CN110764286B - Laser beam combining method based on acousto-optic anomalous Bragg diffraction - Google Patents
Laser beam combining method based on acousto-optic anomalous Bragg diffraction Download PDFInfo
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/11—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/1086—Beam splitting or combining systems operating by diffraction only
Abstract
The invention discloses a laser beam combining method based on acousto-optic anomalous Bragg diffraction, which belongs to the field of laser beam combining and comprises the following steps: determining a resultant wave intersection point with a target diffraction angle according to an acousto-optic dixon equation diffraction curve corresponding to each incident light wavelength; acquiring the frequency of the sound wave and the incident angle of the incident light beam on the diffraction angle curve of the acousto-optic Dixon equation according to the number of the wavelengths of the incident light, the number of the incident light beams with the same wavelength and the combined wave intersection point with the target diffraction angle; loading sound waves on the acousto-optic crystal, and enabling incident light beams to be incident into the acousto-optic crystal at an incident angle; the incident beam and the sound wave are subjected to abnormal Bragg diffraction to form a composite wave with a target diffraction angle. The invention can accurately control the propagation direction of the composite wave by selecting the frequency of the sound wave and adjusting the incident angle of the incident beam.
Description
Technical Field
The invention belongs to the field of laser beam combination, and particularly relates to a laser beam combination method based on acousto-optic anomalous Bragg diffraction.
Background
Since the generation of laser, the laser beam combining technology has been an important research content. The laser beam combination with the same optical wavelength solves the problem of beam quality reduction caused by high laser output power, and the laser beam combination technology with different optical wavelengths also plays an extremely important role in the wavelength division multiplexing technology of the optical communication technology.
The existing laser beam combination method includes coherent beam combination and incoherent beam combination. The coherent beam combination is difficult to realize due to strict implementation conditions. The incoherent beam combination modes comprise wavelength beam combination, polarization beam combination, optical fiber beam combination, grating beam combination and the like, and the complex hybrid beam structure based on the structure is a passive device, and the combined light wavelength of the wavelength beam combination mode is fixed and cannot be changed; the angle of incident light of the polarized combined beam is fixed, and the polarization states are required to be mutually vertical; the quality of light beams of the optical fiber beam combination is high, but the structural complexity is increased; the incident light angle is fixed in the grating beam combination mode, and the beam combination with the same wavelength cannot be realized.
The CN 201480058835 patent proposes beam combining by acousto-optic interaction, but it does not describe the necessary condition of beam combining by acousto-optic, only employs anomalous bragg diffraction, and at least one of the two beams is o-ray of crystal. And the patent only describes beam combination under the condition that the polarization states of incident light are different, the beam combination condition is relatively fixed, the loaded acoustic wave frequency cannot be changed in a large range, and meanwhile, the patent only mentions that the beam combination is realized by loading one acoustic wave frequency at the cost of loss.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a laser beam combining method based on acousto-optic anomalous Bragg diffraction, and aims to solve the problem that the existing beam combining passive device cannot control the transmission direction of an emergent light beam.
In order to achieve the above object, the present invention provides a laser beam combining method based on acousto-optic anomalous bragg diffraction, which comprises:
(1) determining a resultant wave intersection point with a target diffraction angle according to an acousto-optic dixon equation diffraction curve corresponding to each incident light wavelength;
(2) acquiring the frequency of the sound wave and the incident angle of the incident light beam on the diffraction angle curve of the acousto-optic Dixon equation according to the number of the wavelengths of the incident light, the number of the incident light beams with the same wavelength and the combined wave intersection point with the target diffraction angle;
(3) loading sound waves on the acousto-optic crystal, and enabling incident light beams to be incident into the acousto-optic crystal at an incident angle;
(4) the incident beam and the sound wave are subjected to anomalous Bragg diffraction to form a composite wave with a target diffraction angle;
the target diffraction angle is larger than the maximum extreme value diffraction angle of the acousto-optic Dixon equation diffraction curve; the acousto-optic Dixon equation diffraction curves are all abnormal Bragg diffraction of +1 level or all abnormal Bragg diffraction of-1 level; the incident beams all have an o light polarization state of the acousto-optic crystal; i is more than or equal to 1.
Preferably, in step (2), if the number of wavelengths of the incident light is 1 and the number of incident light beams is 2, the acoustic frequency having the target diffraction angle and the incident angle of the corresponding incident light beam are obtained on the acousto-optic dixon equation diffraction angle curve.
Preferably, in step (2), if the number of wavelengths of the incident light is greater than 1 and equal to the number of incident light beams, the acoustic frequency having the target diffraction angle and the incident angle of the corresponding incident light beam are obtained on each dixon equation diffraction angle curve of the acoustic light.
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 number of incident beams having the same wavelength is less than or equal to 2, and a composite intersection point having a target diffraction angle exists, the step (2) specifically includes:
(2.1) randomly selecting acoustic frequency corresponding to i combined wave intersection points and incident angles of 2i incident beams from the combined wave intersection points with the target diffraction angle according to the target diffraction angle and the diffraction angle curve of the Dixon equation of the acousto-optic;
and (2.2) respectively taking 1 sound wave frequency and the incident angle of the corresponding incident beam on the diffraction angle curve of the acousto-optic Dixon equation of the corresponding wavelength of the residual incident beam.
Preferably, if the number of the wavelengths of the incident light is greater than 1, the number of the wavelengths of the incident light is not equal to the number of the incident beams, the number of the incident beams having the same wavelength is less than or equal to 2, and when there is no composite wave intersection point having the target diffraction angle, 1 sound wave frequency having the target diffraction angle and an incident angle of the corresponding incident beam are respectively taken on the diffraction angle curve of the acousto-optic dixon equation corresponding to the wavelength of each incident beam.
Preferably, the incident angle of the incident light beam is a bragg angle;
preferably, the acoustic wave that is abnormally bragg diffracted is a shear wave;
preferably, a plurality of incident beams with the same wavelength are combined in a cascading mode, and a polarization converter is arranged between adjacent acousto-optic crystals;
preferably, if the number of the wavelengths of the incident light is greater than 1, the number of the wavelengths of the incident light is not equal to that of the incident beams, the number of the incident beams with the same wavelength is less than or equal to 2, and when the multiple wave intersection points with the target diffraction angle exist, the acoustic frequency corresponding to all the multiple wave intersection points and the incident angle of the incident beams are selected;
preferably, the diffraction efficiency of the incident light beam and the acoustic wave with abnormal Bragg diffraction is adjusted through the power of the acoustic wave with different frequencies, so that the energy ratio of the combined light beam is controlled.
Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:
(1) according to the target diffraction angle, the number of incident light wavelengths and the number of incident beams, determining the frequency of a sound wave and the incident angle of the incident beams by using an acousto-optic Dixon equation diffraction curve; the acoustic wave loaded on the acousto-optic crystal is determined according to the calculated acoustic wave frequency, the included angle between the incident beam and the acousto-optic crystal is determined according to the incident angle, the acoustic wave and the incident beam are subjected to abnormal Bragg diffraction, and the resultant wave of the target diffraction angle can be obtained.
(2) The invention can control the diffraction efficiency of the incident beam and the acoustic wave anomalous Bragg diffraction by controlling the power of the acoustic wave with different frequencies, thereby obtaining the diffracted beams with different energy ratios.
Drawings
FIG. 1 is a diffraction curve of acousto-optic Dixon equation under anomalous Bragg diffraction provided by the present invention;
FIG. 2 is a combined beam of two incident beams with the same wavelength provided in example 1;
FIG. 3 is a combined beam of two incident beams with different wavelengths provided in example 2;
FIG. 4 shows the case of performing acousto-optic synthesis of three light beams with different wavelengths provided in example 3.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The anomalous acousto-optic interaction can be described using the dixon equation, which is shown below, for example, with a tellurium oxide acousto-optic crystal:
wherein, thetaaFor acoustic deviation from t-axis of tellurium oxide ([110 ]]Direction), referred to as the off-axis angle of sound; thetaiThe included angle of the incident beam deviating from the z axis (optical axis) of the tellurium oxide is called as the incident angle; thetadThe included angle of the diffracted light deviating from the z axis (optical axis) of the tellurium oxide is called as the diffraction angle; λ is the wavelength of the incident light; f is the acoustic frequency; v (theta)a) Is the velocity of the acoustic wave, as a function of the acoustic off-axis angle; n isoAnd neRefractive indices of o light and e light, respectively; is the optical rotation rate;
wherein, the sound wave frequency is independent variable, and the incidence angle, the diffraction angle and the off-axis angle are dependent variables. Because only two equations are needed, one included angle must be given to study the relationship between the other two included angles and the sound wave frequency under the condition of satisfying momentum matching, as shown in FIG. 1, that is, given thetaaWhen the diffraction angle is 0, the + -1 st order diffraction light satisfies the relationship of the incident angle and the diffraction angle with the acoustic wave frequency under the momentum matching.
As can be seen from FIG. 1, the diffraction angle curve of the + -1 st order diffraction light has an extreme value, that is, the diffraction angles of the incident light beams with two different transmission directions are the same after passing through the acousto-optic crystal, and the beam combination effect can be realized by loading two sound waves with different frequencies corresponding to two different optimal sound wave frequencies.
More specifically, when there are two acoustic waves with different frequencies in the acousto-optic crystal, there are two different bragg incident angles according to the bragg relationship, and two incident beams enter the crystal at different bragg angles and interact with the corresponding acoustic waves to generate diffracted light, so that the transmission directions of the diffracted light are consistent, anomalous bragg diffraction is required.
The invention provides a laser beam combining method based on acousto-optic anomalous Bragg diffraction, which comprises the following steps:
(1) determining a resultant wave intersection point with a target diffraction angle according to an acousto-optic dixon equation diffraction curve corresponding to each incident light wavelength;
(2) acquiring the frequency of the sound wave and the incident angle of the incident light beam on the diffraction angle curve of the acousto-optic Dixon equation according to the number of the wavelengths of the incident light, the number of the incident light beams with the same wavelength and the combined wave intersection point with the target diffraction angle;
(3) loading sound waves on the acousto-optic crystal, and enabling incident light beams to be incident into the acousto-optic crystal at an incident angle;
(4) the incident beam and the sound wave are subjected to anomalous Bragg diffraction to form a composite wave with a target diffraction angle;
the target diffraction angle is larger than the maximum extreme value diffraction angle of the acousto-optic Dixon equation diffraction curve; the acousto-optic Dixon equation diffraction curves are all abnormal Bragg diffraction of +1 level or all abnormal Bragg diffraction of-1 level; the incident beams all have an o light polarization state of the acousto-optic crystal;
preferably, in step (2), if the number of wavelengths of the incident light is 1 and the number of incident light beams is 2, the acoustic frequency having the target diffraction angle and the incident angle of the corresponding incident light beam are obtained on the acousto-optic dixon equation diffraction angle curve.
Preferably, in step (2), if the number of wavelengths of the incident light is greater than 1 and equal to the number of incident light beams, the acoustic frequency having the target diffraction angle and the incident angle of the corresponding incident light beam are obtained on each dixon equation diffraction angle curve of the acoustic light.
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 number of incident beams having the same wavelength is less than or equal to 2, and a composite intersection point having a target diffraction angle exists, the step (2) specifically includes:
(2.1) randomly selecting acoustic frequency corresponding to i combined wave intersection points and incident angles of 2i incident beams from the combined wave intersection points with the target diffraction angle according to the target diffraction angle and the diffraction angle curve of the Dixon equation of the acousto-optic;
(2.2) respectively taking 1 sound wave frequency and the incident angle of the corresponding incident beam on the diffraction angle curve of the acousto-optic Dixon equation of the corresponding wavelength of the residual incident beam; wherein i is more than or equal to 1.
Preferably, if the number of the wavelengths of the incident light is greater than 1, the number of the wavelengths of the incident light is not equal to the number of the incident beams, the number of the incident beams having the same wavelength is less than or equal to 2, and when there is no composite wave intersection point having the target diffraction angle, 1 sound wave frequency having the target diffraction angle and an incident angle of the corresponding incident beam are respectively taken on the diffraction angle curve of the acousto-optic dixon equation corresponding to the wavelength of each incident beam.
Preferably, the incident angle of the incident light beam is a bragg angle.
Preferably, the acoustic wave that is abnormally bragg diffracted is a shear wave.
Preferably, a plurality of incident light beams with the same wavelength are combined in a cascading manner, and a polarization converter is arranged between adjacent acousto-optic crystals.
Preferably, if the number of the wavelengths of the incident light is greater than 1, the number of the wavelengths of the incident light is not equal to the number of the incident beams, the number of the incident beams with the same wavelength is less than or equal to 2, and when a composite wave intersection point with a target diffraction angle exists, the acoustic frequency corresponding to all the composite wave intersection points and the incident angle of the incident beams are selected.
Preferably, the diffraction efficiency of the incident light beam and the acoustic wave with abnormal Bragg diffraction is adjusted through the power of the acoustic wave with different frequencies, so that the energy ratio of the combined light beam is controlled.
The more specific scheme of the invention is as follows:
(1) when the number m of the incident light wavelengths is 1, if the number n of the incident light beams is 2, turning to the step (6); when the number m of the incident light wavelengths is larger than 1, judging whether the number m of the incident light wavelengths is equal to the number n of the incident light beams, if so, turning to the step (5), otherwise, turning to the step (2);
(2) when the number n of incident beams with the same wavelength is less than or equal to 2, if no composite wave intersection point with the target diffraction angle exists on the acousto-optic Dixon equation diffraction angle curve, turning to the step (7), otherwise, turning to the step (3);
(3) randomly selecting acoustic wave frequencies corresponding to i combined wave intersection points and incident angles of 2i incident beams from the combined wave intersection points with the target diffraction angle according to the target diffraction angle and the diffraction angle curve of the acousto-optic Dixon equation; wherein i is more than or equal to 1;
(4) the rest (n-2i) incident beams respectively take 1 sound wave frequency and the incident angle of the corresponding incident beam on the diffraction angle curve of the acousto-optic Dixon equation corresponding to the wavelength of the rest incident beams, and then the step (8) is carried out;
(5) respectively selecting 1 sound wave frequency which enables diffraction light angles to be the same and an incident angle corresponding to 1 incident light beam on each diffraction angle curve of the acousto-optic Dixon equation, and turning to the step (8);
(6) selecting 2 sound wave frequencies which enable diffraction light angles to be the same and incident angles corresponding to 2 incident light beams on a diffraction angle curve of the acousto-optic Dixon equation corresponding to the wavelength, and turning to the step (8);
(7) respectively taking 1 sound wave frequency with a target diffraction angle and an incident angle of a corresponding incident beam on each diffraction angle curve of the acousto-optic Dixon equation, and transferring to the step (8);
(8) the n incident beams are incident to the acousto-optic crystal at corresponding incident angles, and (n-i) sound waves with different frequencies are loaded on the acousto-optic crystal;
(9) the incident beam and the sound wave are subjected to abnormal Bragg diffraction to form a composite wave with a target diffraction angle.
The number of acoustic waves with different frequencies loaded by the acousto-optic crystal is reduced, so that the intermodulation phenomenon and the beam intensity modulation phenomenon of the acoustic waves are reduced, and the number of the acoustic waves in general research is less than or equal to 3; however, as the number of acoustic waves decreases, the upper limit of the number of incident beams corresponding to the combined wave decreases.
When the wavelengths of incident beams are different, sound waves with frequencies corresponding to the intersection points of diffraction angle curves of the acousto-optic Dixon equation are loaded in the acousto-optic crystal, so that the number of the sound waves can be reduced under the condition that the number of the incident beams is not changed;
in practical applications, reducing the intermodulation effect of the sound wave is also of great concern, and several methods for reducing the intermodulation of the sound wave are introduced below.
First, the center frequency of the acousto-optic crystal is located in a narrow bandwidth region, which is beneficial to reducing the acoustic wave intermodulation influence so as to design a corresponding acousto-optic crystal.
Secondly, under the condition that other conditions are not changed, the frequency interval of the acoustic wave loaded by the acoustic crystal is increased, and the reduction of the intermodulation influence of the acoustic wave is facilitated.
And thirdly, under the condition that other conditions are not changed, the length of the acousto-optic crystal transducer is reduced, and the acoustic wave intermodulation influence is favorably reduced. However, the length of the transducer must be such that the acousto-optic interaction enters the Bragg diffraction zone, i.e. the transducer length cannot be reduced indefinitely;
the laser beam combining method based on acousto-optic anomalous Bragg diffraction provided by the invention is described below by combining with an embodiment.
Example 1
As shown in fig. 2, embodiment 1 provides two incident light beams with the same wavelength (i.e., the number n of incident light beams is 2, and the wavelength m of incident light is 1) for performing acoustic beam combination;
selecting a target diffraction angle of 9.753 degrees, and obtaining 2 sound wave frequencies f with the same diffraction light angle according to the target diffraction angle of the resultant wave and 1 acousto-optic Dixon equation diffraction angle curve1，f2Respectively as follows: optimum incident angle theta of 70MHz, 93.27MHz and corresponding 2 incident beamsi1，θi2Respectively as follows: 6.784 °, 5.797 °; two incident beams are incident on an acousto-optic crystal loaded with sound waves of 70MHz and 93.27MHz at an angle of 6.784 degrees and 5.797 degrees to generate anomalous Bragg diffraction, so that a composite wave with a diffraction angle of 9.753 degrees is formed;
wherein the incident light wavelength lambda is 1064nm, the acousto-optic crystal is tellurium oxide, the polarization state is 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 crystal [110 ]]Angle of direction thetaa6.2911 DEG, and +1 st order diffraction light is adopted;
further, when the target diffraction angle was 9.753 °, 2 sound wave frequencies f having the same diffraction angle were selected1，f2Respectively become 60MHz, 113.5MHz, and the optimal incident angle theta corresponding to 2 incident light beamsi1，θi27.426 deg. and 5.222 deg. respectively.
Example 2
As shown in fig. 3, example 2 provides a case where two incident light beams with different incident light wavelengths (i.e., the number n of incident light beams is 2, and the incident light wavelength m is 2) are combined acoustically;
selecting a target diffraction angle of 10.06 degrees, collecting diffraction angles of 1 intersection point corresponding to a diffraction angle curve of a Dixon equation of sound and light, finding that the diffraction angles of the intersection points are different from the target diffraction angle, and selecting 2 sound wave frequencies f with the same diffraction angles1，f2Optimum incidence angles theta of 140MHz, 120MHz and corresponding 2 incident light beamsi1，θi27.223 degrees and 4.971 degrees are respectively formed, two incident beams are incident on the acousto-optic crystal loaded with 140MHz and 120MHz sound waves at the angles of 7.223 degrees and 4.971 degrees to generate abnormal Bragg diffraction, and a composite wave with the diffraction angle of 10.06 degrees is formed;
wherein the wavelength of light wave is lambda1，λ2532nm and 1064nm, the acousto-optic crystal is tellurium oxide, the polarization state is 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 crystal [110 ]]Angle of direction thetaaComprises the following steps: 6.2911 DEG, adopting +1 st order diffraction light;
further, if the selected target diffraction angle is 10.21 degrees, collecting diffraction angles at 1 intersection point of the acousto-optic dickson equation diffraction angle curve, finding that the diffraction angle of the intersection point is the same as the target incident angle, selecting the acoustic wave frequency f of the intersection point to be 129.8MHz, enabling two incident light beams to be incident to the acousto-optic crystal at 7.223 degrees and 4.971 degrees, loading the acoustic wave of the 129.8MHz on the acousto-optic crystal, and enabling the incident light wave and the acoustic wave to generate abnormal Bragg diffraction to form a composite wave with the changed target diffraction angle of 10.21 degrees.
Example 3
As shown in fig. 4, example 3 provides a case where three incident light beams with different wavelengths (i.e., the number n of incident light beams is 3, and the wavelength m of the incident light beams is 3) are combined acoustically;
the selected target diffraction angle is 10.06 degrees, the diffraction angles of 3 intersection points corresponding to the diffraction angle curve of the acousto-optic Dixon equation are collected, the diffraction angles of the intersection points are found to be different from the target diffraction angle, and 3 acoustic frequencies f with the same diffraction angles are selected1，f2And f3At 140MHz, 120MHz and 111.2MHz, and corresponding to the optimal incident angle theta of 2 incident light beamsi1，θi2And thetai3Respectively as follows: 7.223 degrees, 4.971 degrees and 7.406 degrees, 3 beams of incident light are incident to the acousto-optic crystal at the incident angles of 7.223 degrees, 4.971 degrees and 7.406 degrees, meanwhile, the acousto-optic crystal is loaded with the sound waves of the 3 frequencies (140MHz, 120MHz and 111.2MHz), and the incident light beams and the sound waves are subjected to abnormal Bragg diffraction to form a composite wave with a target diffraction angle;
wherein: wavelength of incident light λ1，λ2And λ3532nm, 1064nm and 632.8nm, the acousto-optic crystal is tellurium oxide, the polarization state is 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 crystal [110 ]]Angle of direction thetaaComprises the following steps: 6.2911 DEG, adopting +1 st order diffraction light;
further, if the selected target diffraction angle becomes 10.21 °, the diffraction angles at 3 intersection points of the acousto-optic dixon equation diffraction angle curve in a certain sound propagation direction are collected, the diffraction angle of one intersection point is found to be the same as the target incidence angle, and 1 intersection point sound wave frequency f which enables the diffraction angle to be the same is selected1The frequency of the rest 1 sound wave f is selected from the diffraction curves of the rest acousto-optic Dixon equation at 129.8MHz2Is 103.8MHz, and corresponds to an optimal incident angle θ of 3 incident beamsi1，θi2And thetai37.577 °, 4.702 ° and 7.746 °, respectively; 3 incident beams are incident to the acousto-optic crystal at the incident angles of 7.577 degrees, 4.702 degrees and 7.746 degrees, meanwhile, the acousto-optic crystal loads the sound waves with the 2 frequencies (129.8MHz and 103.8MHz), and the incident beams and the sound waves are subjected to abnormal Bragg diffraction to form a composite wave with the diffraction angle of 10.21 degrees.
In summary, according to the target diffraction angle, the number of the incident light wavelengths and the number of the incident light beams, the frequency of the acoustic wave and the incident angle of the incident light beams are determined by using the acousto-optic dixon equation diffraction curve; the acoustic wave loaded on the acousto-optic crystal is determined according to the calculated acoustic wave frequency, the included angle between the incident beam and the acousto-optic crystal is determined according to the incident angle, the acoustic wave and the incident beam are subjected to abnormal Bragg diffraction, and the resultant wave of the target diffraction angle can be obtained.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A laser beam combining method based on acousto-optic anomalous Bragg diffraction is characterized by comprising the following steps:
determining a composite wave intersection point with a target diffraction angle according to acousto-optic Dixon equation diffraction curves corresponding to incident light wavelengths;
step (2) acquiring the frequency of the sound wave and the incident angle of the incident light beam on the diffraction angle curve of the acousto-optic Dixon equation according to the number of the incident light wavelengths, the number of the incident light beams with the same wavelength and the resultant intersection point with the target diffraction angle;
loading sound waves on the acousto-optic crystal, and enabling incident beams to be incident into the acousto-optic crystal at an incident angle;
the incident beam and the sound wave are subjected to anomalous Bragg diffraction to form a composite wave with a target diffraction angle;
the target diffraction angle is larger than the maximum extreme value diffraction angle of the acousto-optic Dixon equation diffraction curve; the acousto-optic Dixon equation diffraction curves are all abnormal Bragg diffraction of +1 level or all abnormal Bragg diffraction of-1 level; the incident beams all have the o light polarization state of the acousto-optic crystal.
2. The method according to claim 1, wherein in step (2), if the number of wavelengths of the incident light is 1 and the number of incident light beams is 2, the acoustic frequency with the target diffraction angle and the incident angle of the corresponding incident light beam are obtained on the dixon equation diffraction angle curve of the acousto-optic.
3. The method according to claim 1, wherein in step (2), if the number of wavelengths of the incident light is greater than 1 and equal to the number of incident light beams, the acoustic frequency with the target diffraction angle and the incident angle of the corresponding incident light beam are obtained on each dixon equation diffraction angle curve of the acousto-optic.
4. The laser beam combining method according to claim 1, wherein if the number of the incident light wavelengths is greater than 1, the number of the incident light wavelengths is not equal to the number of the incident light beams, the number of the incident light beams having the same wavelength is less than or equal to 2, and there is a combined wave intersection point having a target diffraction angle, the step (2) specifically includes:
(2.1) randomly selecting acoustic frequency corresponding to i combined wave intersection points and incident angles of 2i incident beams from the combined wave intersection points with the target diffraction angle according to the target diffraction angle and the diffraction angle curve of the Dixon equation of the acousto-optic;
and (2.2) respectively taking 1 sound wave frequency and the incident angle of the corresponding incident beam on the diffraction angle curve of the acousto-optic Dixon equation corresponding to the wavelength of the residual incident beam, wherein i is more than or equal to 1.
5. The method according to claim 1, wherein if the number of the incident light wavelengths is greater than 1, the number of the incident light wavelengths is not equal to the number of the incident light beams, the number of the incident light beams having the same wavelength is less than or equal to 2, and there is no junction point of the incident light beams having the target diffraction angle, 1 sound wave frequency having the target diffraction angle and the incident angle of the corresponding incident light beam are respectively taken on the diffraction angle curve of the acousto-optic dixon equation corresponding to the wavelength of each incident light beam.
6. The method of any of claims 1 to 5, wherein the incident angle of the incident beam is a Bragg angle.
7. The laser beam combining method according to any of claims 1 to 5, wherein the acoustic wave with anomalous Bragg diffraction is a shear wave.
8. The method of claim 1, wherein the plurality of incident beams having the same wavelength are combined in a cascade manner.
9. The method according to claim 4, wherein if the number of the incident light wavelengths is greater than 1, the number of the incident light wavelengths is not equal to the number of the incident light beams, the number of the incident light beams having the same wavelength is less than or equal to 2, and when there is a complex intersection point having a target diffraction angle, the acoustic frequency and the incident angle of the incident light beam corresponding to all the complex intersection points are selected.
10. The method of claim 1, wherein the diffraction efficiency of the incident beam and the acoustic wave with bragg diffraction anomalies is adjusted by the power of the acoustic wave with different frequencies, so as to control the energy ratio of the combined beam.
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|---|---|---|---|---|
| BE1007876A4 (en) * | 1993-12-17 | 1995-11-07 | Philips Electronics Nv | Radiation source unit for generating a bundle with two polarization directions and two rates. |
| US6154307A (en) * | 1998-09-18 | 2000-11-28 | United Technologies Corporation | Method and apparatus to diffract multiple beams |
| US7375819B2 (en) * | 2005-11-01 | 2008-05-20 | Agilent Technologies, Inc. | System and method for generating beams of light using an anisotropic acousto-optic modulator |
| CN102621695A (en) * | 2012-03-22 | 2012-08-01 | 华中科技大学 | Pulse laser beam combining method |
| DE102013227105A1 (en) * | 2013-09-03 | 2015-03-05 | Leica Microsystems Cms Gmbh | Microscope and acousto-optical beam combiner for a microscope |
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2019
- 2019-10-28 CN CN201911028370.5A patent/CN110764286B/en active Active
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