CN111473953A - Fiber laser mode decomposition method based on phase recovery and implementation device thereof - Google Patents
Fiber laser mode decomposition method based on phase recovery and implementation device thereof Download PDFInfo
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Abstract
The invention discloses a fiber laser mode decomposition method based on phase recovery and a realization device thereof, wherein the method comprises four steps, namely, step 1: calibrating the mode decomposition device by using single-mode laser, and further adjusting the relative position of an optical element in the mode decomposition device; step 2: replacing a fiber laser in the mode decomposition device to realize few-mode laser output, and collecting few-mode light spots required by mode decomposition through the mode decomposition device; and step 3: recovering the phase of the multi-mode light spot by using a GS iterative algorithm of the multi-position light spot to obtain the complex amplitude of the multi-mode light spot; and 4, step 4: and carrying out mode decomposition on the complex amplitude by adopting a correlation projection algorithm, and optimizing by using a mode decomposition result as an initial value of a random parallel gradient descent algorithm. The invention solves the problem that the traditional random parallel gradient descent algorithm is easy to fall into local optimum due to sensitivity to initial values, and improves the number of modes which can be decomposed while maintaining the precision.
Description
Technical Field
The invention relates to the field of laser measurement, in particular to a fiber laser mode decomposition method based on phase recovery and an implementation device thereof.
Background
The laser technology is one of four important inventions in the twentieth century and is famous for atomic energy, semiconductors and computers. Laser technology based on lasers has been rapidly developed for more than forty years, and the laser technology has been widely applied to various fields such as industrial production, communication, information processing, medical health, military, cultural education, scientific research and the like, obtains good economic and social benefits, and plays an increasingly important role in national economy and social development. The fiber laser has the advantages of no optical lens in the resonant cavity, no adjustment, no maintenance and high stability, and is widely applied to high-power lasers. However, mode competition, mode coupling, and mode-related processes such as MI in the few-mode fiber laser at high power may cause deterioration of the output environment. Therefore, it is necessary to analyze the above process in depth from the mode point of view, which relies on the emerging mode decomposition technique in the fiber laser field to obtain the mode characteristics in the output beam of the fiber laser, including the content and phase of each eigenmode.
An anti et al, in L incidence to the module in the methods in the field of feedback with the possibility of interference in terms of aberration, studies the mode decomposition process of obtaining complex amplitude based on wavefront detection in a document of composite measurement of fiber optics system, which is to calculate the complex amplitude of the single-mode complex amplitude and the complex amplitude correlation operation of each mode, and calculates the aberration decomposition result, so the aberration decomposition result has a deviation.
Disclosure of Invention
The invention aims to provide a fiber laser mode decomposition method based on phase recovery and an implementation device thereof, which are not sensitive to the influence of aberration, and solve the problem that the traditional numerical analysis method (SPGD) is easy to fall into local optimum due to sensitivity to an initial value, so that the mode decomposition number is increased from the original three modes to more than ten modes at present.
The solution for realizing the invention is as follows: a fiber laser mode decomposition method based on phase recovery comprises the following steps:
and 4, carrying out mode decomposition on the complex amplitude by adopting a correlation projection algorithm, and optimizing by using a mode decomposition result as an initial value of a random parallel gradient descent algorithm.
With reference to fig. 4, an implementation apparatus of a fiber laser mode decomposition method based on phase recovery implements measurement and collection by a mode decomposition apparatus, the mode decomposition apparatus includes a fiber laser, an optical amplification system, a power attenuation and light spot collection system and a computer, the fiber laser, an optical fiber to be measured, the optical amplification system, the power attenuation and light spot collection system are sequentially disposed along a light path, and the power attenuation and light spot collection system is connected to the computer.
Furthermore, the optical magnification system adopts a 4F confocal system, and a first lens, a first reflector, a second reflector and a second lens are arranged along the optical path in sequence.
Furthermore, the laser attenuation and collection system comprises a laser attenuation system, a third reflector, a fourth reflector and a detector which are sequentially arranged along the light path.
Compared with the prior art, the invention has the remarkable advantages that:
(1) through the calibration process of the fundamental mode light, the interference of aberration on the mode decomposition result is avoided, and the precision of the mode decomposition result is greatly improved.
(2) Through the use of an iterative algorithm, only spot intensity information is required to perform complex amplitude based mode decomposition. The method solves the problem of complex phase measurement, combines two large mode decomposition methods of a phase measurement method and a numerical analysis method in mode decomposition, and improves the speed and the precision of the mode decomposition.
(3) And the mode decomposition step is to combine the correlation projection algorithm and the random parallel gradient descent algorithm. Firstly, a mode decomposition result is obtained by using a related projection algorithm, the mode decomposition result is used as an initial value, then the optimization is carried out by using a random parallel gradient lower solution algorithm, and finally, an accurate mode decomposition coefficient and the phase of each mode relative to a basic mode are obtained. The method solves the problem that the related projection algorithm is sensitive to aberration, and also solves the problem that the random parallel gradient descent algorithm is easy to fall into local optimum, which directly causes the number of modes which can be decomposed by the random parallel gradient descent algorithm to be increased from three to tens of modes. And the calculation speed is indirectly improved due to the reduction of the calculation amount.
Drawings
FIG. 1 is a flow chart of the method steps of the fiber laser mode decomposition method based on phase recovery and the implementation device thereof.
Fig. 2 is a flow chart of 3 position iteration algorithms of the fiber laser mode decomposition method based on phase recovery and the implementation device thereof.
FIG. 3 is a flow chart of a mode decomposition algorithm of the fiber laser mode decomposition method based on phase recovery and the implementation device thereof.
FIG. 4 is a device light path diagram of the fiber laser mode decomposition method based on phase recovery and the implementation device thereof.
Fig. 5 is a graph showing the phase recovery results of the embodiment of the present invention, i.e. the intensity before and after the iterative recovery of the light spots at three positions (210, 300, 390) and the difference between the three positions.
Fig. 6 is a graph of the phase recovery results for three positions (210, 300, 390) in an example of the present invention.
FIG. 7 is a graph of the mode decomposition results, i.e., the phase of each mode fraction and each high order mode versus L P01 mode, for an example of the present invention.
FIG. 8 is a graph showing the intensity and phase distribution of the mode decomposition result, i.e., the reconstructed intensity of the mode decomposition result, according to the embodiment of the present invention.
Detailed Description
With reference to fig. 1, a method for decomposing a fiber laser mode based on phase recovery includes the following steps:
the fiber laser mode decomposition method based on phase recovery realizes measurement and collection through a mode decomposition device, the mode decomposition device comprises a fiber laser 1, an optical amplification system 3, a power attenuation and light spot collection system 8 and a computer 13, the fiber laser 1, an optical fiber 2 to be detected, the optical amplification system 3 and the power attenuation and light spot collection system 8 are sequentially arranged along a light path, and the power attenuation and light spot collection system 8 is connected with the computer 13.
The optical amplification system 3 adopts a 4F confocal system and sequentially comprises a first lens 4, a first reflector 5, a second reflector 6 and a second lens 7 along an optical path; the first reflector 5 is arranged on the transmission light path of the first lens 4, the second reflector 6 is arranged on the reflection light path of the first reflector 5, and the second lens 7 is arranged on the reflection light path of the second reflector 6.
The laser attenuation and collection system 8 comprises a laser attenuation system 9, a third reflector 10, a fourth reflector 11 and a detector 12 which are sequentially arranged along a light path. The third mirror 10 is placed in the transmission direction of the laser attenuation system 9, the fourth mirror 11 is placed in the reflection direction of the third mirror 10, and the detector 12 is placed in the reflection direction of the fourth mirror 11, wherein the third mirror 10 and the fourth mirror 11 can move back and forth along the optical axis. The detector is connected to a computer 13, and the computer 13 is used for implementing the phase recovery algorithm and the pattern decomposition algorithm in the method. The above-described devices except the computer 13 are all placed on an optical platform.
Calculating the fiber 2 to be measured at L P01The cut-off wavelength of the mode is selected, then the fiber laser 1 with the center wavelength higher than the cut-off wavelength is selected, and the laser emitted by the fiber laser 1 only emits linear polarization L P after passing through the fiber 2 to be detected01Laser light of the mode, the linear polarization L P01The laser of the mode is sent into the optical amplifying system 3 for amplification, the amplified laser enters the laser attenuation and acquisition system 8 again to realize the attenuation and acquisition of light spots, and the acquired light spot intensity distribution is sent into the computer 13 for analysis and calculation;
if the acquired spot intensity distribution does not comply with L P01Modulo, indicating a deviation in the relative positions of the internal optical elements of the optical magnification system 3, the spatial three-dimensional positions of the first lens 4 and the second lens 7 are adjusted such that the spot intensity distribution read by the detector 12 is analyzed to comply with the norm L P01The mode laser intensity distribution, i.e. the beam waist positions in the x and y directions are the same, the beam waist radii are the same, and the beam quality factor M2Approaching to 1; and (5) transferring to the step 2.
the fiber laser 1 is replaced, the wavelength of the replaced fiber laser 1 is required to be lower than the cut-off wavelengths of a plurality of modes, so that the few-mode laser comes out of the fiber 2 to be detected, the light spot intensity graph of the few-mode laser can be obtained by using a detector 12 after being transmitted by an optical amplification system 3, and the third reflector 10 and the fourth reflector 11 can move along the optical axis, so that the light spot graph of each point on the optical axis is collected by synchronously moving the third reflector 10 and the fourth reflector 11, and the step 3 is carried out.
And 3, recovering the phase of the multi-mode light spot by using a GS iterative algorithm of the multi-position light spot to obtain the complex amplitude of the multi-mode light spot.
The GS iterative algorithm is reversible with the light field transmission, iterating repeatedly between spot patterns at different positions of the optical axis, and substituting certain constraints at each iteration. Light spots at 3 positions are utilized, namely the 3 positions are iterated pairwise in sequence, and phase information is updated through continuous positive and negative light field transmission until the preset precision or iteration times are reached. And finally, obtaining the complex amplitude information of each position for the pattern decomposition algorithm.
The GS algorithm flow from location 1 to location 2 is shown in fig. 2:
step 3-1, knowing the spot intensity information I of 2 positionsz1，Iz2Setting the spot phase information phi of position 1z1；
Step 3-2, the intensity I of the position 1z1And the set phase phiz1Obtaining the complex amplitude E of position 1z1；
Step 3-3, adding Ez1Fourier transform is carried out to obtain a complex amplitude E 'at a position 2'z2；
Step 3-4, E'z2Is not changed, the amplitude is changed into the detected image surface amplitude
The complex amplitude E of position 2 is obtainedz2。
In order to make the phase recovery accurate and fast, we use the GS iterative algorithm of 3 positions (knowing 3 positions and the spot intensity information of the position, three positions are in turn position 1, position 2, and position 3 equally spaced along the optical axis):
step a, setting position1 initial phase value phi of light spotz1From spot intensity information I at position 1 and position 2z1，Iz2The complex amplitude E at position 2 is obtained by the GS algorithmz2；
Step b, light spot intensity information I of position 2 and position 3z2、Iz3And complex amplitude E of position 2z2Then, the complex amplitude E of the position 3 is obtained by the GS algorithmz3；
Step c, light spot intensity information I of position 3 and position 2z2、Iz3And complex amplitude E of position 3z3The complex amplitude E 'of position 2 is obtained by GS algorithm (Fourier transform is inverse Fourier transform)'z2；
Step d, light spot intensity information I of position 2 and position 1z1、Iz2And complex amplitude E 'of position 2'z2The complex amplitude E 'of position 1 is obtained by GS algorithm (Fourier transform is inverse Fourier transform)'z1；
Step E, converting the complex amplitude E 'of the position 1'z1Generating a reconstructed light intensity distribution I 'after transmission to position 2'z2And obtaining an evaluation function J;
and f, judging whether the J meets the precision requirement, if not, re-performing the steps a to e until a result meeting the precision is obtained.
And 4, carrying out mode decomposition on the complex amplitude by adopting a correlation projection algorithm, and optimizing by taking a mode decomposition result as an initial value of a random parallel gradient descent algorithm, wherein the method specifically comprises the following two parts:
a first part: the related projection algorithm is to perform complex amplitude correlation operation on the complex amplitude of the light spot obtained by calculation in the step 3 and ideal single-mode orthogonal components of each mode to respectively obtain decomposition results of each group of modes, and the formula is as follows:
wherein c isjIs a projection coefficient, EmesFor complex amplitude of the spot to be measured, ELPjIdeal single-mode orthogonal components for each mode; finally calculated cjThe ratio of each mode and its phase information are obtained, and (x, y) represents coordinates.
A second part: and substituting the mode decomposition result as an initial value into a random parallel gradient descent algorithm for optimization to obtain an accurate mode decomposition result, wherein a performance evaluation function J in the algorithm flow is set as a cross-correlation function between measured and reconstructed light intensity distribution. The concrete form is as follows:
wherein
In the formula
Mean values of the light intensity distribution are indicated, re and me represent the reconstructed and actually measured light intensity distribution, respectively, and r and phi represent coordinates. J obtains a maximum value of 1 in the case where the reconstructed light intensity distribution and the measured light intensity distribution are completely identical.
J is set to 0.99 in the GS phase recovery algorithm for 3 positions in step 3 and to 0.999 in the pattern decomposition algorithm in step 4.
The basic idea of the random parallel gradient descent algorithm is to apply random perturbation which is not statistically related to all variables of a performance evaluation function at the same time, then continuously update all variables according to the magnitude of the perturbation and the variation of the performance evaluation function, and finally obtain a mode coefficient corresponding to the performance evaluation function and each mode phase, namely a mode decomposition result, when the performance evaluation function reaches a preset precision or iteration times.
The specific program flow of the pattern decomposition algorithm in step 4 is shown in fig. 3:
wherein the relevant projection method mode decomposition step comprises the following steps:
step 4-1, extracting the light spot complex amplitude information E obtained in the step 3mes；
Step 4-2, correcting the complex amplitude of the light spot with the standard of each modeThe cross component is subjected to correlation calculation to obtain a projection coefficient Cjk；
Step 4-3, calculating the ratio rho of each mode according to the projection coefficientiAnd corresponding phase information thetai；
Step 4-4, switching to a random parallel gradient descent algorithm for calculation, and setting an initial variable rhoi，θi(i.e., correlation projection mode decomposition results);
step 4-5, generating and storing random perturbation rhoi，θi；
Step 4-6, superposing the random perturbation and the positive and negative variables rhoi±＝ρi±ρi，θi±＝θi±θi；
Step 4-7, generating a reconstructed light intensity distribution Ire±；
Step 4-8, obtaining a performance evaluation function J±；
Step 4-9, updating variable rhoi＝ρi+γ1(J+-J-)ρi，θi＝θi+γ2(J+-J-)θi；
Step 4-10, generating a reconstructed light intensity distribution IreAnd obtaining an evaluation function J;
and 4-11, judging whether the J value of the evaluation function is greater than the set precision, and returning to the step 4-5 for calculation if the J value of the evaluation function is not greater than the set precision.
The mode decomposition method can not only rapidly carry out mode decomposition on the detected light spot, but also keep the accuracy of the mode decomposition result.
Example 1
The experimental optical path is shown in fig. 1, and a 4F confocal system is composed of a first lens 4, a first reflector 5, a second reflector 6, and a second lens 7, wherein the first lens 4 is a microscope objective lens with a focal length of 8.5mm, and the second lens 7 is an objective lens with a focal length of 300 mm. The optical fiber 2 to be detected is a 20\400mm optical fiber, and the detector 12 is a light intensity detector, namely a CCD camera.
Coupling the laser of the fiber laser 1 with the wavelength of 1066nm into the fiber 2 to be measured, wherein the fiber port emits the laser intensityThe distribution should be L P01The laser is emitted and passes through a first lens 4, wherein the output port of the optical fiber 2 to be detected is on the object space focal plane of the first lens 4, the laser is transmitted through the first lens 4, reflected by a first reflector 5 and a second reflector 6, attenuated by a power attenuation device 9, reflected by a third reflector 10 and a reflector 11, and received by a detector 12, and the laser collected by the detector is L P after three-dimensional adjustment of the first lens 401Mode distribution, and calculating the beam quality factor M of the laser by multi-position acquisition2Approximately 1, and the waist positions are the same, the device calibration is complete (by Spricion M)2-200s beam quality analyzer).
Keeping the experimental light path unchanged, replacing the fiber laser 1 with a laser with the wavelength of 633nm, wherein the laser emitted from the fiber 2 to be tested is a few-mode laser, and 12 modes (L P) can be excited by calculating that 633nm is coupled into 20/400 mu m fiber01、LP02、LP11e、LP11o、LP12e、LP12o、LP21e、LP21o、LP31e、LP31o、LP41eAnd L P41o) After passing through the optical path shown in fig. 1, the few-mode laser enters the detector 12, so that the focal point of the few-mode laser is on the image focal plane of the objective lens, and the positions of the third reflector 10 and the fourth reflector 11 on the guide rail are changed to acquire a spot intensity map at each position.
Light spots at 3 point positions in the result are obtained, the light spots at 210mm, 300mm and 390mm positions are obtained in the experiment, the light spot intensity data at the three positions are substituted into an iterative algorithm to solve intensity and phase information of each position, the obtained light intensity recovery result and difference of each position are shown in fig. 5, and the phase information of each position is shown in fig. 6.
Extracting intensity and phase information of light spots at 300mm, performing complex amplitude correlation operation with ideal single-mode orthogonal components of each mode to obtain a group of mode decomposition results, using the mode decomposition results as initial values, and optimizing by adopting a random parallel gradient descent algorithm to finally obtain accurate mode decomposition results, as shown in fig. 7, namely, the mode occupation ratio and the mode heightOrder mode opposition L P01The phase of the mode, wherein the reconstructed light intensity of the mode decomposition result and the phase distribution thereof are shown in fig. 8.
Claims (10)
1. A fiber laser mode decomposition method based on phase recovery is characterized by comprising the following steps:
step 1, calibrating a mode decomposition device by using a single-mode laser, further adjusting the relative position of an optical element in the mode decomposition device, and turning to step 2;
step 2, replacing the optical fiber laser in the mode decomposition device to realize few-mode laser output, collecting few-mode light spots required by mode decomposition through the mode decomposition device, and turning to step 3;
step 3, recovering the phase of the multi-mode light spot by using a GS iterative algorithm of the multi-position light spot to obtain the complex amplitude of the multi-mode light spot, and turning to step 4;
and 4, carrying out mode decomposition on the complex amplitude by adopting a correlation projection algorithm, and optimizing by using a mode decomposition result as an initial value of a random parallel gradient descent algorithm.
2. The phase recovery-based fiber laser mode decomposition method according to claim 1, wherein: in the step 1, the mode decomposition device comprises a fiber laser (1), an optical amplification system (3), a power attenuation and light spot acquisition system (8) and a computer (13), wherein the fiber laser (1), an optical fiber (2) to be detected, the optical amplification system (3) and the power attenuation and light spot acquisition system (8) are sequentially arranged along a light path, and the power attenuation and light spot acquisition system (8) is connected with the computer (13);
calculating the fiber (2) to be measured at L P01The cut-off wavelength of the mode is that the fiber laser (1) with the center wavelength higher than the cut-off wavelength is selected, and the laser emitted by the fiber laser (1) only emits linear polarization L P after passing through the fiber (2) to be tested01Laser light of the mode, the linear polarization L P01The laser of the mode is sent into an optical amplifying system (3) for amplification, the amplified laser enters a laser attenuation and acquisition system (8) again to realize the attenuation and acquisition of light spots, and the acquired light spot intensity distribution is sent into a computer (13) for analysis and countingCalculating;
if the acquired spot intensity distribution does not comply with L P01The mode indicates that the relative position of the internal optical elements of the optical amplification system (3) has deviation, and the spatial three-dimensional position of the optical components in the optical amplification system (3) is adjusted, so that the intensity distribution of the light spot read by the laser attenuation and collection system (8) is analyzed and obeyed standard L P01The mode laser intensity distribution, namely the beam waist positions in the x and y directions are the same, the beam waist radii are the same, and the beam quality factor M2Approaching 1.
3. The phase recovery-based fiber laser mode decomposition method according to claim 1, wherein: in the step 2, the fiber laser (1) is replaced, the wavelength of the replaced fiber laser (1) is required to be lower than cut-off wavelengths of a plurality of modes, so that the few-mode laser comes out of the fiber (2) to be detected, after the few-mode laser is transmitted by the optical amplification system (3), a light spot intensity diagram of the few-mode laser can be obtained by the power attenuation and light spot acquisition system (8), and because a reflector in the power attenuation and light spot acquisition system (8) can move along the optical axis, a light spot diagram of each point on the optical axis is acquired by synchronously moving the reflector in the power attenuation and light spot acquisition system (8).
4. The phase recovery-based fiber laser mode decomposition method according to claim 1, wherein: in step 3, the GS iterative algorithm of the multi-position light spots is reversible by utilizing light field transmission, repeated iteration is carried out between light spot images at different positions of an optical axis, and a certain constraint is substituted in each iteration.
5. The method of claim 1, wherein in step 3, the GS iterative algorithm of the multi-position light spot is as follows:
and (3) utilizing the light spots at 3 positions with different optical axes, continuously carrying out positive and negative light field transmission, updating phase information until reaching preset precision or iteration times, thereby recovering the phases of the few-mode light spots and obtaining the complex amplitude of the multi-mode light spot.
6. The fiber laser mode decomposition method based on phase recovery as claimed in claim 1, wherein in step 4, the correlation projection algorithm is a complex amplitude correlation operation of the complex amplitude of the light spot and the ideal single-mode orthogonal component of each mode, and the formula is as follows:
wherein c isjIs a projection coefficient, EmesFor complex amplitude of the spot to be measured, ELPjIdeal single-mode orthogonal components for each mode; finally calculated cjThe ratio of each mode and its phase information are obtained, and (x, y) represents coordinates.
7. The phase recovery-based fiber laser mode decomposition method according to claim 1, wherein: in step 4, the random parallel gradient descent algorithm has the basic idea that all variables of the performance evaluation function are simultaneously subjected to random perturbation which is not statistically related, all variables are continuously updated according to the magnitude of the perturbation and the variation of the performance evaluation function, and the mode coefficients and the mode phases corresponding to the performance evaluation function are finally obtained as mode decomposition results when the performance evaluation function reaches the preset precision or iteration times.
8. An implementation device of a fiber laser mode decomposition method based on phase recovery is characterized in that: the fiber laser mode decomposition method based on phase recovery realizes measurement and collection through a mode decomposition device, the mode decomposition device comprises a fiber laser (1), an optical amplification system (3), a power attenuation and light spot collection system (8) and a computer (13), the fiber laser (1), an optical fiber (2) to be detected, the optical amplification system (3), the power attenuation and light spot collection system (8) are sequentially arranged along a light path, and the power attenuation and light spot collection system (8) is connected with the computer (13).
9. The device for realizing the fiber laser mode decomposition method based on the phase recovery as claimed in claim 8, wherein: the optical magnification system (3) adopts a 4F confocal system and sequentially comprises a first lens (4), a first reflector (5), a second reflector (6) and a second lens (7) along an optical path; the first reflector (5) is arranged on the transmission light path of the first lens (4), the second reflector (6) is arranged on the reflection light path of the first reflector (5), and the second lens (7) is arranged on the reflection light path of the second reflector (6).
10. The device for realizing the fiber laser mode decomposition method based on the phase recovery as claimed in claim 8, wherein: the laser attenuation and collection system (8) comprises a laser attenuation system (9), a third reflector (10), a fourth reflector (11) and a detector (12) which are sequentially arranged along a light path; the third reflector (10) is arranged in the transmission direction of the laser attenuation system (9), the fourth reflector (11) is arranged in the reflection direction of the third reflector (10), the detector (12) is arranged in the reflection direction of the fourth reflector (11), wherein the third reflector (10) and the fourth reflector (11) can move back and forth along the optical axis, the detector (12) is connected with a computer (13), and the computer (13) is used for realizing a phase recovery algorithm and a mode decomposition algorithm in the method.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112003114A (en) * | 2020-08-04 | 2020-11-27 | 中国科学院上海光学精密机械研究所 | Mode control system and control method of fiber laser with multimode fiber output |
| CN112816181A (en) * | 2020-12-29 | 2021-05-18 | 中国人民解放军国防科技大学 | High-speed real-time optical fiber laser mode detection method and detection device thereof |
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Cited By (9)
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|---|---|---|---|---|
| CN112003114A (en) * | 2020-08-04 | 2020-11-27 | 中国科学院上海光学精密机械研究所 | Mode control system and control method of fiber laser with multimode fiber output |
| CN112816181A (en) * | 2020-12-29 | 2021-05-18 | 中国人民解放军国防科技大学 | High-speed real-time optical fiber laser mode detection method and detection device thereof |
| CN112816181B (en) * | 2020-12-29 | 2023-03-14 | 中国人民解放军国防科技大学 | High-speed real-time optical fiber laser mode detection method and detection device thereof |
| CN113219482A (en) * | 2021-04-08 | 2021-08-06 | 三明学院 | Laser monitoring device and monitoring method capable of improving energy utilization rate |
| CN113219482B (en) * | 2021-04-08 | 2024-05-03 | 三明学院 | Laser monitoring device capable of improving energy utilization rate and monitoring method |
| CN113376448A (en) * | 2021-04-29 | 2021-09-10 | 北京邮电大学 | Method and device for quiet zone phase recovery in compact range test |
| CN113376448B (en) * | 2021-04-29 | 2023-02-28 | 北京邮电大学 | Method and device for quiet zone phase recovery in compact range test |
| CN114448506A (en) * | 2021-12-20 | 2022-05-06 | 中国人民解放军国防科技大学 | High-speed optical fiber laser mode analysis system suitable for multiple high-order mode measurement |
| CN114448506B (en) * | 2021-12-20 | 2023-09-22 | 中国人民解放军国防科技大学 | High-speed fiber laser mode analysis system suitable for measuring multiple high-order modes |
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