Triple-frequency laser generating device and method for optical fiber-type rapid sodium temperature and wind measurement lidar

Abstract

The present invention discloses a three-frequency laser generating device and method for a fiber-optic rapid sodium temperature and wind laser radar, belonging to the technical field of multi-frequency laser generating methods. The laser is input through a first fiber coupler, and the horizontally polarized light after passing through the polarization beam splitter cube enters one of the three-frequency optical paths after passing through a quarter-wave plate. After passing through the acousto-optic frequency shifter of the corresponding optical path, it is reflected by the corresponding optical path reflector. The reflected light then passes through the acousto-optic frequency shifter, the quarter-wave plate, and the polarization beam splitter cube of the corresponding optical path in sequence, and then is coupled into the second fiber coupler for output. Among them, by controlling the first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter, and the fourth acousto-optic frequency shifter to shift the frequency or not, the optical path where the laser enters and the frequency of the output laser are controlled. The present invention has the characteristics of high laser frequency purity and high suppression ratio. The three-frequency optical paths can be independently optimized, adjusted, and fixed by three reflectors without crosstalk.

Description

Technical Field

[0001] The present invention belongs to the technical field of multi-frequency laser generation methods, and in particular relates to a three-frequency laser generation device and method for an optical fiber-type rapid sodium temperature and wind measurement laser radar. Background Art

[0002] LiDAR is an advanced active optical remote sensing instrument system with advantages such as high temporal and spatial resolution, high measurement accuracy, and long detection range. Sodium temperature and wind lidar uses sodium atoms in the sodium layer at the top of the mesosphere (approximately 80-105 km) as tracers and utilizes the broadening and Doppler shift of the sodium fluorescence resonance spectrum to detect the temperature and wind fields in the mesosphere, respectively.

[0003] In order to obtain the frequency shift information of the sodium atomic resonance fluorescence backscattering spectrum, the sodium temperature and wind laser radar converts the measurement of the frequency shift information into the detection of the signal intensity of the three frequency positions of the resonance fluorescence spectrum line. To this end, the sodium temperature and wind laser radar needs to simultaneously emit three frequencies of laser into the atmosphere, namely the center frequency of the sodium atomic spectrum line D2a , and two flanking frequencies and . The laser can only output a single frequency The laser with two flanking frequencies cannot be output by the laser itself. Usually, acousto-optic modulation is used to generate the laser with two flanking frequencies. These three laser frequencies need to be emitted alternately and cannot overlap with each other during the emission process to ensure the singleness of the laser frequency.

[0004] Currently, the triple-frequency laser generators used in sodium temperature and wind lidars, both domestically and internationally, mostly use a mechanical shutter to switch frequencies and suppress laser beams that do not experience frequency shifts. With the development of domestic sodium temperature and wind lidar technology, all-solid-state lidar is the trend, characterized by high laser repetition frequency and high average power. Existing mechanical shutters have slow response times, typically in the millisecond range, making them incapable of rapid switching of the triple-frequency laser. Furthermore, the triple-frequency lasers have poor consistency and are susceptible to mechanical switching jitter, making them unsuitable for high-repetition-rate pulsed sodium temperature and wind lidar applications. Summary of the Invention

[0005] In order to solve the problems of slow switching, unsuitability for triple-frequency generation of high repetition rate lasers, poor consistency in triple-frequency laser efficiency, and difficulty in ensuring the consistency of pulse amplification power of pulse dye laser amplifiers in the existing technology, the present invention provides a fiber-optic fast sodium temperature and wind measurement laser radar triple-frequency laser generating device and method. The triple-frequency laser generating device with the same optical path output meets the requirements of the sodium temperature and wind measurement laser radar triple-frequency laser, and has the characteristics of fast switching, easy dimming, and high suppression ratio.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A triple-frequency laser generating device for an optical fiber-type rapid sodium temperature and wind measurement lidar comprises: a first optical fiber coupler, a polarization beam splitter cube, a quarter-wave plate, a first acousto-optic frequency shifter, a second acousto-optic frequency shifter, a first plane reflector, a third acousto-optic frequency shifter, a second plane reflector, a fourth acousto-optic frequency shifter, a third plane reflector, a light baffle, and a second optical fiber coupler;

[0008] The first fiber coupler, the polarization beam splitter cube, the quarter wave plate, the first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter, and the light shield are coaxially installed in sequence;

[0009] The angles between the first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter and the incident laser light are determined according to the Bragg diffraction angle of the crystal inside each acousto-optic frequency shifter;

[0010] The position of the first plane reflector is determined by the separation angle between the 0th order diffracted light and the 1st order diffracted light of the first acousto-optic frequency shifter, and the ...

[0011] The position of the second plane reflector is determined by the separation angle between the 0th order diffracted light and the 1st order diffracted light of the second acousto-optic frequency shifter, and the ...

[0012] The position of the fourth acousto-optic frequency shifter is determined by the separation angle between the 0th-order diffracted light and the 1st-order diffracted light of the third acousto-optic frequency shifter;

[0013] The position of the third plane reflector is confirmed by the separation angle of the 0th order diffraction light and the 1st order diffraction light of the fourth acousto-optic frequency shifter, and makes the laser light path reflected by the third plane reflector coincide with the laser light path incident on the third plane reflector through the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter.

[0014] On the other hand, the present invention also discloses a method for generating triple-frequency lasers for a fiber-optic rapid sodium temperature and wind measurement lidar, the method comprising:

[0015] Inputting laser light through a single-mode optical fiber and collimating the laser light through a first optical fiber coupler to obtain a spatial beam;

[0016] Splitting the spatial light beam through a polarization beam splitter cube to obtain horizontally polarized light;

[0017] Passing the horizontally polarized light through a quarter-wave plate to obtain circularly polarized light;

[0018] The circularly polarized light is frequency-shifted by a first acousto-optic frequency shifter, reflected by a first plane reflector, sequentially passed through the first acousto-optic frequency shifter, a quarter-wave plate, and a polarization beam splitter cube, and coupled into an optical fiber through a second fiber coupler, and one of the frequency-shifted lights is output;

[0019] The circularly polarized light passes through a first acousto-optic frequency shifter without frequency shifting, then passes through a second acousto-optic frequency shifter to generate frequency shifting, and is reflected by a second plane reflector, and then passes through the second acousto-optic frequency shifter, the first acousto-optic frequency shifter, a quarter-wave plate, and a polarization beam splitter cube in sequence, and is coupled into an optical fiber through a second fiber coupler to output another frequency-shifted light;

[0020] The circularly polarized light sequentially passes through a first acousto-optic frequency shifter and a second acousto-optic frequency shifter without frequency shifting, then passes through a third acousto-optic frequency shifter to generate frequency shifting, then passes through a fourth acousto-optic frequency shifter to generate frequency shifting that is equal in magnitude and opposite in direction to that of the third acousto-optic frequency shifter, and is reflected by a third plane reflector. The light then sequentially passes through the fourth acousto-optic frequency shifter, the third acousto-optic frequency shifter, the second acousto-optic frequency shifter, the first acousto-optic frequency shifter, a quarter-wave plate, and a polarization beam splitter cube, and is coupled into an optical fiber through a second optical fiber coupler to output fundamental frequency light.

[0021] The beneficial effects of the present invention are:

[0022] (1) The optical fiber type rapid sodium temperature and wind measurement laser radar three-frequency laser generating device of the present invention adopts a full acousto-optic frequency shifting method to realize the generation of three frequencies. It can realize the rapid switching of the three-frequency optical path through multiple TTL level signals. The optical path switching only takes tens of nanoseconds and can generate a high repetition rate three-frequency laser.

[0023] (2) The optical fiber-type rapid sodium temperature and wind laser radar triple-frequency laser generating device of the present invention is incident through the same optical path. The triple-frequency optical paths can be independently optimized, adjusted and fixed within the system through three reflectors, which facilitates the adjustment of the overlap of the triple-frequency output optical paths, so that the triple-frequency output optical paths can be output in a high-efficiency optical fiber coupling manner on the same optical path, which is convenient for matching with the pulse dye laser amplifier.

[0024] (3) The three-frequency optical paths of the optical fiber-type rapid sodium temperature and wind measurement laser radar three-frequency laser generating device of the present invention are separated from the incident optical path by Bragg diffraction of the acousto-optic frequency shifter. The three-frequency lasers are completely separated by time and space combined control without crosstalk. The output three-frequency lasers have the characteristics of high laser frequency purity and high suppression ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 (a) shows the triple-frequency laser generator of the optical fiber type rapid sodium temperature and wind laser radar of the present invention. Schematic diagram of the laser light path;

[0026] Figure 1 (b) shows the triple-frequency laser generator of the optical fiber type rapid sodium temperature and wind laser radar of the present invention. Schematic diagram of the laser light path;

[0027] Figure 1 (c) shows the triple-frequency laser generator of the optical fiber type rapid sodium temperature and wind laser radar of the present invention. Schematic diagram of the laser light path;

[0028] Figure 2 This is the timing diagram of the TTL trigger signal of the power driver input to the acousto-optic frequency shifter.

[0029] Reference numerals:

[0030] 1. First fiber coupler; 2. Polarization beam splitter cube; 3. Quarter wave plate; 4. First acousto-optic frequency shifter; 5. Second acousto-optic frequency shifter; 6. First plane mirror; 7. Third acousto-optic frequency shifter; 8. Second plane mirror; 9. Fourth acousto-optic frequency shifter; 10. Third plane mirror; 11. Light baffle; 12. Second fiber coupler. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0032] Figures 1(a)-1(c) illustrate a schematic diagram of the triple-frequency laser generator for the fiber-based rapid sodium temperature and wind measurement lidar of the present invention. The triple-frequency laser generator comprises a first fiber coupler 1, a polarization beam splitter cube 2, a quarter-wave plate 3, a first acousto-optic frequency shifter 4, a second acousto-optic frequency shifter 5, a first plane reflector 6, a third acousto-optic frequency shifter 7, a second plane reflector 8, a fourth acousto-optic frequency shifter 9, a third plane reflector 10, a light baffle 11, and a second fiber coupler 12. The polarization beam splitter cube 2 is adjusted and positioned perpendicular to the incident light axis and then cured. The first, second, third, and fourth acousto-optic frequency shifters 4, 5, 7, and 9 are all positioned perpendicular to the incident light axis at their respective operating diffraction angles, adjusted to maximize efficiency, and then cured.

[0033] The first acousto-optic frequency shifter 4, the second acousto-optic frequency shifter 5, the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 control their working states according to the radio frequency pulse signal output by the power driver, and the power driver modulates the output radio frequency pulse signal according to the TTL pulse signal input thereto.

[0034] The triple-frequency laser generating device controls the working state of each acousto-optic frequency shifter by inputting a TTL level signal of a power driver, thereby controlling the change of the laser frequency and obtaining lasers of three frequencies. When the TTL pulse signal input of the power driver of the first acousto-optic frequency shifter 4 is at a high level, the TTL pulse signal input of the power driver of the second acousto-optic frequency shifter 5, the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 is at a low level, the output frequency can be When the TTL pulse signal input of the power driver of the second acousto-optic frequency shifter 5 is high, the TTL pulse signal input of the power driver of the first acousto-optic frequency shifter 4, the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 is low, the output frequency is When the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 power driver TTL input is high, the first acousto-optic frequency shifter 4 and the second acousto-optic frequency shifter 5 TTL pulse signal input is low, the output frequency is The laser, represents the fundamental frequency component, Represents the frequency shift component.

[0035] Specifically, the laser light collimated and output by the first fiber coupler 1 is split by the polarization beam splitter cube 2, wherein the S light (perpendicular to the incident plane) is reflected (the reflected light is not shown in the figure), and most of the P light (parallel to the incident plane) is transmitted, so that all the transmitted light is P light, and the S component light perpendicular to the incident plane returned by the later-described device is reflected out; the transmitted horizontally polarized light parallel to the incident plane is converted into circularly polarized light after passing through the quarter-wave plate 3, and the circularly polarized light returned after passing through the later-described device is converted into vertically polarized light perpendicular to the incident plane after passing through the quarter-wave plate 3 again. When the vertically polarized light reaches the polarization beam splitter cube 2, since the light is now polarized perpendicular to the incident plane, it will be reflected out at the splitting surface of the polarization beam splitter cube 2.

[0036] As shown in Figure 1 (a), the light after passing through the quarter-wave plate 3 is divided into three paths to generate three-frequency lasers, wherein the first acousto-optic frequency shifter 4 and the first plane reflector 6 constitute The incident circularly polarized light after passing through the quarter-wave plate 3 is diffracted by the first acousto-optic frequency shifter 4, reflected by the first plane reflector 6, and then sequentially passes through the first acousto-optic frequency shifter 4, the quarter-wave plate 3, and the polarization beam splitter cube 2, and is coupled by the second fiber coupler 12 before being output. The unshifted light after passing through the first acousto-optic frequency shifter 4 passes through the second acousto-optic frequency shifter 5 and the third acousto-optic frequency shifter 7 in sequence and is absorbed by the light baffle 11. The second acousto-optic frequency shifter 5 and the third acousto-optic frequency shifter 7 do not work, and the light after passing through the second acousto-optic frequency shifter 5 and the third acousto-optic frequency shifter 7 does not diffract;

[0037] As shown in FIG1( b ), the first acousto-optic frequency shifter 4, the second acousto-optic frequency shifter 5 and the second plane reflector 8 constitute A laser generating optical path, wherein the first acousto-optic frequency shifter 4 is not working, the incident circularly polarized light after passing through the quarter-wave plate 3 does not diffract after passing through the first acousto-optic frequency shifter 4, the circularly polarized light after passing through the first acousto-optic frequency shifter 4 is diffracted when reaching the second acousto-optic frequency shifter 5, and then reflected by the second plane reflector 8, and then sequentially passes through the second acousto-optic frequency shifter 5, the first acousto-optic frequency shifter 4, the quarter-wave plate 3, and the polarization beam splitter cube 2, and is coupled through the second fiber coupler 12 before being output, the unshifted light after passing through the second acousto-optic frequency shifter 5 passes through the third acousto-optic frequency shifter 7 and is absorbed by the light baffle 11, the third acousto-optic frequency shifter 7 is not working, and the light passing through the third acousto-optic frequency shifter 7 does not diffract;

[0038] As shown in FIG1(c), the first acousto-optic frequency shifter 4, the second acousto-optic frequency shifter 5, the third acousto-optic frequency shifter 7, the fourth acousto-optic frequency shifter 9 and the third plane reflector 10 constitute The laser generates an optical path, wherein the first acousto-optic frequency shifter 4 and the second acousto-optic frequency shifter 5 are not working, the incident circularly polarized light after passing through the quarter-wave plate 3 does not diffract after passing through the first acousto-optic frequency shifter 4 and the second acousto-optic frequency shifter 5, and the circularly polarized light after passing through the second acousto-optic frequency shifter 5 diffracts after passing through the third acousto-optic frequency shifter 7, generating The laser light diffracted by the third acousto-optic frequency shifter 7 is generated by the fourth acousto-optic frequency shifter 9. The frequency shift, the output frequency is The laser light passes through the fourth acousto-optic frequency shifter 9 and generates a frequency of The laser is reflected by the third plane reflector 10, and then passes through the fourth acousto-optic frequency shifter 9, the third acousto-optic frequency shifter 7, the second acousto-optic frequency shifter 5, the first acousto-optic frequency shifter 4, the quarter-wave plate 3, the polarization beam splitter cube 2, and is coupled through the second fiber coupler 12 before being output. The unshifted light passing through the third acousto-optic frequency shifter 7 is absorbed by the light baffle 11.

[0039] Among them, the first acousto-optic frequency shifter 4, the second acousto-optic frequency shifter 5, the third acousto-optic frequency shifter 7, and the fourth acousto-optic frequency shifter 9 are finely adjusted to ensure diffraction efficiency and are fixed after being adjusted to the optimal value. The first plane reflector 6, the second plane reflector 8, and the third plane reflector 10 are finely adjusted to ensure the working efficiency of the return light and are fixed after being adjusted to the optimal value. The first fiber coupler 1, the polarization beam splitter cube 2, the quarter-wave plate 3, the first acousto-optic frequency shifter 4, the second acousto-optic frequency shifter 5, the third acousto-optic frequency shifter 7, and the light shielding plate 11 are coaxially installed. The angle between the first acousto-optic frequency shifter 4, the second acousto-optic frequency shifter 5, the third acousto-optic frequency shifter 7 and the incident light is determined according to the Bragg diffraction angle of the crystal inside each acousto-optic frequency shifter. The position of the first plane reflector 6 is confirmed by the separation angle of the 0th order diffracted light and the 1st order diffracted light of the first acousto-optic frequency shifter 4, and the first plane reflector 6 is fixed. The reflected laser is coincident with the incident light path; the position of the second plane reflector 8 is confirmed by the separation angle of the 0th order diffraction light and the 1st order diffraction light of the second acousto-optic frequency shifter 5, and the reflected laser is coincident with the incident light path; the fourth acousto-optic frequency shifter 9 is confirmed by the separation angle of the 0th order diffraction light and the 1st order diffraction light of the third acousto-optic frequency shifter 7, and the position of the third plane reflector 10 is confirmed by the separation angle of the 0th order diffraction light and the 1st order diffraction light of the fourth acousto-optic frequency shifter 9, and the reflected laser is coincident with the incident light path.

[0040] According to an embodiment of the present invention, Figure 2 This is a timing control diagram of the TTL trigger signal input to the power driver of the acousto-optic frequency shifter according to an embodiment of the present invention, wherein S1 is the TTL trigger signal input to the power driver of the third acousto-optic frequency shifter 7, S2 is the TTL trigger signal input to the power driver of the fourth acousto-optic frequency shifter 9, S3 is the TTL trigger signal input to the power driver of the first acousto-optic frequency shifter 4, S4 is the TTL trigger signal input to the power driver of the second acousto-optic frequency shifter 5, and T is a pulse period. During the first third of a pulse period, the TTL level applied to the power drivers of the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 is a high level, and the TTL level applied to the power drivers of the first acousto-optic frequency shifter 4 and the second acousto-optic frequency shifter 5 is a low level. The third acousto-optic frequency shifter 7 shifts the laser frequency upward. (100 MHZ is recommended), the fourth acousto-optic frequency shifter 9 shifts the laser frequency downward , the laser frequency output by the acousto-optic modulation system is , the 0th order diffracted light of the third acousto-optic frequency shifter 7 is absorbed by the light shield 11; in the middle third of a pulse period, the TTL level of the power driver applied to the first acousto-optic frequency shifter 4 is high, and the TTL level of the power driver applied to the second acousto-optic frequency shifter 5, the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 is low, and the first acousto-optic frequency shifter 4 shifts the laser frequency upward After the laser passes through the first acousto-optic frequency shifter 4 twice, the laser frequency shifts upward. The 0th order diffracted light of the first acousto-optic frequency shifter 4 passes through the second acousto-optic frequency shifter 5 and the third acousto-optic frequency shifter 7 and is absorbed by the light shielding plate 11. The laser frequency output by the acousto-optic modulation system is In the last third of a pulse cycle, the TTL level of the power driver applied to the second acousto-optic frequency shifter 5 is high, and the TTL level of the power driver applied to the first acousto-optic frequency shifter 4, the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 is low. The first acousto-optic frequency shifter 4 does not modulate the laser frequency, and the second acousto-optic frequency shifter 5 shifts the laser frequency downward. After the laser passes through the second acousto-optic frequency shifter 5 twice, the laser frequency shifts downward. The 0th order diffracted light of the second acousto-optic frequency shifter 5 passes through the third acousto-optic frequency shifter 7 and is absorbed by the light shielding plate 11. The laser frequency output by the acousto-optic modulation system is According to the embodiment of the present invention, the TTL trigger signal of the power driver is input, and the entire acousto-optic modulation system finally outputs the 、 、 Alternating triple-frequency continuous laser.

[0041] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A three-frequency laser generating device for a fiber-optic rapid sodium temperature and wind laser radar, characterized in that: include: A first fiber coupler, a polarization beam splitter cube, a quarter wave plate, a first acousto-optic frequency shifter, a second acousto-optic frequency shifter, a first plane reflector, a third acousto-optic frequency shifter, a second plane reflector, a fourth acousto-optic frequency shifter, a third plane reflector, a light baffle, and a second fiber coupler; The first fiber coupler, the polarization beam splitter cube, the quarter wave plate, the first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter, and the light shield are coaxially installed in sequence; The angles between the first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter and the incident laser light are determined according to the Bragg diffraction angle of the crystal inside each acousto-optic frequency shifter; The position of the first plane reflector is determined by the separation angle between the 0th order diffracted light and the 1st order diffracted light of the first acousto-optic frequency shifter, and the ... The position of the second plane reflector is determined by the separation angle between the 0th order diffracted light and the 1st order diffracted light of the second acousto-optic frequency shifter, and the ... The position of the fourth acousto-optic frequency shifter is determined by the separation angle between the 0th-order diffracted light and the 1st-order diffracted light of the third acousto-optic frequency shifter; The position of the third plane reflector is confirmed by the separation angle of the 0th order diffraction light and the 1st order diffraction light of the fourth acousto-optic frequency shifter, and makes the laser light path reflected by the third plane reflector coincide with the laser light path incident on the third plane reflector through the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter.

2. The optical fiber type rapid sodium temperature and wind measurement laser radar triple-frequency laser generating device according to claim 1, characterized in that: The polarization beam splitter cube is adjusted and placed perpendicular to the incident light axis and solidified; the first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter are all placed perpendicular to the incident light axis at their respective working diffraction angles and solidified.

3. The optical fiber type rapid sodium temperature and wind measurement laser radar triple-frequency laser generating device according to claim 1, characterized in that: The first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter control their working states according to the radio frequency pulse signal output by the power driver.

4. The optical fiber type rapid sodium temperature and wind measurement laser radar triple-frequency laser generating device according to claim 3, characterized in that: The radio frequency pulse signal includes a TTL pulse signal.

5. The optical fiber type rapid sodium temperature and wind measurement laser radar triple-frequency laser generating device according to claim 1, characterized in that: When the TTL pulse signal input of the power driver of the first acousto-optic frequency shifter is high level, the TTL pulse signal input of the power driver of the second acousto-optic frequency shifter, the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter is low level, the output frequency is When the TTL pulse signal input of the power driver of the second acousto-optic frequency shifter is high, the TTL pulse signal input of the power driver of the first acousto-optic frequency shifter, the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter is low, the output frequency is When the TTL pulse signal input of the power driver of the third and fourth acousto-optic frequency shifters is high, and the TTL pulse signal input of the first and second acousto-optic frequency shifters is low, the output frequency is The laser, represents the fundamental frequency component, Represents the frequency shift component.

6. A method for generating triple-frequency lasers for a fiber-optic rapid sodium temperature and wind laser radar, applied to a triple-frequency laser generating device for a fiber-optic rapid sodium temperature and wind laser radar according to any one of claims 1 to 5, characterized in that: The method comprises: Inputting laser light through a single-mode optical fiber and collimating the laser light through a first optical fiber coupler to obtain a spatial beam; Splitting the spatial light beam through a polarization beam splitter cube to obtain horizontally polarized light; Passing the horizontally polarized light through a quarter-wave plate to obtain circularly polarized light; The circularly polarized light is frequency-shifted by a first acousto-optic frequency shifter, reflected by a first plane reflector, sequentially passed through the first acousto-optic frequency shifter, a quarter-wave plate, and a polarization beam splitter cube, and coupled into an optical fiber through a second fiber coupler, and one of the frequency-shifted lights is output; The circularly polarized light passes through a first acousto-optic frequency shifter without frequency shifting, then passes through a second acousto-optic frequency shifter to generate frequency shifting, and is reflected by a second plane reflector, and then passes through the second acousto-optic frequency shifter, the first acousto-optic frequency shifter, a quarter-wave plate, and a polarization beam splitter cube in sequence, and is coupled into an optical fiber through a second fiber coupler to output another frequency-shifted light; The circularly polarized light sequentially passes through a first acousto-optic frequency shifter and a second acousto-optic frequency shifter without frequency shifting, then passes through a third acousto-optic frequency shifter to generate frequency shifting, then passes through a fourth acousto-optic frequency shifter to generate frequency shifting that is equal in magnitude and opposite in direction to that of the third acousto-optic frequency shifter, and is reflected by a third plane reflector. The light then sequentially passes through the fourth acousto-optic frequency shifter, the third acousto-optic frequency shifter, the second acousto-optic frequency shifter, the first acousto-optic frequency shifter, a quarter-wave plate, and a polarization beam splitter cube, and is coupled into an optical fiber through a second optical fiber coupler to output fundamental frequency light.

7. The method for generating triple-frequency lasers for a fiber-optic rapid sodium temperature and wind laser radar according to claim 6, characterized in that: The first acousto-optic frequency shifter, the second acousto-optic frequency shifter, the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter are controlled to work or not work by the input TTL pulse signal.

8. The method for generating triple-frequency lasers for a fiber-optic rapid sodium temperature and wind laser radar according to claim 6, characterized in that: By inputting a periodic TTL pulse signal, a periodic triple-frequency laser is generated.

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