High-precision frequency modulation module based on single acousto-optic modulator, and high-performance dual-frequency laser generation method and device

Abstract

The invention belongs to the field of dual-frequency laser and precision measurement, and particularly relates to a high-precision frequency modulation module based on a single acousto-optic modulator and a high-performance dual-frequency laser generation method and device. The problems that an existing double-frequency laser generation scheme is poor in stability and large in system integration size are solved. The device comprises a single-frequency laser light source, a mode matcher, a high-precision frequency modulation module and a polarization control assembly, wherein the high-precision frequency modulation module comprises a single acousto-optic modulator based on the Raman-Niss principle, a power amplifier and a radio frequency output signal source; the single-frequency laser light source is used for generating fundamental frequency light, the fundamental frequency light passes through the isolator, then passes through the mode matcher to be subjected to mode matching, then is subjected to high-precision frequency modulation of the acousto-optic modulator based on the Raman-Niss principle, and finally outputs a beam of orthogonal line polarization double-frequency laser with high power and high frequency stability; miniaturized integration of the system is realized by adopting a single acousto-optic modulator, and the system can be used for measuring and manufacturing ultra-precise measuring instruments.

Description

Technical Field

[0001] The present invention provides a high-precision frequency modulation module based on a single acousto-optic modulator, a high-performance dual-frequency laser generation method and device, belonging to the fields of dual-frequency laser technology and precision measurement technology. Background Art

[0002] With its excellent anti-interference ability and extraordinary frequency stability, dual-frequency laser technology has demonstrated extraordinary application value in multiple cutting-edge technology fields such as high-precision positioning, precise mapping, ultra-precision measurement, and directional measurement, and has given rise to a number of technological innovations and application achievements. In the in-depth exploration of scientific research, dual-frequency lasers, with their high resolution and high-precision measurement capabilities, have become an indispensable important tool for conducting precision experiments. With the rapid progress of photon technology, especially the booming rise of emerging technology fields such as quantum information processing and super-resolution imaging, the demand for dual-frequency laser technology has been continuously climbing, further promoting the continuous breakthroughs in the accuracy and stability of this technology. It is worth noting that the performance of the dual-frequency laser light source directly determines the accuracy of the measurement results. Therefore, ultra-high-performance dual-frequency laser light sources have always been a hot research field, attracting numerous researchers to continuously engage in the exploration and innovation of this cutting-edge technology.

[0003] Existing dual-frequency laser generation methods mainly include: Zeeman energy level splitting, acousto-optic modulation frequency shift, birefringence-Zeeman method, and dual longitudinal mode frequency offset locking, etc. Among them, the Zeeman energy level splitting method is the most widely used method for generating dual-frequency lasers in currently commercially available mature products. However, whether the magnetic field is applied longitudinally or transversely, it will be limited by the environment and the helium-neon laser's own gas chamber's inability to support high power, resulting in insufficient output power of the dual-frequency laser. At the same time, affected by frequency difference locking, problems such as a decrease in output power with the increase in frequency difference will occur. The scheme for generating dual-frequency lasers using the birefringence-Zeeman effect was proposed by the research group of Tsinghua University. This method solves the influence of frequency difference locking. The optical power is only about 1 mW in the range of 0 - 40 MHz. Although it avoids the problem that it is impossible to achieve a large frequency difference output when generating dual-frequency lasers using the Zeeman effect, it still faces problems such as low optical power and frequency stability. In addition, the lasers produced by this method can only output dual-frequency lasers with specific frequency differences and need to be customized. The frequency difference of the dual-frequency laser prepared by the dual longitudinal mode frequency offset locking method reaches 600 - 1000 MHz. Such a high frequency cannot be directly applied to the fields of pointing measurement and ultra-precision measurement, which will lead to an increase in measurement error. The traditional acousto-optic modulation method for frequency modulation is around 80 MHz. Existing methods usually use two acousto-optic modulators for different frequency modulations and then perform difference frequency. Due to the use of multiple acousto-optic modulators, the supporting devices used in the system are more and more complex, which leads to more noise sources for difference frequency, poor coordination, and also requires more complex mode matching. Moreover, acousto-optic modulation also has relatively high requirements for the modulation frequency, which is not conducive to the miniaturization design of the system. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes a high-precision frequency modulation module based on a single acousto-optic modulator, a high-performance dual-frequency laser generation method and device.

[0005] The technical solution adopted by the present invention is as follows: A high-precision frequency modulation module based on a single acousto-optic modulator includes a single acousto-optic modulator based on the Raman-Nath principle, a power amplifier, and a radio frequency output signal source. The output end of the radio frequency output signal source is connected to the input end of the power amplifier, and the output end of the power amplifier is connected to the input end of the acousto-optic modulator. High-precision frequency modulation is achieved through the positive and negative first-order diffracted lights of the acousto-optic modulator based on the Raman-Nath principle, so that laser beams of different frequencies can be diffracted simultaneously by a single acousto-optic modulator. This module effectively overcomes the interference of laser noise and electrical noise by using heterodyne technology. After frequency mixing, the subtraction of laser frequency noise is realized, thereby realizing the output of a dual-frequency light source with high frequency stability. At the same time, the simple structure of a single acousto-optic modulator can realize the miniaturization and integration of the system.

[0006] Furthermore, by making the optical paths of the two diffracted lights of the positive and negative first orders coherent and synthesized by a single acousto-optic modulator, the phase noise is eliminated.

[0007] Furthermore, by making the two diffracted lights of the positive and negative first orders coherent and synthesized by a single acousto-optic modulator, the frequency noise introduced in the signal source, signal transmission, signal amplification, conversion of electrical signals into sound waves, and the process of light diffraction through sound waves is eliminated.

[0008] A high-performance dual-frequency laser generation device based on a single acousto-optic modulator includes a single-frequency laser light source, a mode matcher, a high-precision frequency modulation module, and a polarization control component. The single-frequency laser light source is used to generate fundamental frequency light. After passing through an isolator, the fundamental frequency light passes through a mode matcher for mode matching to ensure the highest diffraction efficiency during the frequency conversion process of the acousto-optic modulator, and then passes through a single acousto-optic modulator to form two polarized lights with shifted frequencies of f +1 and f -1 respectively. Among them, the polarized light with a frequency of f +1 passes through the polarization control component to adjust the polarization state to make it maintain strict polarization orthogonality with the polarized light with a frequency of f -1 . Finally, the two polarized lights are combined to realize the beat frequency superposition of the two polarized lasers, and finally output a dual-frequency laser with high power, high frequency stability, and orthogonal linear polarization.

[0009] Furthermore, the single-frequency laser light source is selected as a high-power narrow linewidth laser, which can ensure a higher output power of the generated dual-frequency laser light source.

[0010] Further, the polarization control component includes a half-wave plate and a polarization beam splitter.

[0011] Furthermore, the polarization control component further includes a high-reflection mirror group for reflecting two polarized lights to the polarization beam splitter for beam combination.

[0012] A high-performance dual-frequency laser generation method based on a single acousto-optic modulator includes the following steps:

[0013] Step 1: Pass the fundamental frequency light generated by the single-frequency laser source through an isolator to prevent laser back reflection from damaging the laser source;

[0014] Step 2: Perform mode matching on the fundamental frequency light through a mode matcher to maximize the diffraction efficiency of the high-precision frequency modulation module;

[0015] Step 3: After the laser beam after mode matching is diffracted by a single acousto-optic modulator in the high-precision frequency modulation module, two polarized lights with different frequency differences are formed;

[0016] Step 4: Adjust the polarization state of one of the frequency-shifted polarized lights through the polarization control component, make it orthogonal to the other polarized light and then combine the beams, and finally form a dual-frequency laser with high power, high frequency stability, and orthogonal linear polarization output.

[0017] Further, the high-precision frequency modulation of the high-precision frequency modulation module is realized by the positive and negative first-order diffracted lights of the acousto-optic modulator based on the Raman-Nath principle. Using a single acousto-optic modulator to simultaneously perform frequency modulation on the fundamental frequency light and making clever use of the Raman-Nath effect, the two frequency-shifted light beams output are generated under the action of the same radio frequency signal source, power amplifier, piezoelectric transducer, and acousto-optic modulator, and the introduced frequency noise is also the same. After coherent combination, the interference of electrical frequency noise is effectively overcome, ensuring that the generated dual-frequency laser source has higher frequency stability.

[0018] Further, the frequency f of the dual-frequency laser beat is:

[0019] f beat =(f +1 -f -1 )

[0020] =(f AOM+ -f AOM- )+(f 1 -f 1 )+(f 2 -f 2 )+(f 3 -f 3 )+(f 4 -f 4 );

[0021] = (f AOM+ - f AOM- )

[0022] where f +1 and f -1 respectively represent the frequencies of the positive and negative first-order diffracted lights output by the acousto-optic modulator, f AOM+ and f AOM- respectively represent the frequencies after the main frequency shift, f 1 and f 1 ' represent the noise introduced by the signal source, f 2 and f 2 ' represent the noise introduced by the time delay of the transmission line, f 3 and f 3 ' represent the noise introduced by the power amplifier during the signal amplification process, f 4 and f 4 ' represent the noise introduced by the piezoelectric transducer during the conversion of the electrical signal into sound waves and the diffraction of light through the acoustic wave medium.

[0023] The high performance of the present invention is mainly reflected in three aspects: high power, high frequency stability, and miniaturization.

[0024] The beneficial effects of the present invention compared with the prior art are as follows:

[0025] (1) High frequency stability: Most of the existing dual-frequency schemes use helium-neon gas lasers, which have a relatively wide linewidth (about 1.5 GHz), affecting the frequency stability of the output laser. The use of different devices in the traditional dual acousto-optic modulation scheme will introduce more frequency noise. However, the present invention adopts the scheme of "high-precision frequency modulation module", and cleverly uses a single acousto-optic modulator based on the Raman-Nath principle to shift the frequency of the fundamental frequency light, and at the same time generates two lasers with different frequencies and other key technologies to improve the frequency stability of the dual-frequency laser source. At the same time, the frequency noise introduced by a single acousto-optic modulator is the same, and these are all important factors for the high frequency stability of the developed dual-frequency laser source. The frequency stability of the dual-frequency laser source realized by the present invention has been improved by 1 to 2 orders of magnitude compared with the prior art.

[0026] (2) High laser source power: The present invention selects a high-power laser and optoelectronic devices with a relatively high power threshold (instead of an atomic gas cell that cannot withstand high power), and obtains a stronger output power than a helium-neon dual-frequency laser. Its power can reach hundreds of milliwatts or even the watt level (the power of a He-Ne laser is usually a few milliwatts). When used with a high-precision frequency modulation module, the most obvious advantage is its high output power and better power stability. It can achieve multi-dimensional measurement with higher measurement accuracy. Multiple devices share a set of laser sources, greatly saving costs. The dual-frequency laser source of the present invention selects the scheme of "high-power laser" and "high-precision frequency modulation module", which can well avoid the above two points.

[0027] (3) More conducive to miniaturization: Compared with the traditional dual acousto-optic modulation method, the single acousto-optic modulation scheme adopted by the present invention significantly reduces the number of required devices. The main structure of its acousto-optic modulator - tellurium dioxide can be integrated behind the resonant cavity of the single-frequency laser and in front of the laser output aperture. The circuit structures such as its piezoelectric transducer are also small in volume, and it can be realized without occupying extra space, thus achieving miniaturization and integration. In this scheme, the product shows significant technical advantages in commercial applications, volume reduction, and integrated design, and realizes a more efficient and compact system construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below with reference to the drawings:

[0029] Figure 1 It is a structural diagram of a high-performance dual-frequency laser generation device based on a single acousto-optic modulator of the present invention;

[0030] Figure 2 It is a schematic diagram of the generation of a high-performance dual-frequency laser based on a single acousto-optic modulator of the present invention;

[0031] Figure 3 It is a flowchart of the implementation of a method for generating a high-performance dual-frequency laser based on a single acousto-optic modulator of the present invention;

[0032] Figure 4 It is a result diagram of the evaluation of the frequency stability of the dual-frequency laser of the present invention;

[0033] In the figure: single-frequency laser source - 1, lens - 2, high-precision frequency modulation module - 3, acousto-optic modulator - 31, power amplifier - 32, radio frequency output signal source - 33, half-wave plate - 4, high-reflection mirror group - 5, first high-reflection mirror - 51, second high-reflection mirror - 52, third high-reflection mirror - 53, fourth high-reflection mirror - 54, fifth high-reflection mirror - 55, beam splitter - 6. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] As Figures 1 to 4As shown in the figure, the present invention proposes a method and device for generating dual-frequency lasers with high frequency stability, high power, support for multi-axis measurement, miniaturization and integration based on a single acousto-optic modulator structure. This method uses a high-power single-frequency laser as the fundamental frequency light, and through precise mode coupling technology, the fundamental frequency light realizes frequency modulation caused by the Raman-Nath effect through a single acousto-optic modulator. This method is based on a unique acousto-optic interaction principle, and generates lasers with multiple modulation frequencies through a single acousto-optic modulator. Further, through beat frequency and beam combination technology, precise control of the frequency difference of the dual-frequency laser source is achieved, ensuring its high-frequency stable output. The core of this technology lies in the ingenious application of a single acousto-optic modulator (Raman-Nath effect). By using heterodyne technology, the interference of laser noise and electrical noise is effectively overcome. After frequency difference, the subtraction of laser frequency noise is realized, thereby realizing the output of a dual-frequency light source with high frequency stability. At the same time, the simple structure of a single acousto-optic modulator can realize the miniaturization and integration of the system. In short, this method and device not only have excellent high-power laser output function, but also show excellent frequency stability, providing a more ideal light source solution for the fields of high-performance laser interferometry and lidar technology, and significantly promoting the progress of related precision measurement and precision manufacturing technologies. Such a light source has broad application prospects in pointing measurement fields such as surveying and mapping, satellite attitude measurement, interstellar exploration, space communication pointing calibration, etc., and in fields such as lithography positioning, machine tool calibration, optical element detection, high-precision measurement, and ultra-high-precision interferometric displacement (or angle) measurement.

[0035] As Figure 1 shown, a high-precision frequency modulation module based on a single acousto-optic modulator in this embodiment includes an acousto-optic modulator 31 based on the Raman-Nath principle, a power amplifier 32, and a radio frequency output signal source 33. The output end of the radio frequency output signal source 33 is connected to the input end of the power amplifier 32, and the output end of the power amplifier 32 is connected to the input end of the acousto-optic modulator 31.

[0036] For the high-precision frequency modulation part, a single acousto-optic modulator 31 is used to simultaneously perform frequency modulation on the fundamental frequency light. The ingenious application of the Raman-Nath effect makes the two output frequency-shifted light beams generated under the action of the same radio frequency signal source, power amplifier, piezoelectric transducer, and acousto-optic modulator, and the introduced frequency noise is also the same. After coherent combination, the interference of electrical frequency noise is effectively overcome, ensuring that the generated dual-frequency laser light source has higher frequency stability and reaches the international leading index.

[0037] As Figure 1 and 2As shown in the figure, a high-performance dual-frequency laser generation device based on single-frequency laser and a single acousto-optic modulator in this embodiment includes a single-frequency laser light source 1 and a high-precision frequency modulation module 3. The single-frequency laser light source 1 is used to generate fundamental frequency light. The fundamental frequency light passes through an isolator and then successively passes through a lens 2 and the high-precision frequency modulation module 3 to form two frequency-shifted light beams f +1 and f -1 . The polarized light with frequency f +1 passes through a half-wave plate 4 and then coherently combines with the polarized light with frequency f -1 through a beam splitter 6 to form a high-power and high-frequency stability orthogonally linearly polarized dual-frequency laser beam.

[0038] After passing through the isolator, the fundamental frequency light undergoes precise mode matching through the lens 2 to ensure the highest diffraction efficiency during the frequency conversion process of the acousto-optic modulator 31. After the fundamental frequency light passes through a single acousto-optic modulator 31, one of the modulated lasers adjusts its polarization state through a half-wave plate 4 to maintain strict polarization orthogonality with the other modulated laser.

[0039] In this embodiment, the single-frequency laser light source 1 selects a high-power narrow-linewidth laser and optoelectronic devices that can withstand a relatively high power threshold (instead of an atomic gas cell that cannot withstand high power), obtaining a stronger output power than a helium-neon dual-frequency laser. This type of laser can provide a new option for the dual-frequency laser preparation scheme. Its laser power output is relatively more stable than that of helium-neon gas lasers, and the power can reach several hundred milliwatts (mW) or even watt (W) levels, ensuring that the generated dual-frequency laser light source has a higher output power and reaches the international leading indicators.

[0040] The device in this embodiment further includes a high-reflection mirror group 5, which is used to reflect the two polarized light beams with different frequencies (f +1 and f -1 ) frequency-shifted by the acousto-optic modulator 31 to the beam splitter 6.

[0041] Specifically, the high-reflection mirror group 5 in this embodiment includes a first high-reflection mirror 51, a second high-reflection mirror 52, a third high-reflection mirror 53, a fourth high-reflection mirror 54, and a fifth high-reflection mirror 55. Among them, the polarized light with frequency f +1 is reflected to the beam splitter 6 after passing through the first high-reflection mirror 51, the half-wave plate 4, the second high-reflection mirror 52, and the third high-reflection mirror 53. The polarized light with frequency f -1 is reflected to the beam splitter 6 after passing through the fourth high-reflection mirror 54 and the fifth high-reflection mirror 55.

[0042] As shown in Figure 2 and 3 , based on the above device, a high-performance dual-frequency laser generation method based on single-frequency laser and a single acousto-optic modulator in this embodiment specifically includes the following steps:

[0043] Step 1: The laser generated by the single-frequency laser light source 1 is mode-matched through the lens 2. The waist spot of the light beam is adjusted by adjusting the position of the lens 2 to maximize the diffraction efficiency of the fundamental frequency light passing through the acousto-optic modulator 31;

[0044] Step 2: The mode-matched laser beam passes through the high-precision frequency modulation module 3 to form two frequency-shifted polarized lights (f +1 and f -1 );

[0045] Step 3: After the polarized light with frequency f +1 passes through the half-wave plate 4, the polarization state is adjusted to be orthogonal to the other polarized light f -1 ;

[0046] Step 4: The two mutually orthogonal polarized lights are reflected by the high-reflection mirror group 5 to the beam splitter 6 to form a high-power and high-frequency stability dual-frequency laser beam with orthogonal linear polarization output.

[0047] The specific method of high-precision frequency modulation is realized by the positive and negative first-order diffracted lights of the acousto-optic modulator 31 based on the Raman-Nath principle. The acousto-optic modulator 31 of this principle can diffract different frequency laser beams simultaneously through a single acousto-optic modulator 31, solving the technical problem that the single acousto-optic modulator based on the Bragg principle cannot generate small frequency difference frequency shift at the same time. At the same time, the problem of insufficient output beam power caused by its low diffraction efficiency is solved by the high-power laser light source.

[0048] Assume that the optical field expression of the incident light is:

[0049]

[0050] In the formula: is the optical field intensity of the incident light at position and time , is the position vector of the incident fundamental frequency optical field in space, t is time, E 0 is the maximum intensity of the incident fundamental frequency optical field, is the propagation direction, ω is the frequency of the incident fundamental frequency light;

[0051] When using the single acousto-optic modulation method to generate dual-frequency laser, its noise mainly considers the noise introduced by the signal source the delay noise introduced during signal transmission the noise introduced by the power amplifier during signal amplification and the noise introduced by the piezoelectric transducer inside the acousto-optic modulator 31 during the conversion of electrical signal into acoustic wave and the diffraction of light through the acoustic wave medium, etc. Among them: E 1The noise intensity of the noise introduced by the signal source coupled to the optical field The propagation direction of the noise introduced by the signal source, E 2 The noise intensity of the delay noise introduced during signal transmission coupled to the optical field The propagation direction of the delay noise introduced during signal transmission, E 3 The noise intensity of the noise introduced by the power amplifier during signal amplification coupled to the optical field The propagation direction of the noise introduced by the power amplifier during signal amplification, E 4 The noise intensity of the noise introduced by the piezoelectric transducer during the conversion of electrical signals into acoustic waves and the diffraction of light through the acoustic wave medium, etc., coupled to the optical field The propagation direction of the noise introduced by the piezoelectric transducer during the conversion of electrical signals into acoustic waves and the diffraction of light through the acoustic wave medium, etc., ω 1 The frequency of the frequency noise introduced by the signal source, ω 2 The frequency of the noise introduced by the transmission delay noise during the transmission process, ω 3 The frequency of the noise introduced by the power amplifier during signal amplification, ω 4 The frequency of the noise introduced by the piezoelectric transducer during the conversion of electrical signals into acoustic waves and the diffraction of light through the acoustic wave medium, etc.

[0052] The ultrasonic field propagates along the direction perpendicular to the acousto-optic crystal, and the noise in terms of amplitude, frequency, phase, etc. is superimposed. Its expression is:

[0053]

[0054] In the formula: Is the noise coupled to the incident fundamental frequency optical field

[0055] Using the ultrasonic field to modulate the optical field, it is expressed as:

[0056]

[0057] In the high-precision frequency modulation module, only consider the frequency ω in the above formula 0 +ω 1 +ω 2 +ω 3 +ω 3 +ω 4 And phase

[0058] For the phase part: In the present invention, by using a single acousto-optic modulator 31, it is ensured that the ±1st order diffraction beams have the same electrical characteristics. At the same time, by ensuring that the optical paths are the same when the two diffraction lights are coherently synthesized, the phase delay of the output dual-frequency laser is made consistent, achieving phase noise immunity.

[0059] For the frequency part: the noise f introduced by the signal source 1 (ω 1 = 2πf 1 ), the same acousto-optic modulator 31 simultaneously performs positive and negative frequency modulation on the fundamental frequency light, and the same transmission line ensures that the frequency noise f 2 (ω 2 = 2πf 2 ) introduced by the transmission delay is exactly the same. The same power amplifier ensures that the noise f 3 (ω 3 = 2πf 3 ) introduced during the signal amplification process and the noise f 4 (ω 4 = 2πf 4 ) introduced by the same piezoelectric transducer during the conversion of electrical signals into acoustic waves and the diffraction of light through the acoustic wave medium, etc. are also exactly the same.

[0060] After the fundamental frequency light is frequency-shifted by acousto-optic modulation, the frequency component can be expressed as:

[0061] f -1 = f AOM- + f 1 + f 2 + f 3 + f 4 +;

[0062] f +1 = f AOM+ + f 1 '+ f 2 '+ f 3 '+ f 4 '+...;

[0063] Where f +1 , f -1 respectively represent the frequencies of the positive and negative first-order diffracted lights output by the acousto-optic modulator, f AOM+ , f AOM- respectively represent the frequencies after the main frequency is frequency-shifted, f 1 and f 1 ' represent the noise introduced by the signal source, f 2 and f 2 ' represent the noise introduced by the transmission line delay, f 3 and f 3 ' represent the noise introduced by the power amplifier during the signal amplification process, f 4 and f 4 ' represent the noise introduced by the piezoelectric transducer during the conversion of electrical signals into acoustic waves and the diffraction of light through the acoustic wave medium, etc.

[0064] After the two polarized lights are coherently synthesized, the dual-frequency laser f beatThe frequency can be expressed as:

[0065] f beat =|f +1 -f -1 |=|(f AOM+ -f AOM- )+(f 1 -f 1 )+(f 2 -f 2 )+(f 3 -f 3 )+(f 4 -f 4 ')+…|。

[0066] Since the frequency shift is carried out on the same acou-optic modulator 31, the frequency noise sources of the two modulated laser beams can be partially completely cancelled out, that is, (f 1 =f 1 '), (f 2 =f 2 '), (f 3 =f 3 '), (f 4 =f 4 '). Therefore, the frequency noise of the double-frequency laser output after coherent combination is lower, ensuring the frequency stability of the double-frequency laser output.

[0067] Therefore, the frequency of the double-frequency laser f beat is written as:

[0068] f beat =|f AOM+ -f AOM- |。

[0069] Based on the above technical solution, the frequency measurement result of the double-frequency laser of the present invention is as Figure 4 shown. From Figure 4 it can be clearly observed that the frequency stability of the double-frequency laser of the present invention is measured by using a frequency meter, and at the same time, the measurement result is analyzed by using the Allan variance. After calculation, the theoretical Allan variance is: σ y (τ)≈2.75×10 -11 。

[0070] Compared with the solutions mentioned in the background art, the dual-frequency laser generated by the acousto-optic modulator solution based on a single Raman-Nath principle in the present invention exhibits some unique advantages. Compared with the traditional dual acousto-optic frequency shift (Bragg principle), this solution can generate two laser beams with different frequencies simultaneously. The noise sources of the two beams are the same, and the synergism is stronger. Therefore, the difference frequency stability of the output dual-frequency laser is better, and the simplification of the device is also conducive to the miniaturization and integration of the light source. Different from the traditional helium-neon type dual-frequency generation solution, its advantages are more obvious: high-frequency stable dual-frequency laser output, high-power dual-frequency laser output, laser type immunity, further miniaturization and integration, and support for simultaneous multi-dimensional and multi-axis measurement. The present invention can improve the frequency stability of the light source, promote the reduction of measurement errors related to frequency stability, and provide new and more precise possibilities for the application of dual-frequency laser technology in higher-precision precision measurement.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision frequency modulation module based on a single acousto-optic modulator, characterized by: The invention comprises a single acousto-optic modulator based on the Raman-Nyess principle, a power amplifier and a radio frequency output signal source. The output end of the radio frequency output signal source is connected to the input end of the power amplifier, and the output end of the power amplifier is connected to the input end of the acousto-optic modulator. High-precision frequency modulation is achieved by positive and negative first-order diffracted light of the acousto-optic modulator based on the Raman-Nyess principle, so that laser beams of different frequencies are simultaneously diffracted by the single acousto-optic modulator.

2. The high-precision frequency modulation module based on a single acousto-optic modulator according to claim 1, characterized in that: A single acousto-optic modulator is used to make the two diffracted lights of the positive and negative order coherently combined so that the optical path is consistent, thus eliminating phase noise.

3. The high-precision frequency modulation module based on a single acousto-optic modulator according to claim 1, characterized in that: By using a single acousto-optic modulator, the two diffracted light beams of the positive and negative orders are coherently combined to eliminate the frequency noise introduced in the signal source, signal transmission, signal amplification, conversion of electrical signals into sound waves, and the diffraction process of light through sound waves.

4. A high-performance dual-frequency laser generating device based on a single acousto-optic modulator, characterized in that: The invention comprises a single-frequency laser light source, a mode matcher, a high-precision frequency modulation module as claimed in any one of claims 1 to 3, and a polarization control component, wherein the single-frequency laser light source is used to generate fundamental frequency light, and the fundamental frequency light passes through an isolator and then passes through a mode matcher for mode matching to ensure that the diffraction efficiency of the acousto-optic modulator is the highest during the frequency conversion process, and then passes through a single acousto-optic modulator to form two beams with frequencies f and f respectively after frequency shifting. +1 and f -1 Polarized light with a frequency of f +1 The polarized light passes through the polarization control component to adjust the polarization state so that it is consistent with the frequency f -1 The polarized light maintains strict polarization orthogonality, and finally the two polarized light beams are combined to achieve the beat frequency superposition of the two polarized laser beams, and finally output a dual-frequency laser with high power, high frequency stability and orthogonal linear polarization.

5. A high-performance dual-frequency laser generating device based on a single acousto-optic modulator according to claim 4, characterized in that: The single-frequency laser light source is a high-power narrow-linewidth laser.

6. A high-performance dual-frequency laser generating device based on a single acousto-optic modulator according to claim 4, characterized in that: The polarization control assembly includes a half wave plate and a polarization beam splitter.

7. A high-performance dual-frequency laser generating device based on a single acousto-optic modulator according to claim 6, characterized in that: The polarization control component also includes a high-reflection mirror group for reflecting two polarized light beams to the polarization beam splitter for beam combination.

8. A method for generating dual-frequency laser using the high-performance dual-frequency laser generating device based on a single acousto-optic modulator as claimed in any one of claims 4 to 7, characterized in that: The following steps are involved: Step 1: Pass the fundamental frequency light generated by the single-frequency laser light source through the isolator; Step 2: Perform pattern matching on the fundamental frequency light through a pattern matcher so that the diffraction efficiency of the fundamental frequency light passing through the high-precision frequency modulation module is the highest; Step 3: The mode-matched laser beam is diffracted by a single acousto-optic modulator in a high-precision frequency modulation module to form two polarized lights with different frequency differences; Step 4: After one of the frequency-shifted polarized lights is adjusted in polarization state by a polarization control component, it is made orthogonal to the other polarized light and then combined to form a dual-frequency laser with high power, high frequency stability and orthogonal linear polarization output.

9. The high-performance dual-frequency laser generation method based on a single acousto-optic modulator according to claim 8, characterized in that: The high-precision frequency modulation module performs high-precision frequency modulation through the positive and negative first-order diffraction light of the acousto-optic modulator based on the Raman-Nesse principle.

10. The high-performance dual-frequency laser generation method based on a single acousto-optic modulator according to claim 9, characterized in that: The frequency of the dual-frequency laser is f beat for: f beat =(f +1 -f -1 ) <h2 style=";text-align:left;direction:ltr">(f)<h2 style=";text-align:left;direction:ltr"> AOM+ <h2 style=";text-align:left;direction:ltr"> -f<h2 style=";text-align:left;direction:ltr"> AOM- <h2 style=";text-align:left;direction:ltr"> )+(f1-f1')+(f2-f2')+(f3-f3')+(f4-f4'); =(f AOM+ -f AOM- ) where f +1 、f -1 They represent the frequencies of the positive and negative first-order diffracted light output by the AOM, respectively. AOM+ 、f AOM- They represent the frequencies after the main frequency is shifted, f1 and f1' represent the noise introduced by the signal source, f2 and f2' represent the noise introduced by the transmission line delay, f3 and f3' represent the noise introduced by the power amplifier in the process of signal amplification, and f4 and f4' represent the noise introduced by the piezoelectric transducer when the electrical signal is converted into sound waves and the light is diffracted through the acoustic medium.

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