CN110764286B - A laser beam combining method based on acousto-optic anomalous Bragg diffraction - Google Patents

Abstract

The invention discloses a laser beam combining method based on acousto-optic anomalous Bragg diffraction, belonging to the field of laser beam combining. Intersection point: According to the number of incident light wavelengths, the number of incident beams, the number of incident beams with the same wavelength, and the intersection of the multiple waves with the target diffraction angle, obtain the frequency of the acoustic wave on the diffraction angle curve of the acousto-optic Dixon equation and the incident angle of the incident beam; the acoustic wave is loaded on the acousto-optic crystal, and the incident beam is incident into the acousto-optic crystal at the incident angle; the incident beam and the acoustic wave undergo anomalous Bragg diffraction to form a composite wave with the target diffraction angle. The invention can precisely control the propagation direction of the combined wave by selecting the frequency of the sound wave and adjusting the incident angle of the incident beam.

Description

A laser beam combining method based on acousto-optic anomalous Bragg diffraction

technical field

The invention belongs to the field of laser beam combining, and more particularly relates to a laser beam combining method based on acousto-optic anomalous Bragg diffraction.

Background technique

Since the generation of laser, laser beam combining technology has been an important research content. The laser beam combining of the same optical wavelength solves the problem of beam quality degradation when the laser output power is very high. The laser beam combining technology of different optical wavelengths also plays an extremely important role in the wavelength division multiplexing technology of optical communication technology.

The existing laser beam combining methods include coherent beam combining and incoherent beam combining. The realization conditions of coherent beam combining are very strict, and it is not easy to realize. Incoherent beam combining methods include wavelength combining, polarization combining, fiber combining, grating combining, etc., as well as complex combining structures invented based on the above structures, all of which are passive devices. Change; the angle of incident light in polarization beam combining is fixed, and the polarization states must be perpendicular to each other; there is a beam quality problem in fiber beam combining, and the beam quality is improved by various methods, but the structure complexity is increased; the grating beam combining method has a fixed angle of incident light, and The beam combination of the same wavelength cannot be realized.

The CN 201480058835 patent proposes to use acousto-optic interaction to combine beams, but it does not specify the necessary conditions for using acousto-optic beam combination, only anomalous Bragg diffraction can be used, and at least one of the two beams is o-light of a crystal. And the patent only describes the beam combining under the condition of different polarization states of the incident light, the beam combining conditions are relatively fixed, and the frequency of the loaded acoustic wave cannot be changed in a large range. cost.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the purpose of the present invention is to provide a laser beam combining method based on acousto-optic anomalous Bragg diffraction, aiming to solve the problem that the existing beam combining passive devices cannot control the propagation direction of the outgoing beam.

To achieve the above object, the present invention provides a laser beam combining method based on acousto-optic anomalous Bragg diffraction, comprising:

(1) According to the diffraction curve of the acousto-optic Dixon equation corresponding to each incident light wavelength, determine the multiple-wave intersection point with the target diffraction angle;

(2) According to the number of incident light wavelengths, the number of incident beams, the number of incident beams with the same wavelength, and the multiplex intersection point with the target diffraction angle, obtain the acoustic wave on the acousto-optic Dixon equation diffraction angle curve the frequency and the angle of incidence of the incident beam;

(3) The acoustic wave is loaded on the acousto-optic crystal, and the incident beam is incident on the acousto-optic crystal at the incident angle;

(4) Anomalous Bragg diffraction occurs between the incident beam and the acoustic wave, forming a composite wave with the target diffraction angle;

Among them, the target diffraction angle is greater than the maximum extremum diffraction angle of the acousto-optic Dixon equation diffraction curve; the acousto-optic Dixon equation diffraction curves are all +1 order anomalous Bragg diffraction or -1 order anomalous Bragg diffraction; The light beams all have the o light polarization state of the acousto-optic crystal; i≥1.

Preferably, in step (2), if the number of incident light wavelengths is 1 and the number of incident light beams is 2, the acoustic wave frequency with the target diffraction angle and the corresponding incident light beam are obtained on the acousto-optic Dixon equation diffraction angle curve. angle of incidence.

Preferably, in step (2), if the number of wavelengths of incident light is greater than 1 and equal to the number of incident beams, the frequency of the acoustic wave with the target diffraction angle and the corresponding incident light are obtained on each diffraction angle curve of the acousto-optic Dixon equation. The angle of incidence of the beam.

Preferably, if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of incident beams, the incident beams with the same wavelength are less than or equal to 2, and there is a multi-wave intersection with the target diffraction angle, step (2) ) specifically includes:

(2.1) According to the target diffraction angle and the diffraction angle curve of the acousto-optic Dixon equation, randomly select the acoustic wave frequencies corresponding to i multiple-wave intersection points and the incidence angles of 2i incident beams in the multiple-wave intersection points with the target diffraction angle;

(2.2) On the diffraction angle curve of the acousto-optic Dixon equation of the wavelength corresponding to the remaining incident beam, take one acoustic wave frequency and the corresponding incident angle of the incident beam.

Preferably, if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of incident beams, the incident beams with the same wavelength are less than or equal to 2, and there is no multi-wave intersection point with the target diffraction angle, in each case On the diffraction angle curve of the acousto-optic Dixon equation corresponding to the wavelength of the incident beam, an acoustic wave frequency with a target diffraction angle and an incident angle corresponding to the incident beam are taken.

Preferably, the incident angle of the incident light beam is the Bragg angle;

Preferably, the acoustic wave in which anomalous Bragg diffraction occurs is a shear wave;

Preferably, multiple incident light beams with the same wavelength are combined in a cascade manner, and a polarization converter is arranged between adjacent acousto-optic crystals;

Preferably, if the number of wavelengths of incident light is greater than 1, the number of wavelengths of incident light is not equal to the number of incident beams, the incident beams with the same wavelength are less than or equal to 2, and when there is a multiplexing intersection with the target diffraction angle, select all The frequency of the acoustic wave corresponding to the wave intersection point and the incident angle of the incident beam;

Preferably, the diffraction efficiency of anomalous Bragg diffraction between the incident beam and the acoustic wave is adjusted by adjusting the power of the acoustic waves of different frequencies, so as to control the energy ratio of the combined beam.

Through the above technical solutions conceived by the present invention, compared with the prior art, the following beneficial effects can be achieved:

(1) the present invention utilizes the acousto-optic Dixon equation diffraction curve to determine the frequency of the acoustic wave and the incident angle of the incident beam according to the target diffraction angle, the number of each incident light wavelength and the number of incident beams; Determine the acoustic wave loaded on the acousto-optic crystal, and determine the angle between the incident beam and the acousto-optic crystal according to the incident angle. The acoustic wave and the incident beam undergo anomalous Bragg diffraction, and the composite wave of the target diffraction angle can be obtained. Therefore, by selecting the acoustic wave The frequency and the adjustment of the incident angle of the incident beam can precisely control the propagation direction of the composite wave.

(2) The present invention can control the diffraction efficiency of the anomalous Bragg diffraction between the incident beam and the acoustic wave by controlling the power of the acoustic waves of different frequencies, thereby obtaining diffracted beams with different energy ratios.

Description of drawings

Fig. 1 is the acousto-optic Dixon equation diffraction curve under the abnormal Bragg diffraction provided by the invention;

Fig. 2 is the beam combining situation of two incident beams with the same wavelength provided by embodiment 1;

Fig. 3 is the beam combining situation of two incident beams with different wavelengths provided by embodiment 2;

FIG. 4 is a case of performing acousto-optic combination of three beams with different wavelengths provided in Embodiment 3. FIG.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

The anomalous acousto-optic interaction can be described by the Dixon equation. Taking the tellurium oxide acousto-optic crystal as an example, the Dixon equation is as follows:

Among them, θ _a is the angle between the acoustic wave deviating from the tellurium oxide t-axis ([110] direction), which is called the acoustic off-axis angle; θ _i is the angle between the incident beam deviating from the tellurium oxide z-axis (optical axis), which is called the incident angle ; θ _d is the angle at which the diffracted light deviates from the z-axis (optical axis) of the tellurium oxide, which is called the diffraction angle; λ is the wavelength of the incident light; _f is the frequency of the sound wave; function of angle; n _o and n _e are the refractive indices of o light and e light, respectively; δ is the optical rotation;

Among them, the frequency of the sound wave is the independent variable, and the incident angle, the diffraction angle and the sound off-axis angle are the dependent variables. Since there are only two equations, one angle must be given to study the relationship between the other two angles and the frequency of the acoustic wave under the condition that the momentum matching is satisfied, as shown in Figure 1, that is, when θ _a = 0, the ±1 order The diffracted light satisfies the relationship between the incident angle and the diffraction angle with the frequency of the acoustic wave under the momentum matching.

It can be seen from Figure 1 that the diffraction angle curve of ±1st-order diffracted light has extreme values, that is, there are two incident beams with different transmission directions after passing through the acousto-optic crystal with the same diffraction angle, corresponding to two different optimal acoustic wave frequencies, that is, loading two Sound waves with different frequencies can achieve beam combining effect.

More specifically, when there are two acoustic waves of different frequencies in the acousto-optic crystal, according to the Bragg relationship, there are two different Bragg incident angles, and the two incident beams enter the crystal at different Bragg angles, and interact with the corresponding acoustic waves to generate For diffracted light, anomalous Bragg diffraction is required to make the diffracted light transmit in the same direction.

The invention provides a laser beam combining method based on acousto-optic anomalous Bragg diffraction, comprising:

(1) According to the diffraction curve of the acousto-optic Dixon equation corresponding to each incident light wavelength, determine the multiple-wave intersection point with the target diffraction angle;

(2) According to the number of incident light wavelengths, the number of incident beams, the number of incident beams with the same wavelength, and the multiplex intersection point with the target diffraction angle, obtain the acoustic wave on the acousto-optic Dixon equation diffraction angle curve the frequency and the angle of incidence of the incident beam;

(3) The acoustic wave is loaded on the acousto-optic crystal, and the incident beam is incident on the acousto-optic crystal at the incident angle;

(4) Anomalous Bragg diffraction occurs between the incident beam and the acoustic wave, forming a composite wave with the target diffraction angle;

Among them, the target diffraction angle is greater than the maximum extremum diffraction angle of the acousto-optic Dixon equation diffraction curve; the acousto-optic Dixon equation diffraction curves are all +1 order anomalous Bragg diffraction or -1 order anomalous Bragg diffraction; The light beams all have the o light polarization state of the acousto-optic crystal;

Preferably, in step (2), if the number of incident light wavelengths is 1 and the number of incident light beams is 2, the acoustic wave frequency with the target diffraction angle and the corresponding incident light beam are obtained on the acousto-optic Dixon equation diffraction angle curve. angle of incidence.

Preferably, in step (2), if the number of wavelengths of incident light is greater than 1 and equal to the number of incident beams, the frequency of the acoustic wave with the target diffraction angle and the corresponding incident light are obtained on each diffraction angle curve of the acousto-optic Dixon equation. The angle of incidence of the beam.

Preferably, if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of incident beams, the incident beams with the same wavelength are less than or equal to 2, and there is a multi-wave intersection with the target diffraction angle, step (2) ) specifically includes:

(2.1) According to the target diffraction angle and the diffraction angle curve of the acousto-optic Dixon equation, randomly select the acoustic wave frequencies corresponding to i multiple-wave intersection points and the incidence angles of 2i incident beams in the multiple-wave intersection points with the target diffraction angle;

(2.2) On the acousto-optic Dixon equation diffraction angle curve corresponding to the wavelength of the remaining incident beam, take one acoustic wave frequency and one incident angle of the corresponding incident beam; among them, i≥1.

Preferably, if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of incident beams, the incident beams with the same wavelength are less than or equal to 2, and there is no multi-wave intersection point with the target diffraction angle, in each case On the diffraction angle curve of the acousto-optic Dixon equation corresponding to the wavelength of the incident beam, an acoustic wave frequency with a target diffraction angle and an incident angle corresponding to the incident beam are taken.

Preferably, the incident angle of the incident light beam is the Bragg angle.

Preferably, the acoustic waves that undergo anomalous Bragg diffraction are shear waves.

Preferably, multiple incident light beams with the same wavelength are combined in a cascade manner, and a polarization converter is arranged between adjacent acousto-optic crystals.

Preferably, if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of the incident beams, the incident beams with the same wavelength are less than or equal to 2, and there is a multi-wave intersection with the target diffraction angle, select The acoustic frequency and the incident angle of the incident beam corresponding to all the multiplex intersection points.

Preferably, the diffraction efficiency of anomalous Bragg diffraction between the incident beam and the acoustic wave is adjusted by adjusting the power of the acoustic waves of different frequencies, so as to control the energy ratio of the combined beam.

The more specific scheme of the present invention is as follows:

(1) When the number of incident light wavelengths m is 1, if the number of incident light beams n is 2, go to step (6); when the number of incident light wavelengths m is greater than 1, determine whether the incident light wavelength number m is equal to the incident light The number of beams n, if equal, go to step (5), otherwise go to step (2);

(2) When the number n of incident beams with the same wavelength is less than or equal to 2, if there is no multiplex intersection with the target diffraction angle on the diffraction angle curve of the acousto-optic Dixon equation, go to step (7), otherwise go to step (7) to step (3);

(3) According to the target diffraction angle and the diffraction angle curve of the acousto-optic Dixon equation, randomly select the acoustic wave frequencies corresponding to the i multiplex intersection points and the incidence angles of the 2i incident beams in the multiplex intersection points with the target diffraction angle; wherein, i≥1;

(4) For the remaining (n-2i) incident beams, take one acoustic wave frequency and the incident angle of the corresponding incident beam on the acousto-optic Dixon equation diffraction angle curve corresponding to its wavelength, and go to step (8);

(5) on each acousto-optic Dixon equation diffraction angle curve, select respectively 1 acoustic wave frequency that makes diffracted light angles identical and the incident angle of corresponding 1 incident beam, go to step (8);

(6) on the wavelength-corresponding acousto-optic Dixon equation diffraction angle curve, select 2 acoustic wave frequencies that make diffracted light angles identical and the incident angles corresponding to 2 incident beams, and go to step (8);

(7) on each acousto-optic Dixon equation diffraction angle curve, take an acoustic wave frequency with the target diffraction angle and the incident angle of the corresponding incident beam and go to step (8);

(8) The n incident beams are incident on the acousto-optic crystal at the corresponding incident angle, and (n-i) acoustic waves of different frequencies are loaded on the acousto-optic crystal;

(9) Anomalous Bragg diffraction occurs between the incident beam and the acoustic wave, forming a composite wave with the target diffraction angle.

It should be pointed out that reducing the number of sound waves with different frequencies loaded on the acousto-optic crystal is beneficial to reduce the intermodulation phenomenon of sound waves and the modulation of beam intensity. Generally, the number of sound waves is less than or equal to 3; The corresponding upper limit of the number of incident beams is reduced.

When the wavelength of the incident beam is different, loading the acoustic wave with the frequency corresponding to the intersection of the diffraction angle curve of the acousto-optic Dixon equation in the acousto-optic crystal can reduce the number of the acoustic wave under the condition that the number of the incident beam remains unchanged;

In practical applications, reducing the influence of acoustic intermodulation is also more concerned. The following introduces several methods that are conducive to reducing acoustic intermodulation.

First, the center frequency of the acousto-optic crystal is located in a narrow bandwidth region, which is beneficial to reduce the influence of the intermodulation of the acoustic wave, so as to design the corresponding acousto-optic crystal.

Second, under the condition that other conditions remain unchanged, increasing the frequency interval of the acousto-optic crystal loaded with sound waves is beneficial to reduce the influence of sound wave intermodulation.

Third, when other conditions remain unchanged, reducing the length of the acousto-optic crystal transducer is conducive to reducing the influence of acoustic intermodulation. However, the length of the transducer must make the acousto-optic interaction enter the Bragg diffraction region, that is, the length of the transducer cannot be infinitely reduced;

The laser beam combining method based on acousto-optic anomalous Bragg diffraction provided by the present invention will be described below with reference to the embodiments.

Example 1

As shown in FIG. 2 , Embodiment 1 provides two incident light beams with the same wavelength (that is, the number of incident light beams is n=2, and the incident light wavelength is m=1) for acousto-optic beam combining;

Selecting the target diffraction angle as 9.753°, according to the target diffraction angle of the combined wave and an acousto-optic Dixon equation diffraction angle curve, obtain two acoustic wave frequencies f ₁ and f ₂ that make the diffracted light angles the same: 70MHz, 93.27 The optimum incident angles θ _i1 and θ _i2 of MHz and the corresponding two incident beams are: 6.784° and 5.797°, respectively; the two incident beams are incident on the acousto-optic crystal loaded with 70MHz and 93.27MHz acoustic waves at angles of 6.784° and 5.797°. Anomalous Bragg diffraction occurs, forming a composite wave with a diffraction angle of 9.753°;

Among them, the incident light wavelength λ is 1064 nm, the acousto-optic crystal is tellurium oxide, the polarization state is the o light of the tellurium oxide crystal, and the angle θ _a between the transmission direction of the acoustic wave of the tellurium oxide acousto-optic crystal and the [110] direction of the tellurium oxide crystal is 6.2911 °, using +1st order diffracted light;

Further, if the target diffraction angle becomes 9.753°, then the selected two acoustic wave frequencies f ₁ and f ₂ with the same diffracted light angle become 60MHz, 113.5MHz respectively, and the optimal incident angle θ _i1 corresponding to the two incident lights. , θ _i2 are 7.426° and 5.222°, respectively.

Example 2

As shown in FIG. 3, Embodiment 2 provides a situation in which two incident light beams with different wavelengths (that is, the number of incident light beams is n=2, and the incident light wavelength is m=2) perform acousto-optic beam combining;

Select the target diffraction angle to be 10.06°, collect the diffraction angle of one intersection point corresponding to the diffraction angle curve of the acousto-optic Dixon equation, find that the diffraction angle of the intersection point is different from the target diffraction angle, and select 2 acoustic wave frequencies f ₁ that make the diffracted light angles the same , f ₂ is 140MHz, 120MHz respectively, and the optimal incident angles θ _i1 and θ _i2 of the corresponding two incident beams are 7.223°, 4.971°, respectively. Abnormal Bragg diffraction occurs on the acousto-optic crystal, forming a composite wave with a diffraction angle of 10.06°;

Among them, the wavelengths λ ₁ and λ ₂ of the light waves are 532 nm and 1064 nm, the acousto-optic crystal is tellurium oxide, the polarization state is the o light of the tellurium oxide crystal, and the transmission direction of the acoustic wave of the tellurium oxide acousto-optic crystal is sandwiched between the [110] direction of the tellurium oxide crystal. The angle θ _a is: 6.2911°, using +1st order diffracted light;

Further, if the selected target diffraction angle becomes 10.21°, the diffraction angle at one intersection of the diffraction angle curve of the acousto-optic Dixon equation is collected, and it is found that the diffraction angle of the intersection is the same as the target incident angle, and the acoustic wave frequency f of the intersection is selected. It becomes 129.8MHz, and the two incident beams are incident on the acousto-optic crystal at 7.223° and 4.971°. At the same time, the acousto-optic crystal is loaded with a 129.8MHz sound wave. The incident light wave and the sound wave undergo anomalous Bragg diffraction. Combined.

Example 3

As shown in FIG. 4 , Embodiment 3 provides a situation in which three incident light beams with different wavelengths (that is, the number of incident light beams is n=3, and the incident light wavelength is m=3) perform acousto-optic beam combining;

The selected target diffraction angle is 10.06°, and the diffraction angles of the three intersection points corresponding to the diffraction angle curve of the acousto-optic Dixon equation are collected. It is found that the diffraction angle of the intersection point is different from the target diffraction angle, and three acoustic frequencies are selected to make the diffracted light angles the same. f ₁ , f ₂ and f ₃ are 140MHz, 120MHz and 111.2MHz, and the optimal incident angles θ _i1 , θ _i2 and θ _i3 corresponding to 2 beams of incident light are: 7.223°, 4.971° and 7.406°, respectively, with 3 beams incident The light is incident on the acousto-optic crystal at the above-mentioned incident angles of 7.223°, 4.971° and 7.406°, and the acousto-optic crystal is loaded with the sound waves of the above three frequencies (140MHz, 120MHz and 111.2MHz), and the incident beam and the sound wave have anomalous Bragg diffraction. The combination of the target diffraction angle;

Among them: the incident light wavelengths λ ₁ , λ ₂ and λ ₃ are 532 nm, 1064 nm and 632.8 nm, the acousto-optic crystal is tellurium oxide, the polarization state is the o light of the tellurium oxide crystal, the transmission direction of the acoustic wave of the tellurium oxide acousto-optic crystal and the tellurium oxide The included angle θ _a of the crystal [110] direction is: 6.2911°, and the +1st order diffracted light is used;

Further, if the selected target diffraction angle becomes 10.21°, the diffraction angles at the three intersection points of the diffraction angle curve of the acousto-optic Dixon equation under a certain sound propagation direction are collected, and it is found that there is a diffraction angle at the intersection point and the target incident angle. In the same way, the acoustic wave frequency f ₁ of an intersection point with the same diffraction angle is selected as 129.8MHz, and the remaining acoustic wave frequency f ₂ is selected as 103.8MHz on the remaining acousto-optic Dixon equation diffraction curves, and the maximum frequency corresponding to the three incident beams is 103.8MHz. The optimum incident angles θ _i1 , θ _i2 and θ _i3 are 7.577°, 4.702° and 7.746° respectively; the three incident beams are incident on the acousto-optic crystal at the above incident angles of 7.577°, 4.702° and 7.746°, and the acousto-optic crystal is loaded with the above For acoustic waves with two frequencies (129.8MHz, 103.8MHz), anomalous Bragg diffraction occurs between the incident beam and the acoustic wave, forming a composite wave with a diffraction angle of 10.21°.

To sum up, according to the target diffraction angle, the number of incident light wavelengths and the number of incident beams, the present invention uses the acousto-optic Dixon equation diffraction curve to determine the frequency of the acoustic wave and the incident angle of the incident beam; The frequency of the acoustic wave determines the acoustic wave loaded on the acousto-optic crystal, and the angle between the incident beam and the acousto-optic crystal is determined according to the incident angle. Anomalous Bragg diffraction occurs between the acoustic wave and the incident beam, and the composite wave of the target diffraction angle can be obtained. Selecting the frequency of the acoustic wave and adjusting the incident angle of the incident beam can precisely control the propagation direction of the combined wave.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (10)

1. a laser beam combining method based on acousto-optic anomalous Bragg diffraction, is characterized in that, comprises: Step (1) according to the acousto-optic Dixon equation diffraction curve corresponding to each incident light wavelength, determine the multiplex intersection point with the target diffraction angle; Step (2) According to the number of incident light wavelengths, the number of incident light beams, the number of incident light beams with the same wavelength, and the multi-wave intersection point with the target diffraction angle, acquire the acoustic wave on the acousto-optic Dixon equation diffraction angle curve the frequency and the incident angle of the incident beam; Step (3) loading the acoustic wave on the acousto-optic crystal, and the incident light beam is incident on the acousto-optic crystal at the incident angle; Step (4) abnormal Bragg diffraction occurs between the incident light beam and the acoustic wave to form a composite wave with a target diffraction angle; Among them, the target diffraction angle is greater than the maximum extremum diffraction angle of the acousto-optic Dixon equation diffraction curve; the acousto-optic Dixon equation diffraction curves are all +1 order anomalous Bragg diffraction or -1 order anomalous Bragg diffraction; The light beams all have the o light polarization state of the acousto-optic crystal. 2. The laser beam combining method according to claim 1, wherein in the step (2), if the number of wavelengths of the incident light is 1 and the number of the incident light beams is 2, in the acousto-optical The frequency of the acoustic wave with the target diffraction angle and the incident angle of the corresponding incident light beam are obtained from the diffraction angle curve of the Dixon equation. 3. The laser beam combining method according to claim 1, wherein, in the step (2), if the number of wavelengths of the incident light is greater than 1 and equal to the number of the incident light beams, in each sound The frequency of the acoustic wave with the target diffraction angle and the incident angle of the corresponding incident beam are obtained on the diffraction angle curve of the optical Dixon equation. 4. The laser beam combining method according to claim 1, wherein if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of the incident beams, and the number of wavelengths of the incident light is not equal to When the incident light beam is less than or equal to 2, and there is a multiplexing intersection with the target diffraction angle, the step (2) specifically includes: (2.1) According to the target diffraction angle and the diffraction angle curve of the acousto-optic Dixon equation, randomly select the acoustic wave frequencies corresponding to i multiple-wave intersection points and the incidence angles of 2i incident beams in the multiple-wave intersection points with the target diffraction angle; (2.2) For the remaining incident beam, take one acoustic wave frequency and the corresponding incident angle of the incident beam on the diffraction angle curve of the acousto-optic Dixon equation corresponding to its wavelength, where i≥1. 5. The laser beam combining method according to claim 1, wherein if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of the incident beams, and the number of wavelengths of the incident light is not equal to the number of the incident light beams. When the incident beam is less than or equal to 2, and there is no multi-wave intersection point with the target diffraction angle, on the diffraction angle curve of the acousto-optic Dixon equation corresponding to the wavelength of each incident beam, take an acoustic wave frequency with the target diffraction angle and the corresponding incident beam. The angle of incidence of the beam. 6 . The laser beam combining method according to claim 1 , wherein the incident angle of the incident beam is the Bragg angle. 7 . 7 . The laser beam combining method according to any one of claims 1 to 5 , wherein the acoustic wave that undergoes anomalous Bragg diffraction is a shear wave. 8 . 8 . The laser beam combining method according to claim 1 , wherein the multiple incident beams with the same wavelength are combined in a cascade manner. 9 . 9. The laser beam combining method according to claim 4, wherein if the number of wavelengths of the incident light is greater than 1, the number of wavelengths of the incident light is not equal to the number of the incident beams, and the number of wavelengths of the incident light is not equal to When the incident beam is less than or equal to 2, and there is a multiplex intersection with the target diffraction angle, the acoustic wave frequencies and incident angles of the incident beam corresponding to all the multiplex intersections are selected. 10. laser beam combining method according to claim 1, is characterized in that, the diffraction efficiency that described incident beam and described acoustic wave generate abnormal Bragg diffraction is adjusted by the power of different frequency acoustic waves, realizes the control of combined beam energy ratio .

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