement of the present application can be satisfied.

Further, when the optical chip 11 includes two or more second receiving waveguides 114, the first waveguide may be followed byThe receiving waveguides 113 point to the directions of the second receiving waveguides 114, and the frequency shift amounts of the frequency shifters 121 corresponding to the second receiving waveguides 114 become larger gradually, so that the frequencies of the first beat signals output by the second photoelectric detection modules 117 are lower, and the requirement on the analog-to-digital conversion modules is reduced. For example, in some embodiments, the receiving waveguides 112 are spaced evenly apart; wherein, the detection distance corresponding to the first receiving waveguide 113 is 0-R1, and the corresponding distance beat frequency is 0-f 1; along the direction in which the first receiving waveguide 113 points to the second receiving waveguide 114, the maximum detection distance of the nth receiving waveguide 112 is (n+1) times the maximum detection distance of the first receiving waveguide 113, that is, the detection distances are RN (rn+r1); wherein rn=n×r1, N is an integer greater than or equal to 1. The frequency shifter 121 corresponding to the nth receiving waveguide 112 may be configured to perform frequency shifting processing on the local oscillation signal, so that the upper sweep signal of the local oscillation signal decreases by a first frequency n×f2, and the lower sweep signal of the local oscillation signal increases by the first frequency n×f2, where N is an integer greater than or equal to 1; wherein f2=f1. In this way, the beat frequency extremum of the first beat signal generated by the first photo-detection module 116 and the second photo-detection module 117 is substantially identical; therefore, the first beat frequency value and the second beat frequency value of the first beat frequency signals output by the second photoelectric detectors can be reduced, the optical chip 11 can receive and detect by adopting the same photoelectric detection device, and the type selection and replacement of the photoelectric device are facilitated. It will be appreciated that in other embodiments of the present application, there may be a slight gap between f2 and f1, such as f2 and f1 satisfying:

This arrangement can also achieve substantially the above-described effects. In addition, the optical chip 11 may include only one second receiving waveguide 114; at this time, the frequency shifter 121 corresponding to the second receiving waveguide 114 may be configured to perform frequency shifting processing on the local oscillation signal, so that the upper sweep signal of the local oscillation signal is reduced by the first frequency f2, and the lower sweep signal of the local oscillation signal is increased by the first frequency f2. That is, when the number of the second receiving waveguides 114 is more than one, the frequency shifter 121 can be moved in the above-described mannerThe rows are arranged.

In this way, when the movement of the target object relative to the lidar is ignored, the maximum value of the frequency of the first beat signal generated by each photodetection module 115 of the optical chip 11 provided in the embodiment of the present application is approximately F, as shown in fig. 4 specifically; according to the nyquist sampling theorem, the ADC sampling frequency required by the first photo-detecting module 116 is not less than 2F. Therefore, the optical chip 11 provided by the application can improve the current situation that the sampling rate of the ADC adopted in the laser radar in the related art is higher, and can reduce the hardware cost of a certain laser radar. Of course, it should be noted that, when the target object moves relative to the lidar, the first beat frequency value and the second beat frequency value are different in magnitude; however, the above-mentioned setting of the light modulation module 12 can still reduce the first beat frequency value and the second beat frequency value, so as to achieve the technical effect of improving the current situation that the ADC sampling rate adopted in the laser radar in the related art is higher.

In addition, in the embodiment of the present application, the second photo-detection module 117 is provided with the light modulation module 12, and the first photo-detection module 116 is not provided with the light modulation module 12, so that the number of light modulation modules 12 required can be reduced on the basis of reducing the maximum value of the frequency of the first beat signal generated by the second photo-detection module 117 to reduce the sampling rate of the ADC, thereby reducing the cost of the laser radar.

As for the setting position of the frequency shifter 121, the frequency shifter 121 may be disposed on the cladding 111 as shown in fig. 1, so that the aggregation degree of the optical chip module 10 is higher. Of course, the frequency shifter 121 may also be disposed off-chip, so as to facilitate the arrangement of the frequency shifter 121.

In addition, according to practical requirements, a power regulator 122 connected in series with the frequency shifter 121 may be disposed upstream of the second photoelectric detection module 117, where the power regulator 122 is configured to regulate the power of the local oscillator signal, so as to reduce the influence of devices such as the frequency shifter 121 on the power variation of the local oscillator signal.

It should be understood that, although the present embodiment is described by taking the example that the light modulation modules 12 are correspondingly disposed upstream of each of the second photo detection modules 117, the present application is not limited thereto; in other embodiments of the present application, the optical adjustment module 12 may be correspondingly disposed at any one or more upstream sides of the above-mentioned photoelectric detection modules 115, so long as it is ensured that the optical adjustment module 12 is disposed at the upstream side of at least one photoelectric detection module 115, so as to perform frequency shift processing on the local oscillation signal, thereby achieving the above-mentioned effects.

It should also be understood that, although the present embodiment is described by taking the optical modulation module 12 for receiving and processing local oscillation signals as an example, the present application is not limited thereto; because the frequency shifting of the local oscillation signal and the echo signal is actually symmetrical, the optical modulation module 12 may also be used to receive the echo signal and perform the frequency shifting process on the echo signal, so long as the maximum value of the frequency of the first beat signal generated by the photoelectric detection module 115 can be reduced, which is not described herein.

For the above-mentioned optical modulation module 12, it should be further mentioned that, the optical modulation module 12 performs frequency shift processing on the local oscillation signal or the echo signal to achieve the effect of reducing the frequency values of the first signal portion and the second signal portion of the frequency of the first beat signal; the optical modulation module 12 may also delay the local oscillation signal, thereby achieving the above effect.

For example, referring to fig. 6, a schematic diagram of a partial module of a lidar according to other embodiments of the present application is shown, where the main difference between the embodiment shown in fig. 1 is: in this embodiment, the light modulation module 12 includes a delay unit 123; the delay unit 123 is configured to receive the local oscillation signal and delay the local oscillation signal to reduce frequency values of the first signal portion and the second signal portion of the first beat frequency signal generated by the photo-detection module 115. It should be noted that, the delay unit 123 may delay the local oscillation signal to change the optical path of the local oscillation signal, thereby changing the difference between the instantaneous frequencies of the echo signal and the local oscillation signal, so as to reduce the frequency values of the first signal portion and the second signal portion of the first beat signal generated by the second photo-detection module 117. Referring to fig. 7, after the local oscillation signal is delayed by the delay unit 123, the difference between the instantaneous frequencies of the echo signal and the local oscillation signal is reduced, so that the frequency values of the first signal portion and the second signal portion are reduced, and thus the sampling rate of the ADC can be reduced. Wherein the delay unit 123 may include a delay line; the delay unit 123 may be located outside the optical chip 11, so as to facilitate arrangement of the delay unit 123; of course, in other embodiments, the delay unit 123 may be disposed on the cladding 111.

where R1 is the maximum detection distance corresponding to the first receiving waveguide 113, c is the flight speed of light in air, and K is the frequency modulation slope of the triangular wave signal. Due to the f ₁ Is lower, so that the delay unit 123 may be disposed upstream of each of the second photo-detection modules 117 instead of being disposed upstream of the first photo-detection module 116 for processing; for example, the light modulation modules 12 are in one-to-one correspondence with the second photo detection modules 117, and are disposed upstream of the second photo detection modules 117.

The optical tuning module 12 may be configured to delay the local oscillation signal to reduce the frequency values of the first signal portion and the second signal portion of the first beat signal generated by the photo-detection module 115; that is, the delay amount of the optical modulation module 12 may be less than or equal to the optical flight time corresponding to the minimum detection distance of the second receiving waveguide 114. In other embodiments of the present application, the delay amount may be configured as an optical flight time corresponding to a median value of the detection distance of the second receiving waveguide 114; compared with the method, the method can reduce the delay amount to a certain extent and reduce the length of the delay line; in addition, although the frequency maximum of the first signal portion is still higher due to the smaller delay amount, the present embodiment is configured with a plurality of receiving waveguides 112, and the detection distance interval of each receiving waveguide is relatively smaller, so that the frequency maximum of the first signal portion corresponding to each receiving waveguide is not too high, and thus the requirement of the present application can be satisfied.

Further, when the optical chip 11 includes more than two second receiving waveguides 114, the delay amount of the delay unit 123 corresponding to each second receiving waveguide 114 may be gradually increased along the direction of the first receiving waveguide 113 to the second receiving waveguide 114, so that the frequency of the first beat signal output by each second photoelectric detection module 117 is lower, thereby reducing the requirement for the analog-to-digital conversion module. For example, in some embodiments, the receiving waveguides 112 are spaced evenly apart; wherein the first receiving waveguide 113 corresponds to a detection distance of 0 to R1, and the maximum value of the light flight time is 0 to t1, wherein,

along the direction in which the first receiving waveguide 113 points to the second receiving waveguide 114, the detection distance of the nth receiving waveguide 112 is RN to rn+1, where rn=n×r1, that is, the maximum detection distance is (n+1) times the maximum detection distance of the first receiving waveguide 113. The delay unit 123 corresponding to the nth receiving waveguide 112 may be configured to delay the local oscillation signal by n×t2; wherein t2=t1. In this way, the beat frequency values of the first beat signals generated by the first photoelectric detection modules 116 and the second photoelectric detection modules 117 are substantially identical; in this way, the frequency values of the first signal part and the second signal part of the first beat frequency signal output by each second photoelectric detection module can be reduced, and the optical chip 11 can receive and detect by adopting the same photoelectric detection device, so that the type selection and replacement of the photoelectric device are facilitated. It will be appreciated that in other embodiments of the present application, there may be a slight gap between t2 and t1, such as t2 and t1 satisfying: / >

This arrangement can also achieve substantially the above-described effects. In addition, the optical chip 11 may include only one second receiving waveguide 114; at this time, the delay unit 123 corresponding to the second receiving waveguide 114 may be configured to delay the local oscillation signal by t 2. I.e. when the second receiving waveguideWhen the number of 114 is more than one, the delay units 123 may be set in the above manner.

In this way, the maximum first beat frequency values of the first beat frequency signals generated by the photo-detection modules 115 of the optical chip 11 provided in the embodiment of the present application are all approximately F; according to the nyquist sampling theorem, the ADC sampling frequency required by the first photo-detecting module 116 is not less than 2F. Therefore, the optical chip 11 provided by the application can improve the current situation that the sampling rate of the ADC adopted in the laser radar in the related art is higher, and can reduce the hardware cost of a certain laser radar. In addition, in the embodiment of the present application, the second photo-detection module 117 is provided with the light modulation module 12, and the first photo-detection module 116 is not provided with the light modulation module 12, so that the number of light modulation modules 12 required can be reduced on the basis of reducing the maximum value of the frequency of the first beat signal generated by the second photo-detection module 117 to reduce the sampling rate of the ADC, thereby reducing the cost of the laser radar.

In addition, in other embodiments of the present application, the optical tuning module 12 may further include a frequency shifter 121 and a delay unit 123 according to actual needs, so as to shift and delay the local oscillation signal; or delay the local oscillation signal and shift the frequency of the echo signal; so long as it is ensured that the light modulation module 12 can reduce the frequency values of the first signal portion and the second signal portion.

Furthermore, in an embodiment of the present application, the optical chip 11 further includes an emission waveguide 118. Specifically, the transmitting waveguide 118 is embedded in the cladding 111, and has a refractive index greater than that of the cladding 111, so as to form a structure with the cladding 111 for stable transmission of the optical signal. The launch waveguide 118 may be made of silicon nitride having a refractive index greater than that of the cladding 111; of course, in other embodiments, the transmitting waveguide 118 may be made of other materials having a refractive index greater than that of the cladding 111, such as silicon. The launch waveguide 118 extends along the first predetermined direction XX and includes a third end and a fourth end opposite to each other; the third terminal is used for receiving the detection signal, and the fourth terminal is used for outputting the detection signal; the detection signal is used for detecting a target object. Along the second preset direction YY, the transmitting waveguide 118 is located on the same side of each receiving waveguide 112, and the first receiving waveguide 113 is located between the transmitting waveguide 118 and the second receiving waveguide 114. The fourth end of the transmitting waveguide 118 and the first end of the receiving waveguide 112 are located at the same end of the optical chip 11 and are disposed opposite to each other along the second predetermined direction YY. After the laser radar generating source optical signal is split into a detection signal and a local oscillation signal, the detection signal is received by the transmitting waveguide 118, and the detection signal is transmitted to the target object through the transmitting waveguide 118; the local oscillation signal is transmitted to the photodetection module 115. In this embodiment, the optical chip 11 adopts a mode of integrating the transmitting waveguide 118 and the receiving waveguide 112, and further can omit a light splitting device such as a light circulator or a polarization beam splitter prism by controlling the distance between the transmitting waveguide 118 and the receiving waveguide 112 to be smaller.

Further, the optical chip module 10 further includes a light splitting module 13. With continued reference to fig. 1, the optical splitting module 13 is configured to receive a source optical signal and split the source optical signal into a detection signal and a plurality of local oscillation signals, where the detection signal is used to detect a target object, and each of the optical detection modules 115 is configured to receive a local oscillation signal, and the optical splitting module 13 may include one or more optical splitters. In this embodiment, the spectroscopic module 13 is integrated with the optical chip 11. It should be understood that, in other embodiments of the application, the optical splitting module 13 may be separated from the optical chip 11 as shown in fig. 6, which is not limited in this application.

To facilitate calibration of the source light signal generated by the light source module 20 within the lidar, the optical chip 11 also includes a nonlinear calibration module 119. Specifically, the nonlinear calibration module 119 includes a first optical splitter 119a, a first delay line 119b, and a photodetection assembly 119c. The first optical splitter 119a is configured to receive the local oscillation signal and split the local oscillation signal into a first optical signal and a second optical signal. One input end of the photoelectric detection component 119c is connected with one output end of the first optical splitter 119a through a first delay line 119b, and the other input end is directly connected with the other output end of the first optical splitter 119a without passing through the delay line, so that the optical paths of the first optical signal and the second optical signal are different. The photoelectric detection component 119c is configured to receive the first optical signal and the second optical signal, and generate a second beat signal; the second beat signal is a signal with the frequency being the difference between the instantaneous frequencies of the first optical signal and the second optical signal, and the linearity of the source optical signal can be calibrated according to the second beat signal, so that the linearity of the source optical signal meets the requirement.

Specifically, the photo-detection assembly 119c may have substantially the same configuration as the photo-detection module 115 described above, for example, the photo-detection assembly 119c may include a mixer 115a and a balance photo-detector 115b, which are not described herein.

In summary, the optical chip module 10 provided in the embodiment of the present application includes an optical chip 11 and an optical modulation module 12. The optical tuning module 12 is disposed upstream of the optical path of at least one photo-detection module 115 in the optical chip 11, and the optical tuning module 12 is configured to receive one of the local oscillation signal or the echo signal, and perform frequency shift and/or delay processing to reduce frequency values of the first signal portion and the second signal portion of the first beat frequency signal generated by the photo-detection module 115. Therefore, the optical chip module 10 can improve the current situation that the ADC sampling rate adopted in the laser radar in the related art is higher.

In a second aspect, as shown in fig. 1, 6 and 8, the present application further provides a lidar, where the lidar includes a light source module 20 and an optical chip module 10 according to any of the above embodiments.

Wherein the light source module 20 is used for generating a source light signal. The light splitting module 13 of the optical chip module 10 is configured to receive the source optical signal and split the source optical signal into a detection signal and a plurality of local oscillation signals; the detection signals are used for detecting a target object, and each photoelectric detection module 115 is used for receiving a local oscillation signal to generate a first beat frequency signal according to the received local oscillation signal and echo signal. Wherein the beam-splitting module 13 may comprise one or more beam splitters.

In an embodiment of the present application, the light source module 20 includes a light source assembly 21 and a power adjustment assembly 22; the light source assembly 21 is used for generating an initial laser signal; the power adjustment assembly 22 is configured to receive the initial laser signal and output a source optical signal having a constant power.

Specifically, the light source assembly 21 is configured to generate an initial laser signal and to modulate the frequency of the generated initial laser signal to output a frequency-modulated initial laser signal. With continued reference to fig. 9, in one embodiment of the present application, the light source assembly 21 includes a laser for generating an initial laser signal and a frequency modulation driving circuit; the frequency modulation driving circuit is used for modulating the frequency of an initial laser signal generated by the laser; the frequency modulation process is realized by controlling the working temperature of the laser and changing the driving current of the laser.

It should be noted that, the actual frequency modulation process of the initial laser signal may not only cause the frequency variation of the initial laser signal, but also cause the power fluctuation of the initial laser signal; if the laser emission of the power generation waveguide is directly detected, the intensity fluctuation of the first beat signal formed by the initial laser signal can be caused, and the detection result of the laser radar is affected. As shown in fig. 10, which shows a time domain waveform diagram of a first beat signal when power adjustment is performed, taking a modulation waveform of an initial laser signal as a triangular wave linear frequency modulation as an example, the beat signal has obvious amplitude modulation phenomenon; that is, the signal strengths of the beat signals are different at different moments, and at this time, the spectrum of the beat signals is widened, so that the distance resolution of the laser radar is reduced, and the accuracy of the detection result of the laser radar is affected.

In this application, as shown in fig. 11, fig. 11 is a time domain waveform diagram of a first beat frequency signal formed by a source optical signal, and the power of an initial laser signal can be adjusted by the power adjusting component 22, so that the source optical signal which meets the power requirement and has constant power can be output as required, thereby avoiding the amplitude modulation phenomenon caused by the power fluctuation of the initial laser signal, improving the detection precision of the laser radar, and selecting a specific value of the target output power according to the actual requirement.

In one embodiment of the present application, the power conditioning assembly 22 includes a power conditioning unit 221 and a power conditioning circuit 222. The power adjusting unit 221 is configured to receive the initial laser signal and adjust the power of the initial laser signal; the power adjustment circuit 222 is configured to provide an injection current or an injection voltage to the power adjustment unit 221, so that the power adjustment module performs power adjustment on the initial laser signal to output a source optical signal with a constant target output power.

Wherein the power conditioning unit 221 may include one or more power conditioners 122, the power conditioners 122 may be passive devices such as variable optical attenuators (Variable Optical Attenuator, VOA), and the power conditioners 122 may also be active devices such as amplifiers including semiconductor optical amplifiers (Semiconductor Optical Amplifier, SOA), erbium-doped fiber amplifiers (Erbium Doped Fiber Amplifier, EDFA), etc.; when the power regulator 122 is a passive device, no current source and temperature control are needed in the power regulation circuit 222, and when the first power regulator 122 is an active device, current source and temperature control are needed in the power regulation circuit 222 to ensure proper operation of the first power regulator 122. Taking the power regulator 122 in the power regulator unit 221 as an example of the VOA, the power level of the source optical signal output by the power regulator unit 221 may be adjusted by adjusting the power level of the output power of the power regulator 122 according to the magnitude of the injection current or/and the injection voltage applied to the power regulator 122.

Specifically, the power adjustment unit 221 includes a second power adjuster 221a, and in an embodiment of the present application, the second power adjuster 221a may adjust the power of the initial laser signal and directly output a source optical signal with a constant target output power.

It should be noted that, taking the power attenuation coefficient of the second power regulator 221a as an example, the smaller the injection current of the second power regulator 221a is, the smaller the power attenuation ratio of the second power regulator 221a is, and the larger the attenuation coefficient is; conversely, the larger the injection current of the second power regulator 221a, the larger the power decay ratio of the second power regulator 221a, and the smaller the decay coefficient, i.e., the power decay coefficient of the second power regulator 221a is related to the injection current of the second power regulator 221 a; here, the "attenuation coefficient" as referred to herein means a ratio of the output power of the power adjuster 122 to the input power of the power adjuster 122 after the power adjuster 122 attenuates or amplifies the laser light. Therefore, when the power of the initial laser signal to which the second power adjuster 221a is connected is determined, the power of the source optical signal output by the second power adjuster 221a can be adjusted by adjusting the magnitude of the injection current of the second power adjuster 221a by the power adjusting circuit 222.

It should be noted that, taking the power of the initial laser signal P1 and the power of the source optical signal P2 as examples, the power attenuation coefficient f=p2/P1 of the second power regulator 221a, the injection current i of the second power regulator 221a is adjusted by the power regulating circuit 222, and after obtaining a plurality of power attenuation coefficients F corresponding to the injection current i one by one, the association relation F (i) between the power attenuation coefficient of the power regulating unit 221 and the injection current can be determined. Further, taking the target output power of the power adjusting unit 221 as P0 as an example, in the case of determining the power of the initial laser signal, a required power attenuation coefficient may be calculated according to P0 and the power of the initial laser signal, and a target injection current required by the power adjusting unit 221 may be determined according to the required power attenuation coefficient and the association relation F (i), and the power adjusting unit 221 may be provided with the target injection current through the power adjusting circuit 222, so that the power adjusting unit 221 may output a source optical signal with a constant target output power.

As shown in fig. 9, in an embodiment of the present application, the power adjustment unit 221 may further include a second beam splitter 221b, where the second power adjuster 221a is configured to adjust the power of the initial laser signal and output a transition laser signal with constant power; the second beam splitter 221b is configured to perform beam splitting processing on the transition laser signal, and output a monitoring optical signal and a source optical signal with constant power; the power adjusting circuit 222 is configured to collect the monitoring optical signal, and the splitting ratio of the second splitter 221b is determined, so that the power of the source optical signal output by the power adjusting unit 221 can be monitored according to the power of the monitoring optical signal; of course, when the actual power of the source optical signal output by the power adjustment unit 221 has a large difference from the target output power, the power of the source optical signal output by the power adjustment unit 221 may be corrected according to the monitor optical signal so that the power of the source optical signal output by the power adjustment unit 221 is the target output power.

In an embodiment of the present application, the power adjustment circuit 222 includes a photodetector, a first analog-to-digital converter ADC1, and a first digital-to-analog converter DAC1; the photoelectric detector is used for converting the monitoring optical signal into a monitoring electric signal; the first analog-to-digital converter ADC1 is used for sampling the monitoring electrical signal, and the sampling of the first analog-to-digital converter ADC1 is essentially a process of converting an analog signal into a digital signal so as to obtain the power of the monitoring optical signal; the first digital-to-analog converter DAC1 is used to provide an injection current or injection voltage for the second power regulator 221 a.

In some embodiments of the present application, the laser radar further includes a first analog-to-digital conversion module 30, where the first analog-to-digital conversion module 30 is disposed in one-to-one correspondence with the photoelectric detection module 115, and is configured to sample the first beat signal and convert the first beat signal into a digital signal, so that the signal processing module obtains information of the target object according to the digital signal. The first analog-to-digital conversion module 30 may include a transimpedance amplifier (Trans-Impedance Amplifier, T1A) and an analog-to-digital converter (Analog to Digital Converter, ADC). The T1A is used for receiving a first beat signal, and can amplify the first beat signal so as to facilitate sampling of the ADC; the ADC is used for sampling the amplified first beat frequency signal, so that the frequency of the first beat frequency signal can be obtained.

In addition, the lidar further includes a second analog-to-digital conversion module 40, and the second analog-to-digital conversion module 40 may sample the second beat signal of the nonlinear calibration module 119. The second analog-to-digital conversion module 40 may have substantially the same configuration as the first analog-to-digital conversion module 30, and will not be described herein.

The laser radar can also improve the current situation that the ADC sampling rate adopted in the laser radar in the related art is high due to the above-mentioned optical chip 11.

In a third aspect, based on the above-mentioned lidar, the present application further provides a mobile device comprising a lidar as in any of the embodiments above. The movable equipment can be equipment such as vehicles, airplanes, sweeping robots, unmanned aerial vehicles, robots, boats and the like.

The above-mentioned optical chip 11 is included, so that the mobile device can also improve the current situation that the ADC sampling rate adopted by the laser radar in the mobile device in the related art is higher.

In a fourth aspect, the present application further provides an optical power adjustment method applied to the laser radar in any one of the foregoing embodiments. The light source module 20 of the laser radar includes a light source assembly 21 and a power adjustment assembly 22. The light source assembly 21 is used to generate an initial laser signal. The power conditioning assembly 22 includes a power conditioning unit 221 and a power conditioning circuit 222. The power adjusting unit 221 is configured to receive an initial laser signal; the power adjusting circuit 222 is configured to provide an injection current or an injection voltage to the power adjusting unit 221, so that the power adjusting unit 221 performs power adjustment on the initial laser signal to output a source optical signal with a constant target output power, thereby improving the current situation that the beat signal is easy to generate an amplitude modulation phenomenon when the laser is directly used for detection.

As shown in fig. 12, in an embodiment of the present application, the optical power adjustment method includes:

s11, determining the association relation between the power attenuation coefficient of the power adjusting unit 221 and the injection current.

It should be noted that, the power adjusting unit 221 includes the power adjuster 122, and the power-saving coefficient of the power adjusting unit 221 is substantially the power-saving coefficient of the power adjuster 122 in the power adjusting unit 221. Specifically, the smaller the injection current of the power regulator 122, the smaller the power decay ratio of the power regulator 122, and the larger the power decay coefficient; conversely, the greater the injection current of the power regulator 122, the greater the power decay ratio of the power regulator 122 and the smaller the power decay coefficient; that is, the power attenuation coefficient of the power regulator 122 is related to the injection current of the power regulator 122, and the power attenuation coefficient of the power regulator 122 corresponds to the injection current one-to-one. Therefore, by adjusting the injection current of the power adjuster 122 and the ratio of the output power and the input power of the power adjusting unit 221 by the power adjusting circuit 222, the correlation F (i) between the power attenuation coefficient F of the power adjusting unit 221 and the injection current i can be determined.

Taking the injection current as i1, the input power of the power adjustment unit 221 is P1 (i.e., the power P1 of the initial laser signal), and the output power of the power adjustment unit 221 is P2 (i.e., the power of the source optical signal is P2) as examples; the power attenuation coefficient f1=p2/P1 of the power adjusting unit 221 corresponds to the current i1. After the power adjustment circuit 222 adjusts the injection current i of the power adjuster 122 to obtain a plurality of power attenuation coefficients F corresponding to the injection current i one by one, the association relationship F (i) between the power attenuation coefficients F and the injection current of the power adjustment unit 221 can be determined.

S12, determining the target injection current i of the power adjustment unit 221 according to the input power Pin, the target output power Pout, and the association relation F (i) of the power adjustment unit 221.

The target output power Pout and the input power Pin satisfy the association relation F (i), pout=pin (t) ×f (i (t)); since the target output power is a constant value

Namely:

accordingly, the injection current i can be determined by the above-described relationship under the condition that the input power Pin of the power adjusting unit 221 (i.e., the output power of the laser), the desired target output power Pout, and the above-described relationship are known.

In addition, since the power adjusting unit 221 may have a certain power loss ratio in a circuit other than the power adjuster 122, the power loss ratio α may be obtained first and then corrected by combining the above formulas. Specifically, pout=pin (t) ×α×f (i (t)); the injection current can thus be obtained by the following formula:

s13, the target injection current is injected into the power adjustment unit 221.

When the target injection current is determined, the power adjusting unit 221 may be provided with the target injection current by the power adjusting circuit 222, that is, the power adjusting unit 221 may output a source light signal with a constant target output power.

As shown in fig. 13, in another embodiment of the present application, the optical power adjustment method includes:

s21, determining the association relation between the power attenuation coefficient of the power adjusting unit 221 and the injection voltage;

it should be noted that, the power adjusting unit 221 includes the power adjuster 122, and the power-saving coefficient of the power adjusting unit 221 is substantially the power-saving coefficient of the power adjuster 122 in the power adjusting unit 221. Specifically, the smaller the injection voltage of the power regulator 122, the smaller the power decay ratio of the power regulator 122, and the larger the power decay coefficient; conversely, the greater the injection voltage of the power regulator 122, the greater the power decay ratio of the power regulator 122 and the smaller the power decay coefficient; that is, the power attenuation coefficient of the power regulator 122 is related to the injection voltage of the power regulator 122, and the power attenuation coefficient of the power regulator 122 corresponds to the injection voltage one by one. Therefore, by adjusting the injection voltage of the power regulator 122 and the ratio of the output power and the input power of the power regulating unit 221 by the power regulating circuit 222, the correlation between the power attenuation coefficient of the power regulating unit 221 and the injection voltage can be determined.

Taking the injection voltage v1, the input power of the power adjustment unit 221 is P1 (i.e., the power P1 of the initial laser signal), and the output power of the power adjustment unit 221 is P2 (i.e., the power of the source optical signal is P2) as examples; the power attenuation coefficient f1=p2/P1 of the power adjusting unit 221 corresponds to the injection voltage v1. After the injection voltage v of the power regulator 122 is adjusted by the power regulating circuit 222 to obtain a plurality of power attenuation coefficients F corresponding to the injection voltage v one by one, the association relationship F (v) between the power attenuation coefficients F of the power regulating unit 221 and the injection voltage v can be determined.

S22, determining the target injection voltage v of the power adjusting unit 221 according to the input power Pin, the target output power Pout, and the association relation F (v) of the power adjusting unit 221.

The target output power Pout and the input power Pin, and the above association relation F (v) are satisfied, pout=pin (t) ×f (v (t)); since the target output power is a constant value

Namely:

accordingly, the injection voltage v can be determined by the above-described relationship under the condition that the input power Pin of the power adjusting unit 221 (i.e., the output power of the laser), the desired target output power Pout, and the above-described relationship are known.

s23, the target injection voltage is injected into the power adjustment unit 221.

When the target injection voltage is determined, the power adjusting unit 221 may be provided with the target injection voltage by the power adjusting circuit 222, that is, the power adjusting unit 221 may output a source light signal with a constant target output power.

In the embodiments shown in fig. 12 and fig. 13, the power of the laser output by the laser is adjusted by the power adjusting unit 221, so as to realize detection by the source optical signal with constant power.

The foregoing description of the preferred embodiment of the present invention is not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims

1. An optical chip module, characterized by including optical chip and optical modulation module, optical chip includes:

a cladding layer;

the receiving waveguides are embedded in the cladding, extend along a first preset direction and are provided with a first end and a second end which are opposite to each other, the first end is used for receiving echo signals, the receiving waveguides are arranged at intervals along a second preset direction, and the second preset direction is intersected with the first preset direction; and

the photoelectric detection modules are arranged in one-to-one correspondence with the receiving waveguides, and are used for receiving local oscillation signals and echo signals output through the receiving waveguides and generating first beat signals, wherein the first beat signals comprise first signal parts with constant frequency and second signal parts with constant frequency;

The optical path upstream of at least one photoelectric detection module is provided with an optical modulation module, and the optical modulation module is used for receiving one of the local oscillation signals or the echo signals and performing frequency shift and/or delay processing so as to reduce the maximum value of the frequency values of the first signal part and the second signal part of the first beat frequency signals generated by the photoelectric detection module.

2. The optical chip module of claim 1, wherein the optical modulation module comprises a frequency shifter;

the frequency shifter is used for receiving the local oscillation signal and performing frequency shifting processing on the local oscillation signal so as to reduce the maximum value of the frequency values of the first signal part and the second signal part of the first beat frequency signal generated by the photoelectric detection module.

3. The optical chip module according to claim 2, wherein the frequency shifter is disposed on the cladding.

4. The optical chip module of claim 2, wherein each of the receiving waveguides is divided into a first receiving waveguide and a second receiving waveguide, and all of the second receiving waveguides are located on the same side of the first receiving waveguide along the second predetermined direction;

each photoelectric detection module is divided into a first photoelectric detection module and a second photoelectric detection module, the first photoelectric detection module is arranged corresponding to the first receiving waveguide, and the second photoelectric detection module is arranged corresponding to the second receiving waveguide;

The optical modulation modules are in one-to-one correspondence with the second photoelectric detection modules, are arranged on the upstream of the optical path of the second photoelectric detection modules, and are used for receiving one of the local oscillation signals or the echo signals and performing frequency shift processing so as to reduce the frequency values of the first signal part and the second signal part of the first beat frequency signals generated by the photoelectric detection modules.

5. The optical chip module of claim 4, wherein the optical chip module comprises two or more of the second receiving waveguides;

and along the direction that the first receiving waveguide points to the second receiving waveguide, the frequency shift amount of the frequency shifter corresponding to each second receiving waveguide gradually becomes larger.

6. The optical chip module of claim 4, wherein the optical chip module comprises N of the second receiving waveguides, wherein N is an integer greater than or equal to 1;

the detection distance of the first receiving waveguide is 0-R ₁ ，

Wherein c is the flying speed of light in air, K is the sweep slope of the local oscillation signal;

along the first receiving waveguideThe detection distance of the Nth second receiving waveguide pointing to the direction of the second receiving waveguide is R _N ～(R _N +R ₁ ) Wherein R is _N ＝N*R ₁ The frequency shifter corresponding to the Nth second receiving waveguide is configured to perform frequency shifting processing on the local oscillation signal, so that the upper sweep frequency signal of the local oscillation signal is reduced by a first frequency n×f ₂ And increasing the first frequency n×f of the down-swept frequency signal of the local oscillation signal ₂ ；

The optical chip module meets the following conditions:

7. the optical chip module of claim 1, wherein the optical modulation module comprises a delay unit;

the delay unit is used for receiving the local oscillation signal and carrying out delay processing on the local oscillation signal so as to reduce the frequency value of the first signal part and the second signal part generated by the photoelectric detection module.

8. The optical chip module of claim 7, wherein the delay element is located outside the optical chip.

9. The optical chip module of claim 7, wherein each of the receiving waveguides is divided into a first receiving waveguide and a second receiving waveguide, and all of the second receiving waveguides are located on the same side of the first receiving waveguide along the second predetermined direction;

The optical modulation modules are in one-to-one correspondence with the second photoelectric detection modules, are arranged on the upstream of the optical path of the second photoelectric detection modules, and are used for receiving the local oscillator signals and performing delay processing so as to reduce the frequency values of the first signal part and the second signal part of the first beat frequency signals generated by the photoelectric detection modules.

10. The optical chip module of claim 9, wherein the optical chip module comprises two or more of the second receiving waveguides;

and along the direction that the first receiving waveguide points to the second receiving waveguide, the delay amount of the delay unit corresponding to each second receiving waveguide gradually becomes larger.

11. The optical chip module of claim 9, wherein the optical chip module comprises N second receiving waveguides, wherein N is an integer greater than or equal to 1;

the detection distance of the first receiving waveguide is 0-R ₁ ，

Wherein c is the flying speed of light in air;

along the direction that the first receiving waveguide points to the second receiving waveguide, the detection distance of the Nth second receiving waveguide is R _N ～(R _N +R ₁ ) Wherein R is _N ＝N*R ₁ The delay unit corresponding to the nth receiving waveguide is configured to delay the local oscillation signal by n×t ₂ ；

The optical chip module meets the following conditions:

12. the optical chip module of claim 1, wherein the optical chip further comprises an emission waveguide;

the transmitting waveguide is located at the same side of each receiving waveguide along the second preset direction, the transmitting waveguide comprises a third end and a fourth end which are opposite to each other, the third end is used for receiving a detection signal, the fourth end is used for outputting the detection signal, and the fourth end and the first end are opposite to each other along the second preset direction;

wherein the detection signal is used for detecting a target object.

13. The optical chip module of claim 1, wherein the optical chip further comprises a nonlinear calibration module comprising:

the first optical splitter is used for receiving the local oscillation signal and splitting the local oscillation signal into a first optical signal and a second optical signal;

a first delay line; and

and one input end of the photoelectric detection component is connected with one output end of the first optical splitter through the first delay line, and the other input end of the photoelectric detection component is connected with the other output end of the first optical splitter so that the optical path lengths of the first optical signal and the second optical signal are different.

14. The optical chip module according to any one of claims 1 to 13, further comprising:

the optical chip module is used for receiving the light source signals output by the light source modules outside the optical chip module, and splitting the light source signals into detection signals and a plurality of local oscillation signals, wherein the detection signals are used for detecting target objects, and each photoelectric detection module is used for receiving one local oscillation signal.

15. The optical chip module of claim 2, wherein the frequency shifter is configured to shift the local oscillator signal to decrease an upper sweep signal of the local oscillator signal by a predetermined frequency and to increase a lower sweep signal of the local oscillator signal by the predetermined frequency.

16. A lidar, wherein the lidar is a frequency modulated continuous wave lidar, the lidar comprising:

the light source module is used for generating a source light signal; and

the optical chip module of any one of claims 1 to 15.

17. The lidar of claim 16, wherein the light source module comprises a light source assembly and a power adjustment assembly;

the light source component is used for generating an initial laser signal;

The power adjusting component is used for receiving the initial laser signal and outputting the source light signal with constant power.

18. A mobile device comprising a lidar according to claim 16 or 17.

19. An optical power adjustment method, applied to the laser radar as claimed in claim 16, wherein the light source module includes a light source assembly and a power adjustment assembly, the light source assembly is used for generating an initial laser signal, the power adjustment assembly includes a power adjustment unit and a power adjustment circuit, the power adjustment unit is used for receiving the initial laser signal, the power adjustment circuit is used for providing an injection current or an injection voltage for the power adjustment unit, so that the power adjustment unit performs power adjustment on the initial laser signal to output a source optical signal with constant target output power;

the optical power adjusting method comprises the following steps:

determining the association relation between the power attenuation coefficient of the power regulating unit and the injection current;

determining a target injection current of the power regulating unit according to the input power, the target output power and the association relation of the power regulating unit; and

Injecting the target injection current into the power conditioning unit;

or alternatively, the process may be performed,

the optical power adjusting method comprises the following steps:

determining the association relation between the power attenuation coefficient of the power regulating unit and the injection voltage;

determining a target injection voltage of the power regulating unit according to the input power, the target output power and the association relation of the power regulating unit; and

the target injection voltage is injected into the power conditioning unit.