WO2023098296A1

WO2023098296A1 - Apparatus for locking frequency modulation bandwidth of frequency-modulated continuous wave laser, and laser radar device

Info

Publication number: WO2023098296A1
Application number: PCT/CN2022/124399
Authority: WO
Inventors: 代西明; 陈海明
Original assignee: 北京万集科技股份有限公司
Priority date: 2021-11-30
Filing date: 2022-10-10
Publication date: 2023-06-08
Also published as: CN116203536A

Abstract

An apparatus for locking a frequency modulation bandwidth of a frequency-modulated continuous wave laser, and a laser radar device, which belong to the technical field of laser radars. The apparatus (100) for locking a frequency modulation bandwidth of a frequency-modulated continuous wave laser comprises a laser (10), a laser driving circuit (20), a photoelectric conversion circuit (30), a signal comparison circuit (40), a pre-correction signal generation circuit (50) and a multiplication circuit (60). By using the photoelectric conversion circuit (30), the signal comparison circuit (40), the multiplication circuit (60) and the pre-correction signal generation circuit (50), an output current of the laser driving circuit (20) is controlled, such that a negative feedback adjustment of a driving current of the laser (10) can be realized; and the bandwidth of the laser (10) is locked to a preset bandwidth corresponding to a preset reference electrical signal, and a distance measurement apparatus implements distance measurement and speed measurement according to an optical signal after the negative feedback adjustment, such that the precision and accuracy of distance measurement are improved.

Description

Frequency modulation continuous wave laser frequency modulation bandwidth locking device and laser radar equipment

This application claims the priority of the Chinese patent application with the application number 202111452475.0 and the title of the invention "Frequency Modulation Continuous Wave Laser Frequency Modulation Bandwidth Locking Device and LiDAR Equipment" filed at the China Patent Office on November 30, 2021, the entire contents of which Incorporated in this application by reference.

technical field

The application belongs to the technical field of laser radar, and in particular relates to a frequency modulation continuous wave laser frequency modulation bandwidth locking device and laser radar equipment.

Background technique

Frequency-modulated continuous wave laser ranging can realize high-precision ranging measurement, and it has very good prospects in lidar ranging and speed measurement.

Among them, the precision and accuracy of frequency modulation continuous wave laser ranging depends on the frequency modulation bandwidth, and the frequency modulation bandwidth depends on the amplitude and frequency of the modulation signal, that is, the driving current of the laser. When the frequency is determined, the bandwidth is only related to the amplitude of the modulation signal Correlation, the accuracy and stability of the driving current amplitude determine the accuracy and stability of the final ranging.

In the production process, due to differences in electronic devices, the amplitude of the driving current will be different, which leads to different modulation bandwidths for each device, but it cannot be adjusted accurately. Similarly, different batches of lasers or different manufacturers There will also be differences between different lasers, resulting in different bandwidths for the same drive current amplitude.

In addition, in the actual use process, different environmental conditions, especially different temperature conditions, will also change the response bandwidth of the laser, which will eventually cause the accuracy and accuracy of laser ranging to fail to meet the requirements.

technical problem

The purpose of this application is to provide a frequency modulation continuous wave laser frequency modulation bandwidth locking device, which aims to realize adaptive adjustment of the amplitude of the driving current of the laser, thereby locking the bandwidth and improving the precision and accuracy of laser ranging.

technical solution

In order to solve the above technical problems, the technical solution adopted in the embodiment of the present application is:

The first aspect of the embodiment of the present application proposes a frequency modulation continuous wave laser frequency modulation bandwidth locking device, including:

a laser, the laser is triggered by the current driving current to send out a chirp optical signal;

A laser drive circuit connected to the laser, configured to be triggered by a triangular wave modulation signal to output a drive current of a corresponding magnitude to the laser;

A photoelectric conversion circuit, the photoelectric conversion circuit performs photoelectric conversion on the chirp optical signal currently emitted by the laser, and outputs an electrical signal whose frequency is positively correlated with the frequency of the chirp optical signal;

A signal comparison circuit connected to the photoelectric conversion circuit, the signal comparison circuit is used to compare the electrical signal output by the photoelectric conversion circuit with a preset reference electrical signal, and output a signal that is equal to the frequency of the electrical signal Negatively correlated scaling signals;

A pre-correction signal generating circuit for outputting a triangular wave reference modulation signal;

a multiplication circuit respectively connected to the signal comparison circuit, the pre-correction signal generation circuit and the laser drive circuit, the multiplication circuit is used to multiply the triangular wave reference modulation signal and the scaling signal, and Outputting the amplitude-scaled triangular wave modulation signal to the laser drive circuit, so as to perform negative feedback regulation on the drive current output by the laser drive circuit.

Optionally, the laser drive circuit enters an initial steady state after being initially powered on, and correspondingly outputs an initial drive current to drive the laser to emit a chirp optical signal.

Optionally, the photoelectric conversion circuit includes:

A first optical splitter for optical splitting output, the first optical splitter is used to receive the chirp optical signal currently emitted by the laser and split the optical signal through two output terminals;

A delay fiber for signal delay output, the first end of the delay fiber is connected to the first output end of the first optical splitter;

A balanced detector for photoelectric conversion, the first input end of the balanced detector is connected to the second output end of the first optical splitter, the second input end of the balanced detector is connected to the delay optical fiber The second end is connected, and the output end of the balanced detector constitutes the signal output end of the photoelectric conversion circuit.

Optionally, the balanced detector is an unbalanced Mach-Zehnder interferometer.

Optionally, the photoelectric conversion circuit also includes:

An optical mixer for frequency mixing, the first input end of the optical mixer is connected to the second output end of the first optical splitter, the second input end of the optical mixer is connected to the delay When the second end of the optical fiber is connected, the output end of the optical mixer is connected to the input end of the balanced detector, and the output end of the balanced detector constitutes the signal output end of the photoelectric conversion circuit.

Optionally, the frequency modulation continuous wave laser frequency modulation bandwidth locking device further includes:

A second optical splitter connected to the laser and the photoelectric conversion circuit, the second optical splitter splits and outputs the chirp optical signal currently emitted by the laser, and sends it to the photoelectric conversion circuit and distance measuring circuit respectively device.

Optionally, the optical paths among the laser, the first optical splitter, the second optical splitter, the time-delay optical fiber, the optical mixer, and the balanced detector are connected by optical fibers.

Optionally, the signal comparison circuit includes:

active crystal oscillator;

A frequency and phase detector respectively connected to the photoelectric conversion circuit, the active crystal oscillator and the multiplication circuit.

Optionally, the FM bandwidth is:

B=(Fc*T)/2t;

Fc is the crystal oscillator frequency, t is the delay time of the delay fiber, and T is the frequency modulation period.

A filter circuit connected to the signal comparison circuit and the multiplication circuit respectively, the filter circuit is used for filtering the scaling signal.

Optionally, the filter circuit includes a loop filter.

Optionally, the multiplication circuit includes a multiplier.

Optionally, the laser is a distributed feedback laser.

The second aspect of the embodiments of the present application provides a laser radar device, which includes the frequency modulation continuous wave laser frequency modulation bandwidth locking device as described in any one of the above embodiments.

Optionally, the lidar device further includes a distance measuring device, and the distance measuring device is correspondingly connected to the frequency modulation continuous wave laser frequency modulation bandwidth locking device.

Beneficial effect

The above-mentioned frequency modulation continuous wave laser frequency modulation bandwidth locking device realizes the output current control of the laser drive circuit by using a photoelectric conversion circuit, a signal comparison circuit, a multiplication circuit and a pre-correction signal generation circuit, thereby realizing the negative feedback regulation of the drive current of the laser, The bandwidth of the laser is locked to the preset bandwidth corresponding to the preset reference electrical signal, and the distance measuring device realizes distance measurement and speed measurement according to the optical signal adjusted by negative feedback, and improves the precision and accuracy of laser distance measurement.

It can be understood that, for the beneficial effects of the above-mentioned second aspect, reference may be made to the relevant description in the above-mentioned first aspect, and details are not repeated here.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings that need to be used in the descriptions of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only for the present application For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without creative effort.

Fig. 1 is the first structure schematic diagram of the FM continuous wave laser FM bandwidth locking device provided by the embodiment of the present application;

FIG. 2 is a schematic diagram of the second structure of the frequency modulation continuous wave laser frequency modulation bandwidth locking device provided by the embodiment of the present application;

FIG. 3 is a schematic diagram of the third structure of the frequency modulation continuous wave laser frequency modulation bandwidth locking device provided by the embodiment of the present application;

Fig. 4 is a schematic diagram of the fourth structure of the frequency modulation continuous wave laser frequency modulation bandwidth locking device provided by the embodiment of the present application;

FIG. 5 is a schematic diagram of the fifth structure of the frequency modulation continuous wave laser frequency modulation bandwidth locking device provided by the embodiment of the present application;

Fig. 6 is a schematic diagram of the sixth structure of the frequency modulation continuous wave laser frequency modulation bandwidth locking device provided by the embodiment of the present application;

FIG. 7 is a schematic structural diagram of a lidar device provided by an embodiment of the present application.

Embodiments of the present invention

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present application, "plurality" means two or more, unless otherwise specifically defined.

The first aspect of the embodiments of the present application proposes a frequency modulation continuous wave laser frequency modulation bandwidth locking device 100 .

As shown in Figure 1, in this embodiment, the FM continuous wave laser FM bandwidth locking device 100 includes:

A laser 10, the laser 10 is triggered by the current driving current to emit a chirp optical signal;

The laser drive circuit 20 connected to the laser 10 is used to be triggered by the triangular wave modulation signal to output a corresponding driving current to the laser 10;

A photoelectric conversion circuit 30, the photoelectric conversion circuit 30 performs photoelectric conversion on the chirp optical signal currently emitted by the laser 10, and outputs an electrical signal whose frequency is positively correlated with the frequency of the chirp optical signal;

A signal comparison circuit 40 connected to the photoelectric conversion circuit 30, the signal comparison circuit 40 is used to compare the electrical signal output by the photoelectric conversion circuit 30 with a preset reference electrical signal, and output a signal that is negatively correlated with the frequency of the electrical signal scaling signal;

A pre-correction signal generating circuit 50 for outputting a triangular wave reference modulation signal;

The multiplication circuit 60 connected to the signal comparison circuit 40, the pre-correction signal generation circuit 50 and the laser drive circuit 20 respectively, the multiplication circuit 60 is used to multiply the triangular wave reference modulation signal and the scaling signal, and output the triangular wave after amplitude scaling The modulation signal is sent to the laser driving circuit 20 to perform negative feedback regulation on the driving current output by the laser driving circuit 20 .

In this embodiment, the frequency modulation continuous wave laser frequency modulation bandwidth locking device 100 quickly enters the initial steady state after being initially powered on, and the laser driving circuit 20 correspondingly outputs an initial driving current to drive the laser 10 to work. The laser 10 emits a chirp optical signal, and the measurement The distance device 200 obtains the optical signal reflected by the object to be measured through the laser receiving component, and determines the distance and speed of the object to be measured according to the frequency difference between the transmission and reception of the optical signal, so as to realize the laser radar ranging function, wherein the distance measuring device 200 The type is not limited, and it can be composed of optical receiving elements, photoelectric converters, power amplifiers, controllers and other components.

At the same time, the chirp optical signal is also input to the photoelectric conversion circuit 30 through an optical fiber to perform positive proportional photoelectric conversion, that is, the frequency of the converted output electrical signal is positively correlated with the frequency of the chirp optical signal sent by the current laser 10, and the electrical signal output To the signal comparison circuit 40 for signal comparison, wherein the size of the preset reference electrical signal in the signal comparison circuit 40 corresponds to the preset bandwidth setting, and the electrical signal is compared with the preset reference electrical signal, which is equivalent to the bandwidth of the current optical signal and The preset bandwidth is compared, and the scaling ratio signal after the signal comparison is negatively correlated with the electrical signal, that is, the bandwidth negative feedback detection and adjustment of the electrical signal, chirp optical signal and optical signal is realized, and the output scaling ratio signal and the triangular wave reference modulation signal Perform a multiplication operation, so that the triangular wave modulation signal received by the laser drive circuit 20 is a triangular wave modulation signal after negative feedback adjustment, and output the drive current corresponding to the negative feedback adjustment to the laser 10, so that the response bandwidth adjustment of the laser 10 is equal to the preset Set the bandwidth.

For example, when the bandwidth of the optical signal output by the laser 10 is relatively large, its frequency is relatively large. At this time, the frequency of the electrical signal after photoelectric conversion is relatively large, and the scaling ratio signal after comparison with the signal of the preset reference electrical signal becomes smaller. , the triangular wave modulation signal after the multiplication of the scaling signal and the triangular wave reference modulation signal becomes smaller, thereby controlling the drive current output by the laser drive circuit 20 to become smaller, so that the bandwidth of the laser 10 becomes smaller, realizing bandwidth negative feedback adjustment, and finally locking to the preset bandwidth.

Similarly, when the bandwidth of the optical signal output by the laser 10 is small, its frequency is small. At this time, the frequency of the electrical signal after photoelectric conversion is small, and the scaling ratio signal after comparison with the signal of the preset reference electrical signal becomes larger , the triangular wave modulation signal after the multiplication of the scaling signal and the triangular wave reference modulation signal becomes larger, thereby controlling the drive current output by the laser drive circuit 20 to become larger, so that the bandwidth of the laser 10 becomes larger, and the negative feedback adjustment of the bandwidth is realized, and finally locked to the preset bandwidth.

At the same time, when faced with different lasers 10, or when the response bandwidth of the same laser 10 in different environments changes, through negative feedback adjustment, the final response bandwidth is locked to the preset bandwidth, and the distance measuring device 200 according to the modulated optical signal Realize laser distance measurement and speed measurement, and improve the precision and accuracy of laser distance measurement.

Wherein, the preset reference electrical signal can be generated internally by the signal comparison circuit 40, or obtained from a corresponding external signal source, and the specific obtaining method is not limited.

The laser 10 can be different types of lasers 10, such as FP (Fabry-perot, Fabry-Perot) laser 10, DFB (Distributed Feedback Laser, distributed feedback laser) laser 10, etc. Optionally, the laser 10 is a DFB laser 10. The DFB laser 10 can also maintain single-mode characteristics during high-speed modulation, and can be used for long-distance transmission.

The photoelectric conversion circuit 30 can be formed by using a corresponding optical path structure, such as a balanced detector 33, an optical mixer, etc., and the specific structure is not limited.

The laser driving circuit 20 may use a corresponding current source circuit, and similarly, the pre-correction signal generating circuit 50 may use a corresponding signal source circuit, and the specific structure is not limited.

The multiplication circuit 60 may adopt structures such as a multiplier 61 and a transistor. Optionally, as shown in FIG. 6 , the multiplication circuit 60 includes a multiplier 61 .

The signal comparison circuit 40 can adopt a corresponding frequency comparison circuit, such as a frequency and phase detector 42, a frequency detector and other structures. Optionally, as shown in FIG. 6, the signal comparison circuit 40 includes:

Active crystal oscillator 41;

A frequency and phase detector 42 connected to the photoelectric conversion circuit 30 , the active crystal oscillator 41 and the multiplication circuit 60 respectively.

In this embodiment, the active crystal oscillator 41 generates a preset reference electrical signal with a preset frequency, and the frequency and phase detector 42 generates a scaled signal proportional to the phase difference between the preset reference electrical signal and the electrical signal output by the photoelectric conversion circuit 30. The frequency and phase detector 42 corrects the difference between the two input signals in the loop to realize frequency locking.

In this embodiment, the output current control of the laser drive circuit 20 is realized by using the photoelectric conversion circuit 30, the signal comparison circuit 40, the multiplication circuit 60 and the pre-correction signal generation circuit 50, thereby realizing the negative feedback regulation of the drive current of the laser 10 , the bandwidth of the laser 10 is locked to the preset bandwidth corresponding to the preset reference electrical signal, and the distance measuring device 200 realizes distance measurement and speed measurement according to the optical signal adjusted by negative feedback, thereby improving the precision and accuracy of distance measurement.

As shown in FIG. 2, optionally, the photoelectric conversion circuit 30 includes:

A first optical splitter 31 for optical output, the first optical splitter 31 is used to receive the chirp optical signal currently emitted by the laser 10 and split the optical signal through two output terminals;

A delay fiber 32 for signal delay output, the first end of the delay fiber 32 is connected to the first output end of the first optical splitter 31;

A balance detector 33 for photoelectric conversion, the first input end of the balance detector 33 is connected with the second output end of the first beam splitter 31, the second input end of the balance detector 33 is connected with the second end of the delay fiber 32 The output end of the balance detector 33 constitutes the signal output end of the photoelectric conversion circuit 30 .

In this embodiment, after the chirp optical signal output by the laser 10 passes through the first optical splitter 31, one path is delayed and input to the first input end of the balance detector 33 through the delay fiber 32, and the other path is directly input to the balance detector 33 The second input terminal of the balanced detector 33 forms coherent light from the two input optical signals, and outputs a differential current signal to the signal comparison circuit 40. The output current of the balanced detector 33 changes as the frequency of the laser 10 changes, That is, the output current and the frequency of the laser 10 have a corresponding curve optical system. The balanced detector 33 is an unbalanced Mach-Zehnder interferometer.

Among them, the calculation relationship between crystal oscillator frequency and FM bandwidth is as follows:

Assuming that the crystal oscillator frequency is Fc, the delay time of the delay fiber 32 is t, the frequency modulation bandwidth is B, and the frequency modulation cycle is T, then there is

B=(Fc*T)/2t.

Therefore, the preset bandwidth can be set by changing the frequency of the crystal oscillator, and the frequency of the crystal oscillator is used as a reference frequency to realize locking of the preset bandwidth.

Further, as shown in FIG. 3, optionally, the photoelectric conversion circuit 30 further includes:

For the optical mixer 34 of frequency mixing, the first input end of optical mixer 34 is connected with the second output end of first optical splitter 31, the second input end of optical mixer 34 is connected with the delay fiber 32 The second end is connected, the output end of the optical mixer 34 is connected to the input end of the balanced detector 33 , and the output end of the balanced detector 33 constitutes the signal output end of the photoelectric conversion circuit 30 .

In this embodiment, the optical mixer 34 is used to realize the superposition of two optical signals to generate two beat frequency signals with a phase difference of 180 degrees. mode noise suppression.

Further, as shown in FIG. 4, optionally, the frequency modulation continuous wave laser frequency modulation bandwidth locking device 100 also includes:

The second optical splitter 70 connected to the laser 10 and the photoelectric conversion circuit 30 respectively. The second optical splitter 70 splits and outputs the chirp optical signal currently emitted by the laser 10 and sends it to the photoelectric conversion circuit 30 and the distance measuring device 200 respectively.

In this embodiment, the distance measuring device 200 obtains the optical signal output by the laser 10 through the second beam splitter 70, and determines the distance and speed of the object to be measured according to the optical signal adjusted by negative feedback, so as to realize accurate distance measurement.

Wherein, the optical paths among the laser 10 , the first optical splitter 31 , the second optical splitter 70 , the delay fiber 32 , the optical mixer 34 and the balance detector 33 are connected by optical fibers.

Further, as shown in FIG. 5 , in order to improve the accuracy of feedback adjustment, optionally, the frequency modulation continuous wave laser frequency modulation bandwidth locking device 100 also includes:

A filter circuit 80 connected to the signal comparison circuit 40 and the multiplication circuit 60 respectively, the filter circuit 80 is used to filter the scaling signal to filter the clutter generated therein, so as to output a filtered scaling signal to the multiplier circuit 60, thereby ensuring that the multiplication circuit 60 obtains an accurate scaling signal.

Wherein, the filter circuit 80 may adopt different filter structures, as shown in FIG. 6 , optionally, the filter circuit 80 includes a loop filter 81 , such as a 5th-order passive filter.

The second aspect of the embodiments of the present application provides a laser radar device, and the laser radar device includes the frequency modulation continuous wave laser frequency modulation bandwidth locking device 100 according to any one of the above embodiments.

In this embodiment, the laser radar device realizes the negative feedback regulation of the driving current of the laser 10 by using the frequency modulation continuous wave laser frequency modulation bandwidth locking device 100, and locks the bandwidth of the laser 10 to the preset bandwidth, and the distance measuring device 200 adjusts the frequency according to the negative feedback. The final optical signal realizes distance measurement and speed measurement, and improves the distance measurement precision and accuracy.

Wherein, the distance measuring device 200 can be set in the laser radar equipment, or can be arranged separately. Optionally, as shown in FIG. The device 100 is correspondingly connected, and the distance measuring device 200 performs laser distance measurement and speed measurement according to the optical signal output by the frequency modulation continuous wave laser frequency modulation bandwidth locking device 100, so as to realize accurate distance measurement.

The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still implement the foregoing embodiments Modifications to the technical solutions described in the examples, or equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the application, and should be included in the Within the protection scope of this application.

Claims

A frequency modulation continuous wave laser frequency modulation bandwidth locking device, including:

a laser, the laser is triggered by the current driving current to send out a chirp optical signal;

A laser drive circuit connected to the laser, configured to be triggered by a triangular wave modulation signal to output a drive current of a corresponding magnitude to the laser;

A photoelectric conversion circuit, the photoelectric conversion circuit performs photoelectric conversion on the chirp optical signal currently emitted by the laser, and outputs an electrical signal whose frequency is positively correlated with the frequency of the chirp optical signal;

A signal comparison circuit connected to the photoelectric conversion circuit, the signal comparison circuit is used to compare the electrical signal output by the photoelectric conversion circuit with a preset reference electrical signal, and output a signal that is equal to the frequency of the electrical signal Negatively correlated scaling signals;

A pre-correction signal generating circuit for outputting a triangular wave reference modulation signal;

a multiplication circuit respectively connected to the signal comparison circuit, the pre-correction signal generation circuit and the laser drive circuit, the multiplication circuit is used to multiply the triangular wave reference modulation signal and the scaling signal, and Outputting the amplitude-scaled triangular wave modulation signal to the laser drive circuit, so as to perform negative feedback regulation on the drive current output by the laser drive circuit.
The device for frequency modulation bandwidth locking of frequency modulation continuous wave laser according to claim 1, wherein the laser drive circuit enters an initial steady state after initial power-on, and correspondingly outputs an initial drive current to drive the laser to emit chirp optical signals.
Frequency modulation continuous wave laser frequency modulation bandwidth locking device as claimed in claim 1, wherein, described photoelectric conversion circuit comprises:

A first optical splitter for optical splitting output, the first optical splitter is used to receive the chirp optical signal currently emitted by the laser and split the optical signal through two output terminals;

A delay fiber for signal delay output, the first end of the delay fiber is connected to the first output end of the first optical splitter;

A balanced detector for photoelectric conversion, the first input end of the balanced detector is connected to the second output end of the first optical splitter, the second input end of the balanced detector is connected to the delay optical fiber The second end is connected, and the output end of the balanced detector constitutes the signal output end of the photoelectric conversion circuit.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device according to claim 3, wherein the balanced detector is an unbalanced Mach-Zehnder interferometer.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device according to claim 3, wherein the photoelectric conversion circuit further comprises:

An optical mixer for frequency mixing, the first input end of the optical mixer is connected to the second output end of the first optical splitter, the second input end of the optical mixer is connected to the delay When the second end of the optical fiber is connected, the output end of the optical mixer is connected to the input end of the balanced detector, and the output end of the balanced detector constitutes the signal output end of the photoelectric conversion circuit.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device as claimed in claim 5, wherein, the frequency modulation continuous wave laser frequency modulation bandwidth locking device further comprises:

A second optical splitter connected to the laser and the photoelectric conversion circuit, the second optical splitter splits and outputs the chirp optical signal currently emitted by the laser, and sends it to the photoelectric conversion circuit and distance measuring circuit respectively device.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device according to claim 6, wherein the laser, the first optical splitter, the second optical splitter, the time-delay optical fiber, the optical mixer and the The optical path between the balanced detectors is connected by optical fiber.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device as claimed in claim 6, wherein said signal comparison circuit comprises:

active crystal oscillator;

A frequency and phase detector respectively connected to the photoelectric conversion circuit, the active crystal oscillator and the multiplication circuit.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device as claimed in claim 8, wherein, the frequency modulation bandwidth is:

B=(Fc*T)/2t;

Fc is the crystal oscillator frequency, t is the delay time of the delay fiber, and T is the frequency modulation cycle.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device according to claim 1, wherein the frequency modulation continuous wave laser frequency modulation bandwidth locking device further comprises:

A filter circuit connected to the signal comparison circuit and the multiplication circuit respectively, the filter circuit is used for filtering the scaling signal.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device according to claim 10, wherein said filtering circuit comprises a loop filter.
The frequency modulation continuous wave laser frequency modulation bandwidth locking device according to claim 1, wherein said multiplication circuit comprises a multiplier.
The device for frequency modulation bandwidth locking of frequency modulation continuous wave laser according to claim 1, wherein the laser is a distributed feedback laser.
A laser radar device, comprising the device for frequency modulation bandwidth locking of frequency modulation continuous wave laser according to claim 1.
The laser radar device according to claim 14, wherein the laser radar device further comprises a distance measuring device, and the distance measuring device is correspondingly connected to the frequency modulation continuous wave laser frequency modulation bandwidth locking device.