Optical fiber type rapid sodium temperature and wind measurement laser radar three-frequency laser generation device and method

Abstract

The invention discloses an optical fiber type rapid sodium temperature and wind measurement laser radar three-frequency laser generation device and method, and belongs to the technical field of multi-frequency laser generation methods. Laser is input through the first optical fiber coupler, and horizontal polarized light passing through the polarization beam splitting cube enters one of the three-frequency light paths after passing through the quarter-wave plate and is reflected by the corresponding light path reflector after passing through the acousto-optic frequency shifter of the corresponding light path. And the reflected light sequentially passes through the acousto-optic frequency shifter, the quarter-wave plate and the polarization beam splitting cube of the corresponding light path, and then is coupled to enter the second optical fiber coupler to be output. Wherein 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 shift frequency or not to shift frequency, so that the light path into which the laser enters and the frequency of the output laser are controlled. The device has the characteristics of high laser frequency purity and high suppression ratio, the three-frequency optical path can be independently optimized, adjusted and fixed through the three reflectors, and there is no crosstalk between the three reflectors.

Description

Technical Field

[0001] The invention belongs to the technical field of multi-frequency laser generation methods, and specifically 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 the advantages of high temporal and spatial resolution, high measurement accuracy, and long detection distance. Sodium temperature and wind lidar uses sodium atoms in the sodium layer at the top of the mesosphere (about 80~105km) as tracers, and uses the spectrum broadening and Doppler shift of the sodium fluorescence resonance spectrum to detect the temperature and wind field in the mesosphere.

[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 at 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, the laser with two flanking frequencies is generated by acousto-optic modulation. 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] At present, the three-frequency laser generating devices of sodium temperature and wind laser radars at home and abroad mostly use mechanical shutters to achieve frequency switching and suppress laser beams that do not produce frequency shifts. With the development of domestic sodium temperature and wind laser radar technology, all-solid-state laser radar is the development trend. All-solid-state laser radar has the characteristics of high laser repetition frequency and high average power. The original mechanical shutter has a slow response time, usually in the millisecond level, and cannot achieve rapid switching of the three-frequency laser. In addition, the consistency of the three-frequency laser is poor and is easily affected by mechanical switching jitter. It cannot be used in high repetition frequency pulse sodium temperature and wind laser radar applications. Summary of the invention

[0005] In order to solve the problems in the prior art that the triple-frequency generating device has slow switching, is not suitable for the triple-frequency generation of high repetition frequency laser, has poor consistency in triple-frequency laser efficiency, and is difficult to ensure the consistency of pulse amplification power of pulse dye laser amplifier, the present invention provides a fiber-optic fast sodium temperature and wind measurement laser radar triple-frequency laser generating device and method, a triple-frequency laser generating device with the same optical path output, which meets the requirements of the sodium temperature and wind measurement laser radar triple-frequency laser, and has the characteristics of fast switching, easy dimming, high suppression ratio, etc.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A three-frequency laser generating device for an optical fiber fast sodium temperature and wind laser radar, comprising: 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; Wherein, the first optical 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 shielding plate 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 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 of the 0th order diffracted light and the 1st order diffracted light of the first acousto-optic frequency shifter, and the laser light path reflected by the first plane reflector coincides with the laser light path incident on the first plane reflector via the first acousto-optic frequency shifter; The position of the second plane reflector is determined by the separation angle of the 0th order diffracted light and the 1st order diffracted light of the second acousto-optic frequency shifter, and the laser light path reflected by the second plane reflector coincides with the laser light path incident on the second plane reflector via the second acousto-optic frequency shifter; The position of the fourth acousto-optic frequency shifter is confirmed by the separation angle of 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 to the third plane reflector via the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter.

[0007] On the other hand, the present invention also discloses a method for generating triple-frequency lasers of an optical fiber-type rapid sodium temperature and wind measurement laser radar, the method comprising: 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 by 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 the first acousto-optic frequency shifter, and after being reflected by the first plane reflector, it passes through the first acousto-optic frequency shifter, the quarter-wave plate, the polarization beam splitter cube in sequence, and is coupled into the optical fiber through the second optical fiber coupler, and one of the frequency-shifted lights is output; The circularly polarized light passes through the first acousto-optic frequency shifter but does not generate frequency shift, then passes through the second acousto-optic frequency shifter to generate frequency shift, and is reflected by the second plane reflector, then passes through the second acousto-optic frequency shifter, the first acousto-optic frequency shifter, the quarter wave plate, the polarization beam splitter cube in sequence, and is coupled into the optical fiber through the second optical fiber coupler to output another frequency-shifted light; The circularly polarized light passes through the first acousto-optic frequency shifter and the second acousto-optic frequency shifter in sequence without generating frequency shift, passes through the third acousto-optic frequency shifter to generate frequency shift, passes through the fourth acousto-optic frequency shifter to generate frequency shift that is equal in magnitude and opposite in direction to that of the third acousto-optic frequency shifter, and is reflected by the third plane reflector, and then 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 in sequence, and is coupled into an optical fiber through a second optical fiber coupler to output fundamental frequency light.

[0008] The beneficial effects of the present invention are: (1) The optical fiber type rapid sodium temperature and wind laser radar three-frequency laser generating device of the present invention adopts a full acoustic and optical frequency shifting method to realize the generation of three frequencies. The three-frequency optical path can be quickly switched through multiple TTL level signals. The optical path switching only takes tens of nanoseconds, and a high repetition rate three-frequency laser can be generated.

[0009] (2) The three-frequency laser generating device of the optical fiber-type rapid sodium temperature and wind laser radar of the present invention is incident through the same optical path. The three-frequency optical path can be independently optimized and adjusted and fixed inside the system through three reflectors, which facilitates the adjustment of the overlap of the three-frequency output optical paths, so that the same optical path can be output in a high-efficiency optical fiber coupling manner, which is convenient for matching with a pulse dye laser amplifier.

[0010] (3) The three-frequency optical paths of the three-frequency laser generating device of the optical fiber-type rapid sodium temperature and wind laser radar 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

[0011] FIG1 (a) shows a three-frequency laser generating device of the optical fiber type rapid sodium temperature and wind laser radar of the present invention. The frequency of the laser generating device is Schematic diagram of laser light path; FIG1 (b) shows a three-frequency laser generating device of the optical fiber type rapid sodium temperature and wind laser radar of the present invention. The frequency of the laser generating device is Schematic diagram of laser light path; FIG1 (c) shows a three-frequency laser generating device of the optical fiber type rapid sodium temperature and wind laser radar of the present invention. The frequency of the laser generating device is Schematic diagram of laser light path; Figure 2This is the timing diagram of the TTL trigger signal of the power driver of the input acousto-optic frequency shifter.

[0012] Reference numerals: 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 reflector; 7. Third acousto-optic frequency shifter; 8. Second plane reflector; 9. Fourth acousto-optic frequency shifter; 10. Third plane reflector; 11. Light baffle; 12. Second fiber coupler. DETAILED DESCRIPTION

[0013] 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.

[0014] As shown in Figure 1 (a) to Figure 1 (c), it is a schematic diagram of the three-frequency laser generating device of the optical fiber fast sodium temperature and wind laser radar of the present invention, and the three-frequency laser generating device includes: a first optical 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 optical fiber coupler 12. The polarization beam splitter cube 2 is adjusted to be placed perpendicular to the incident light axis and cured. 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 all placed perpendicular to the incident light axis at their respective working diffraction angles, and the efficiency is adjusted to the highest before curing.

[0015] 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 RF pulse signal output by the power driver, and the power driver modulates the output RF pulse signal according to its input TTL pulse signal.

[0016] The three-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 with 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, and 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 TTL input of the power driver of the third acousto-optic frequency shifter 7 and the fourth acousto-optic frequency shifter 9 is high, the TTL pulse signal input of the first acousto-optic frequency shifter 4 and the second acousto-optic frequency shifter 5 is low, the output frequency is The laser, represents the fundamental frequency component, Represents the frequency shift component.

[0017] Specifically, the laser output by the first optical fiber coupler 1 is collimated and split by the polarization beam splitter 2, wherein the S light (perpendicular to the incident plane) will be 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 horizontal polarized light parallel to the incident plane is converted into circular polarized light after passing through the quarter-wave plate 3, and the circular polarized light returned after passing through the later-described device is converted into vertical polarized light perpendicular to the incident plane after passing through the quarter-wave plate 3 again. When the vertical polarized light reaches the polarization beam splitter 2, since the light is polarized light perpendicular to the incident plane at this time, it will be reflected out at the splitting surface of the polarization beam splitter 2.

[0018] As shown in FIG1( 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 then coupled by the second optical fiber coupler 12 and output, the non-shifted light after passing through the first acousto-optic frequency shifter 4 sequentially passes through the second acousto-optic frequency shifter 5 and the third acousto-optic frequency shifter 7 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; 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 does not work, 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 diffracts when reaching the second acousto-optic frequency shifter 5, and then is 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 then is coupled through the second optical fiber coupler 12 and then output, the non-shifted 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 does not work, and the light after passing through the third acousto-optic frequency shifter 7 does not diffract; 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 do not work, 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 beam passes through the third acousto-optic frequency shifter 7 and the diffracted light passes through the fourth acousto-optic frequency shifter 9 to generate The frequency shift 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, and the polarization beam splitter cube 2 in sequence, and is coupled through the second fiber coupler 12 and then output, wherein the unshifted light passing through the third acousto-optic frequency shifter 7 is absorbed by the light blocking plate 11.

[0019] 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 ensure the diffraction efficiency through fine adjustment, and are fixed after being adjusted to the best. The first plane reflector 6, the second plane reflector 8, and the third plane reflector 10 ensure the working efficiency of the return light through fine adjustment, and are fixed after being adjusted to the best. 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 shading plate 11 are coaxially installed. The angle between the first acousto-optic frequency shifter 4, the second acousto-optic frequency shifter 5, and 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 according to the Bragg diffraction angle of the crystal inside each acousto-optic frequency shifter. The reflected laser is coincident with the incident optical 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 optical 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 optical path.

[0020] According to an embodiment of the present invention, Figure 2It is a timing control diagram of the TTL trigger signal input to the power driver of the acousto-optic frequency shifter according to the 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 cycle. In the first third of a pulse cycle, 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, and the third acousto-optic frequency shifter 7 shifts the laser frequency upward. (100 MHZ is acceptable), 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 shading plate 11; in the middle one-third of a pulse cycle, the TTL level of the power driver applied to the first acousto-optic frequency shifter 4 is a high level, 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 a low level, 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 shading 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 shading 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 , , Alternating triple frequency continuous laser.

[0021] 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 description is only a specific embodiment of the present invention and is 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 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; Wherein, the first optical 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 shielding plate 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 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 of the 0th order diffracted light and the 1st order diffracted light of the first acousto-optic frequency shifter, and the laser light path reflected by the first plane reflector coincides with the laser light path incident on the first plane reflector via the first acousto-optic frequency shifter; The position of the second plane reflector is determined by the separation angle of the 0th order diffracted light and the 1st order diffracted light of the second acousto-optic frequency shifter, and the laser light path reflected by the second plane reflector coincides with the laser light path incident on the second plane reflector via the second acousto-optic frequency shifter; The position of the fourth acousto-optic frequency shifter is confirmed by the separation angle of 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 to the third plane reflector via the third acousto-optic frequency shifter and the fourth acousto-optic frequency shifter.

2. The optical fiber type rapid sodium temperature and wind laser radar triple-frequency laser generating device according to claim 1 is characterized in that: The polarization beam splitter cube is adjusted to be 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 is 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 laser radar triple-frequency laser generating device according to claim 3 is characterized in that: The radio frequency pulse signal includes a TTL pulse signal.

5. The optical fiber type rapid sodium temperature and wind 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, and the TTL pulse signal input of the power driver of the second, third and fourth acousto-optic frequency shifters 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, 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 by 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 the first acousto-optic frequency shifter, and after being reflected by the first plane reflector, it passes through the first acousto-optic frequency shifter, the quarter-wave plate, the polarization beam splitter cube in sequence, and is coupled into the optical fiber through the second optical fiber coupler, and one of the frequency-shifted lights is output; The circularly polarized light passes through the first acousto-optic frequency shifter but does not generate frequency shift, then passes through the second acousto-optic frequency shifter to generate frequency shift, and is reflected by the second plane reflector, then passes through the second acousto-optic frequency shifter, the first acousto-optic frequency shifter, the quarter wave plate, the polarization beam splitter cube in sequence, and is coupled into the optical fiber through the second optical fiber coupler to output another frequency-shifted light; The circularly polarized light passes through the first acousto-optic frequency shifter and the second acousto-optic frequency shifter in sequence without generating frequency shift, passes through the third acousto-optic frequency shifter to generate frequency shift, passes through the fourth acousto-optic frequency shifter to generate frequency shift that is equal in magnitude and opposite in direction to that of the third acousto-optic frequency shifter, and is reflected by the third plane reflector, and then 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 in sequence, and is coupled into an optical fiber through a second optical fiber coupler to output fundamental frequency light.

7. A 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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