Tunable laser fiber grating demodulator with high demodulation speed and demodulation method

Abstract

The application provides a tunable laser fiber grating demodulator with high demodulation speed and a demodulation method, to solve the technical problems of complex calibration trigger algorithm, long time consumption, low sensing precision and slow demodulation speed in the prior art. The demodulator comprises a data acquisition and processing unit, a computer, a frequency sweeping laser unit connected in sequence, and a first fiber coupler, an HCN gas absorption chamber, a second fiber coupler, two second photoelectric converters, a fiber splitter, N fiber loopers, N-way fiber grating sensors and N first photoelectric converters. The inlet end of the HCN gas absorption chamber is connected with the output end of the first fiber coupler, to absorb P fixed wavelength lights output by the first fiber coupler and output wavelength absorption lines. The outlet end is connected with the two second photoelectric converters through the second fiber coupler. The two second photoelectric converters are both used for converting the wavelength absorption lines into pulse signals, and are used as trigger signals and calibration signals respectively.

Description

TECHNICAL FIELD

[0001] The present application relates to a fiber grating demodulator, in particular to a tunable laser fiber grating demodulator with high demodulation speed and a demodulation method. BACKGROUND

[0002] The fiber grating is a new type of sensor capable of measuring various physical quantities, which has the characteristics of small volume, light weight, high precision, easy multiplexing, etc. The sensing method of the fiber grating is based on the detection of wavelength, which is independent of light intensity and has good shielding property to electromagnetic interference. Due to its high sensitivity and stable performance, the fiber grating has been widely used in civil construction, new energy vehicles, aerospace and other fields.

[0003] The key technology of the fiber grating demodulator is to reflect the change of external physical quantity by demodulating the movement of the center wavelength of the fiber grating. In some special sensing fields, it is necessary to demodulate the center wavelength of the fiber grating which changes at high speed. The current fiber grating demodulator is mainly based on the fiber grating demodulation of tunable laser. The demodulation speed and sensing accuracy of the fiber grating demodulation system based on tunable laser mainly depend on the linearity of the tunable laser sweep light and the accuracy of the trigger center wavelength acquisition signal, wherein the linearity of the tunable laser sweep light needs to be calibrated by the demodulation system.

[0004] At present, the method for calibrating the linearity of the tunable laser sweep light mainly includes adding a calibrated fiber grating string in the demodulation system to calibrate the trigger of the sweep light wavelength. This method needs to collect all the wavelength signals of the fiber grating string first, then find the center wavelength peak characteristic line in the collected signal, and finally extract and compare the center wavelength data. However, the whole calibration trigger algorithm in this method is complex, time-consuming, the fiber grating is easily affected by the external environment to cause center wavelength drift, which greatly reduces the sensing accuracy of the system, and the calibration time is also affected by the external environment to increase, thereby affecting the overall demodulation speed of the system. SUMMARY

[0005] The purpose of the present application is to solve the technical problems of the existing tunable laser fiber grating demodulator, such as complex calibration trigger algorithm, long time consumption, low sensing accuracy of the system and slow demodulation speed when calibrating the trigger of the sweep light wavelength, and to provide a tunable laser fiber grating demodulator with high demodulation speed and a demodulation method.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] A high demodulation speed tunable laser fiber grating demodulator, comprising a data acquisition and processing unit, a computer, a frequency sweeping laser unit, and a first fiber coupler, a fiber splitter, N fiber circulators, N fiber grating sensors and N first photoelectric converters connected in sequence; the frequency sweeping laser unit is used for outputting a frequency sweeping light signal, the output end of which is connected with the fiber splitter through the first fiber coupler, the fiber splitter divides the frequency sweeping light signal into N measurement lights which enter the N fiber grating sensors through the N fiber circulators respectively, the N fiber grating sensors reflect the measurement lights and enter the N first photoelectric converters through the fiber circulators respectively, and the first photoelectric converters convert the measurement light signals into measurement electric signals; the output ends of the N first photoelectric converters are connected with the input ends of the data acquisition and processing unit respectively, N=2 n , n=1, 2, 3, 4, 5; the special feature is that:

[0008] Further comprising an HCN gas absorption chamber, a second fiber coupler and two second photoelectric converters;

[0009] The input end of the HCN gas absorption chamber is connected with the output end of the first fiber coupler, and the output end of the HCN gas absorption chamber is connected with the two second photoelectric converters through the second fiber coupler respectively;

[0010] The HCN gas absorption chamber is used for absorbing P fixed wavelength lights output by the first fiber coupler and outputting wavelength absorption lines, wherein the wavelength intervals of the P fixed wavelength lights are equidistant;

[0011] The two second photoelectric converters are both used for converting the wavelength absorption lines output by the HCN gas absorption chamber into P pulse signals, one of which is used as a trigger signal for the data acquisition and processing unit to collect the center wavelength of the fiber grating, and the other of which is used as a calibration signal for the frequency sweeping laser unit;

[0012] The data acquisition and processing unit receives the trigger signal and collects the measurement electric signals output by each fiber grating sensor;

[0013] The computer performs linear calibration on the frequency sweeping light according to the calibration signal received by the data acquisition and processing unit, and demodulates the center wavelength of the measurement light reflected by each fiber grating sensor according to the calibrated frequency sweeping light signal corresponding to the measurement electric signal output by each fiber grating sensor after calibration.

[0014] Further, the data acquisition and processing unit comprises a signal processing circuit and a data acquisition card; the input end of the signal processing circuit is connected with the output end of the data acquisition card, and the output end of the signal processing circuit is connected with the input end of the computer; the output ends of the N first photoelectric converters are connected with the input ends of the data acquisition card respectively;

[0015] The sweep laser unit comprises a laser drive circuit and a tunable laser; an input end of the laser drive circuit is connected with an output end of a computer, and an output end of the laser drive circuit is connected with an input end of the tunable laser; the tunable laser is used for outputting a sweep optical signal, and an output end thereof is connected with an optical fiber splitter through a first optical fiber coupler.

[0016] Meanwhile, the application also provides a tunable laser fiber grating demodulation method with high demodulation speed, and the speciality of the tunable laser fiber grating demodulator with high demodulation speed lies in comprising the following steps:

[0017] S1, a linear sweep optical signal is outputted by the sweep laser unit, and is divided into two paths through the first optical fiber coupler, one path of which is used as reference light to enter the HCN gas absorption chamber, and the other path is used as measurement light to enter each optical fiber grating sensor through the optical fiber splitter and the optical fiber ring in sequence;

[0018] S2, P fixed wavelength lights in the reference light are absorbed by the HCN gas absorption chamber, and P wavelength absorption lines are outputted, which are divided into two paths through the second photoelectric converter, one path of which is converted into P pulse signals through a second photoelectric converter, and the P pulse signals are evenly divided into L wavelength intervals, and the first pulse signal of each wavelength interval is used as a trigger signal, and the other path is converted into P pulse signals through another second photoelectric converter, and the P pulse signals are evenly divided into L wavelength intervals, and each wavelength interval has M pulse signals, and the M pulse signals are used as calibration signals; meanwhile, after the measurement light is reflected by each optical fiber grating sensor, the center wavelength is converted into a measurement electrical signal through the optical fiber ring and the first photoelectric converter;

[0019] S3, after the calibration signals are collected by the data acquisition and processing unit, the sampling point number of each wavelength interval is calculated through the computer, the sampling point number of each wavelength interval is used as a linear calibration reference of the sweep light, the sweep light is linearly calibrated, and the sweep laser unit outputs the calibrated sweep optical signal;

[0020] S4, when the TTL high level converted by the trigger signal is received by the data acquisition and processing unit, the measurement electrical signal corresponding to the calibration signal in the corresponding wave band outputted by each optical fiber grating sensor is collected, and the center wavelength of the measurement light reflected by each optical fiber grating sensor is demodulated according to the calibrated sweep optical signal corresponding to the measurement electrical signal.

[0021] Further, the step S3 is specifically: after the data acquisition card in the data acquisition and processing unit collects the calibration signal, the computer data processing system calculates the sampling point number of each wavelength interval, judges whether the sampling point number of each wavelength interval is equal; if equal, no calibration is performed; if not equal, the sampling point number of the first wavelength interval is used as the linearity calibration reference of the sweep frequency light, the relationship between the sampling point and the wavelength is fitted in the form of quadratic sample curve fitting, the fitting function between the sampling point and the wavelength is obtained, and the sweep frequency light is linearly calibrated to control the tunable laser in the sweep frequency laser unit to output the calibrated sweep frequency light signal.

[0022] Further, in the step S1, the sweep frequency laser unit outputting the linear sweep frequency light signal is specifically: the computer sends the laser scanning digital signal to the laser drive circuit, the laser drive circuit controls the tunable laser to linearly sweep the light source according to the laser scanning digital signal, and the linear sweep frequency light signal is obtained.

[0023] The beneficial effects of the present application are:

[0024] 1. The present application provides a tunable laser fiber grating demodulator with high demodulation speed, wherein the HCN gas absorption chamber can not be affected by external environment interference, and can obtain an absolutely stable wavelength absorption line; the wavelength absorption line output by the HCN gas absorption chamber is converted into a pulse signal as a trigger signal and a calibration signal, the trigger and calibration precision is high and fast, and the demodulation speed of the tunable laser fiber grating demodulator is improved.

[0025] 2. The present application provides a tunable laser fiber grating demodulation method with high demodulation speed, the wavelength absorption line output by the HCN gas absorption chamber is converted into a trigger signal and a calibration signal by two second photoelectric converters, the calibration of the sweep frequency light signal can be completed at the same time when the fiber grating center wavelength signal is collected; the data acquisition trigger and the sweep frequency light linear calibration algorithm in the present application is simple and has high precision, the wavelength calibration trigger time is greatly shortened, and the demodulation speed of the demodulator is improved. In addition, when the data acquisition and processing unit receives the TTL high level converted by the trigger signal, the measurement electrical signal corresponding to the calibration signal of each fiber grating sensor is collected, the sampling time of the demodulator can be shortened, and the demodulation speed is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a structure schematic view of an embodiment of the present application, a tunable laser fiber grating demodulator with high demodulation speed;

[0027] Figure 2 It is a wavelength absorption line output by the HCN gas absorption chamber in the embodiment of the present application;

[0028] Figure 3 This is a schematic diagram of the trigger and calibration signals converted by the photoelectric converter from the wavelength absorption line output from the HCN gas absorption chamber in an embodiment of the present invention.

[0029] Icon labels:

[0030] 1-Computer, 2-Laser driver circuit, 3-Tunable laser, 4-First fiber optic coupler, 5-Signal processing circuit, 6-Data acquisition card, 7-First photoelectric converter, 8-HCN gas absorption chamber, 9-Fiber optic splitter, 10-Fiber optic circulator, 11-Fiber Bragg grating sensor, 12-Second photoelectric converter, 13-Data acquisition and processing unit, 14-Sweep laser unit, 15-Second fiber optic coupler. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] like Figure 1 As shown, the high demodulation speed tunable laser fiber Bragg grating demodulator includes a computer 1, a laser driving circuit 2, a tunable laser 3, a first fiber coupler 4, a signal processing circuit 5, a data acquisition card 6, two second photoelectric converters 12, a second fiber coupler 15, an HCN gas absorption chamber 8, a fiber optic splitter 9, N fiber optic circulators 10, N fiber Bragg grating sensors 11, and N first photoelectric converters 7. Specifically, the input terminal of signal processing circuit 5 is connected to the output terminal of data acquisition card 6, the output terminal of signal processing circuit 5 is connected to the input terminal of computer 1, the output terminal of computer 1 is connected to the input terminal of laser driver circuit 2, and the output terminal of laser driver circuit 2 is connected to the input terminal of tunable laser 3. Tunable laser 3 is used to output a swept-frequency optical signal, and its output terminal is connected to fiber optic splitter 9 through first fiber coupler 4. Fiber optic splitter 9 divides the swept-frequency optical signal into N measurement beams, which pass through N fiber optic circulators 10 and enter N fiber optic grating sensors 11. The N fiber optic grating sensors 11 reflect the measurement beams and then enter N first photoelectric converters 7 through each fiber optic circulator 10, converting the measurement optical signal into a measurement electrical signal. The output terminals of the N first photoelectric converters 7 are connected to the input terminal of data acquisition card 6, where N=2. n, n = 1, 2, 3, 4, 5, the inlet end of the HCN gas absorption chamber 8 is connected with the output end of the first optical fiber coupler 4, the outlet end of the HCN gas absorption chamber 8 is connected with the input end of the second optical fiber coupler 15, the two output ends of the second optical fiber coupler 15 are respectively connected with two second photoelectric transducers 12, the HCN gas absorption chamber 8 is used for absorbing P fixed wavelength lights of the swept frequency light output by the first optical fiber coupler 4 and outputting wavelength absorption lines, wherein the wavelength interval of the P fixed wavelength lights is equidistant, the two second photoelectric transducers 12 are both used for converting the wavelength absorption lines output by the HCN gas absorption chamber 8 into P pulse signals, one road is used as a trigger signal for collecting the center wavelength of the fiber grating by the data acquisition card 6, and the other road is used as a calibration signal for the tunable laser 3, the data acquisition card 6 receives the trigger signal and collects the measurement electric signals output by each fiber grating sensor 11, the computer 1 receives the calibration signal of the data acquisition card 6, linearly calibrates the swept frequency light, and demodulates the center wavelength of the measurement light reflected by each fiber grating sensor 11 according to the measurement electric signals output by each fiber grating sensor 11 and the calibrated swept frequency light signals corresponding to the measurement electric signals after calibration, in addition, it needs to be explained that the more P is, the faster the demodulation speed is and the higher the precision is, and P in the embodiment is 21.

[0033] The demodulation method steps of the tunable laser fiber grating demodulator with high demodulation speed in the application are specifically as follows:

[0034] S1, the computer 1 sends a laser scanner digital signal to the laser driver circuit 2, the laser driver circuit 2 controls the tunable laser 3 to linearly sweep the light source according to the laser scanner digital signal, obtains a linear swept frequency light signal, and the tunable laser 3 outputs the linear swept frequency light signal, which is divided into two roads through the first optical fiber coupler 4, one road as reference light enters the HCN gas absorption chamber 8, and the other road as measurement light enters each fiber grating sensor 11 through the optical fiber branching device 9 and the optical fiber ring device 10 in turn;

[0035] S2, the HCN gas absorption chamber 8 absorbs 21 fixed wavelength lights in the reference light and outputs 21 wavelength absorption lines, which are divided into two roads through the second optical fiber coupler 15, one road is converted into 21 pulse signals through one second photoelectric transducer 12, the 21 pulse signals correspond to the 21 wavelength absorption lines one by one, and the 21 pulse signals are evenly divided into L wavelength intervals according to the region between 20 adjacent wavelength absorption lines of the 21 wavelength absorption lines, the first pulse signal of each wavelength interval is used as a trigger signal, and the other road is converted into 21 pulse signals through another second photoelectric transducer 12, the 21 pulse signals are evenly divided into L wavelength intervals according to the region between 20 adjacent wavelength absorption lines of the 21 wavelength absorption lines, and each wavelength interval has M pulse signals, which are used as calibration signals of the tunable laser 3, and the specific process is shown in Figures 2-3 ,Figure 3 The electrical signal for absorbed wavelength light is 1, and the electrical signal for unabsorbed wavelength light is 0. Simultaneously, each fiber Bragg grating sensor 11 reflects the measurement light, which then enters the first photoelectric converter 7 via the fiber optic circulator 10, converting the center wavelength into a measurement electrical signal. It should be noted that the more wavelength ranges there are, the more trigger signals there are, and the more signals are collected simultaneously, resulting in faster speed. However, the fewer calibration signals are available for each wavelength range, leading to decreased accuracy. In this embodiment, L is 5 and M is 4.

[0036] The HCN gas absorption chamber 8 exhibits extremely low wavelength shift in its absorption peak when subjected to external temperature disturbances, with a wavelength drift of less than 0.01 pm / ℃. Other external conditions have no effect on the absorption peak wavelength, and the spacing between each absorption peak is equal. The wavelength absorption line output by the HCN gas absorption chamber 8 is absolutely linear and stable. Furthermore, when there are multiple fiber gratings of different wavelengths in the test link, the wavelength absorption peaks in the five intervals output by the HCN gas absorption chamber 8 can all serve as trigger signals, enabling the data acquisition card 6 to simultaneously trigger signal acquisition from the center wavelength signals of multiple fiber gratings. This increases the acquisition speed of the data acquisition card 6 by five times.

[0037] S3. Since the data acquisition card 6 has a fixed acquisition frequency, when the frequency of the swept light source emitted by the tunable laser 3 is perfectly linear, the time required for the swept light to pass through two adjacent absorption wavelengths is equal. Therefore, the number of sampling points acquired by the data acquisition card 6 at a fixed frequency is the same. When the frequency of the swept light source emitted by the tunable laser 3 is not perfectly linear, the time required for the swept light to pass through two adjacent absorption wavelengths differs. In this case, the number of sampling points acquired by the data acquisition card 6 at a fixed frequency is different. After acquiring the calibration signal, the data acquisition card 6 calculates the value of each wavelength interval through the data processing system of the computer 1. The number of sampling points is used to determine whether the number of sampling points in each wavelength interval is equal. If they are equal, no calibration is performed. If they are not equal, the number of sampling points in the first wavelength interval is used as the linearity calibration benchmark for the swept light. The relationship between the sampling points and the wavelength is fitted using a quadratic curve fitting method to obtain the fitting function between the sampling points and the wavelength. The swept light is then linearly calibrated, and the tunable laser 3 is controlled to output the calibrated swept light signal. This calibration algorithm is simple and highly accurate, which can greatly shorten the calibration time required for the demodulator, reducing the calibration time by half, thereby improving the demodulation speed.

[0038] S4. When the data acquisition card 6 receives the TTL high level converted by the trigger signal, it acquires the measurement electrical signal output by each fiber Bragg grating sensor 11 in the band corresponding to the calibration signal. Based on the calibrated swept-frequency optical signal corresponding to the measurement electrical signal, it demodulates the center wavelength of the measurement light reflected by each fiber Bragg grating sensor 11.

[0039] The wavelength detection precision of the tunable laser fiber grating demodulator with high demodulation speed of the application is 0.01pm, which is 3 times faster than the existing demodulator.

[0040] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any change or replacement within the technical range disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high demodulation speed tunable laser fiber grating demodulator, comprising a data acquisition and processing unit (13), a computer (1), a frequency sweeping laser unit (14), and a first fiber coupler (4), a fiber splitter (9), N fiber loopers (10), N fiber grating sensors (11) and N first photoelectric converters (7) connected in sequence; the frequency sweeping laser unit (14) is used for outputting a frequency sweeping light signal, the output end of which is connected with the fiber splitter (9) through the first fiber coupler (4), the fiber splitter (9) divides the frequency sweeping light signal into N measurement lights, which enter the N fiber grating sensors (11) through the N fiber loopers (10) respectively, the N fiber grating sensors (11) reflect the measurement lights, which enter the N first photoelectric converters (7) through the N fiber loopers (10) respectively, and convert the measurement light signals into measurement electric signals; the output ends of the N first photoelectric converters (7) are connected with the input ends of the data acquisition and processing unit (13) respectively, N=2 n , n=1, 2, 3, 4, 5; characterized in that: Further comprising an HCN gas absorption chamber (8), a second optical fiber coupler (15) and two second photoelectric converters (12); The inlet end of the HCN gas absorption chamber (8) is connected with the output end of the first optical fiber coupler (4), and the outlet end of the HCN gas absorption chamber (8) is connected with the two second photoelectric converters (12) respectively through the second optical fiber coupler (15); The HCN gas absorption chamber (8) is used for absorbing P fixed wavelength lights of the swept frequency light output by the first optical fiber coupler (4) and outputting wavelength absorption lines, wherein the wavelength interval of the P fixed wavelength lights is equidistant; The two second photoelectric converters (12) are both used for converting the wavelength absorption lines output by the HCN gas absorption chamber (8) into P pulse signals, one of which is used as a trigger signal for collecting the center wavelength of the fiber grating by a data acquisition and processing unit (13), and the other of which is used as a calibration signal for a swept laser unit (14); The data acquisition and processing unit (13) receives the trigger signal and collects the measurement electrical signals output by each fiber grating sensor (11); The computer (1) performs linear calibration on the swept frequency light through the calibration signal received by the data acquisition and processing unit (13), and demodulates the center wavelength of the measurement light reflected by each fiber grating sensor (11) according to the calibrated swept frequency light signal corresponding to the measurement electrical signal output by each fiber grating sensor (11) after calibration.

2. The high demodulation speed tunable laser fiber grating demodulator according to claim 1, characterized in that: The data acquisition and processing unit (13) comprises a signal processing circuit (5) and a data acquisition card (6), the input end of the signal processing circuit (5) is connected with the output end of the data acquisition card (6), and the output end of the signal processing circuit (5) is connected with the input end of the computer (1); the output end of the N first photoelectric converters (7) is connected with the input end of the data acquisition card (6) respectively; The swept laser unit (14) comprises a laser driver circuit (2) and a tunable laser (3), the input end of the laser driver circuit (2) is connected with the output end of the computer (1), and the output end of the laser driver circuit (2) is connected with the input end of the tunable laser (3); the tunable laser (3) is used for outputting a swept frequency light signal, and its output end is connected with the fiber splitter (9) through the first optical fiber coupler (4).

3. A method for demodulating a tunable laser fiber grating at high demodulation speed, based on the tunable laser fiber grating demodulator at high demodulation speed according to claim 1 or 2, characterized in that, The method comprises the following steps: S1, the swept laser unit (14) outputs a linear swept frequency light signal, which is divided into two paths through the first optical fiber coupler (4), one of which is used as reference light to enter the HCN gas absorption chamber (8), and the other of which is used as measurement light to enter the fiber grating sensors (11) through the fiber splitter (9) and the fiber loop (10) in sequence; S2, HCN gas absorption chamber (8) absorbs P fixed wavelength light in the reference light, outputs P wavelength absorption lines, is divided into two ways through the second optical fiber coupler (15), one way is converted into P pulse signals through a second photoelectric converter (12), P pulse signals are evenly divided into L wavelength intervals, the first pulse signal of each wavelength interval is taken as a trigger signal, and the other way is converted into P pulse signals through another second photoelectric converter (12), P pulse signals are evenly divided into L wavelength intervals, and each wavelength interval has M pulse signals, and the M pulse signals are taken as calibration signals; at the same time, after the measurement light reflected by each optical fiber grating sensor (11) enters the first photoelectric converter (7) through the optical fiber ring (10), the center wavelength is converted into a measurement electric signal; S3, after the data acquisition and processing unit (13) collects the calibration signal, the sampling point number of each wavelength interval is calculated through the computer (1), and the sampling point number of each wavelength interval is used as a linearity calibration reference of the sweep frequency light, and the sweep frequency light signal after calibration is output by controlling the sweep frequency laser unit (14); S4, when the data acquisition and processing unit (13) receives the TTL high level converted by the trigger signal, the measurement electric signal corresponding to the calibration signal of each optical fiber grating sensor (11) is collected, and the center wavelength of the measurement light reflected by each optical fiber grating sensor (11) is demodulated according to the measurement electric signal corresponding to the sweep frequency light signal after calibration.

4. The high demodulation speed tunable laser fiber grating demodulation method according to claim 3, characterized in that: Step S3 is specifically: after the data acquisition card (6) in the data acquisition and processing unit (13) collects the calibration signal, the sampling point number of each wavelength interval is calculated through the data processing system of the computer (1), and whether the sampling point number of each wavelength interval is equal is judged; if equal, no calibration is performed; if not equal, the sampling point number of the first wavelength interval is used as the linearity calibration reference of the sweep frequency light, the relationship between the sampling points and the wavelengths is fitted in a quadratic sample curve fitting mode, the fitting function between the sampling points and the wavelengths is obtained, the sweep frequency light is linearly calibrated, and the sweep frequency light signal after calibration is output by controlling the tunable laser (3) in the sweep frequency laser unit (14).

5. The high demodulation speed tunable laser fiber grating demodulation method according to claim 4, characterized in that: In step S1, the sweep frequency laser unit (14) outputs a linear sweep frequency light signal, specifically: the computer (1) sends a laser scanning digital signal to the laser driver circuit (2), the laser driver circuit (2) controls the tunable laser (3) to linearly sweep the light source according to the laser scanning digital signal, and a linear sweep frequency light signal is obtained.

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