Unstable cavity laser with compensation function

Abstract

The invention discloses an unstable cavity laser with a compensation function. The unstable cavity laser comprises a cavity mirror, a gain module and a pumping source, the system also comprises a distortion compensation system, and the distortion compensation system comprises a real-time online compensation system and a high-order distortion compensation system. The real-time online compensation system comprises two pieces of 633nm semi-transparent and semi-reflecting mirrors, a 633nm light source, a deformable mirror I, a deformable mirror II, a far and near field tester, a power tester and a control system; the high-order distortion compensation system comprises a lens system and a diaphragm. Two 633nm semi-transparent and semi-reflective mirrors (enabling 633nm probe light to be guided into a laser), a deformable mirror I and a deformable mirror II are added in a cavity, and real-time online compensation of wavefront distortion is realized through a far field, a near field and a control system; and meanwhile, a lens system and a diaphragm are added in the cavity to compensate for high-order distortion, so that the problems of wavefront distortion of the laser and poor quality of an output laser beam caused by heat production of a medium in the gain module are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of solid laser light sources, in particular to an unstable cavity laser with a compensation function. Background Art

[0002] High-power solid-state laser light sources have urgent application needs in the fields of laser processing and national security. As the power increases, the thermal effect shows a nonlinear growth characteristic. The uncontrollable laser beam quality caused by the mutual coupling of solid medium heat generation, fluid cooling, and laser transmission has become a bottleneck problem that limits the application of high-power solid-state lasers. Specifically, the medium in the gain module generates heat, which causes the laser wavefront to be distorted and the output laser beam quality to deteriorate.

[0003] Therefore, an unstable cavity laser with compensation function is proposed. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides an unstable cavity laser with a compensation function to solve the problem that the medium in the gain module generates heat, causing the laser wavefront to be distorted and the output laser beam quality to deteriorate.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention proposes an unstable cavity laser with compensation function, which is divided into two forms: positive branch virtual confocal unstable cavity and negative branch real confocal unstable cavity, including cavity mirror, gain module and pump source; and also includes distortion compensation system,

[0007] The distortion compensation system includes a real-time online compensation system and a high-order distortion compensation system;

[0008] The real-time online compensation system includes two 633nm semi-transparent and semi-reflective mirrors, a 633nm light source, a deformable mirror 1, a deformable mirror 2, a far-field and near-field tester, a power tester, and a control system;

[0009] The high-order distortion compensation system includes a lens system and an aperture.

[0010] Preferably, the cavity mirrors of the positive-branch virtual confocal unstable cavity include concave reflection mirrors, scraper mirrors, and convex reflection mirrors.

[0011] Preferably, the cavity mirrors of the negatively supported real confocal unstable cavity include concave reflections, scraper mirrors, and concave reflection mirrors.

[0012] Preferably, the gain module is equipped with a Nd:YAG laser gain crystal and a cooler.

[0013] Preferably, the far-field and near-field tests have two sets, one set for real-time online compensation system testing, and the other set for output testing of unstable cavity lasers.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention realizes real-time online compensation of wavefront distortion by adding two 633nm semi-transparent and semi-reflective mirrors in the cavity (so that the 633nm detection light is introduced into the laser), deformable mirror 1, deformable mirror 2, and far field, near field and control system; at the same time, a lens system and an aperture are added in the cavity to realize compensation of high-order distortion, effectively solving the problem of laser wavefront distortion and deterioration of output laser beam quality caused by heat generation of the medium in the gain module. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the positive branch virtual confocal unstable cavity diagram in the present invention;

[0017] Figure 2 This is a negative support real confocal unstable cavity diagram in the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The present invention provides an unstable cavity laser with compensation function, comprising a cavity mirror, a gain module 7 and a pump source 8;

[0020] Also includes distortion compensation system,

[0021] The distortion compensation system includes a real-time online compensation system and a high-order distortion compensation system;

[0022] The real-time online compensation system includes two 633nm semi-transparent and semi-reflective mirrors 13, a 633nm light source 12, a deformable mirror 1 2, a deformable mirror 2 3, a far-field and near-field test 9, a power tester 11, and a control system;

[0023] The high-order distortion compensation system includes a lens system and an aperture, and the high-order distortion compensation system realizes compensation for high-order distortion;

[0024] The direction of the beam propagation is as follows: Figure 1-2 shown.

[0025] The wavefront distortion is suppressed and compensated in the strongly loaded laser positive branch virtual confocal unstable cavity and the negative branch real confocal unstable cavity. A far-field filter aperture is set in the cavity. The laser passes through the high-order filter structure many times during the oscillation in the cavity to achieve high-order suppression. At the same time, the 633nm detection light is introduced into the cavity through the semi-transparent and semi-reflective mirror 13 to perform round-trip detection of the cavity aberration. The obtained cavity wavefront information is used as a reference for active compensation of medium and low-order aberrations. This is used as feedback and an optimized compensation strategy is adopted to drive the deformable mirror 2 and the deformable mirror 3 to achieve compensation for medium and low-order aberrations.

[0026] Embodiment 1

[0027] For the positive-branch virtual confocal unstable cavity, the cavity mirror also includes two 633nm semi-transparent and semi-reflective mirrors 13, a 633nm light source 12, a far-field and near-field tester 9, a power tester 11, and a control system to achieve real-time online compensation of wavefront distortion, specifically: a laser gain module (GM) 7 is used to generate laser gain, and the module is equipped with a Nd:YAG laser gain crystal and a cooler, and an 808nm diode laser array (LDS) is used to perform double-end large-surface pumping on the gain module to ensure uniform heat generation on the surface of the laser crystal.

[0028] A lens system (4f imaging system) and an aperture are added to the cavity to compensate for high-order distortion. Figure 1 As shown, in the positive-branch virtual confocal unstable cavity, since there is no focusing in the cavity, it is necessary to insert a 4f imaging system in the parallel beam segment.

[0029] Embodiment 2

[0030] For the negative branch virtual confocal unstable cavity, the real-time online compensation of wavefront distortion is consistent with that of the first embodiment, but the compensation of high-order distortion is different from that of the first embodiment, such as Figure 2 As shown, there is a natural laser focus point in the negative-branch real confocal unstable cavity, so there is no need to insert a 4f imaging system and only need to place the aperture at the focus.

[0031] The technical research route for the above scheme is as follows:

[0032] In view of the fact that the medium in the gain module will generate heat, causing the laser wavefront distortion and the output laser beam quality to deteriorate, a research route that closely combines theory and experiment is adopted. By establishing a theoretical calculation model for the evolution of the thermally induced distortion of the gain module in an unstable cavity, the time domain and spatial domain characteristics of the optical distortion in the unstable cavity are obtained as the input interface of the intracavity aberration compensation strategy; according to the difference in suppression methods, the intracavity wavefront distortion is divided into high-order and medium-low-order, and their characteristics and influence on the beam quality are studied respectively. Based on dynamic experiments (active cavity), the suppression effects of the two types of aberrations are studied in order to obtain a universal and effective wavefront distortion compensation method for large-mode volume unstable cavities with multi-physical field coupling. Relying on the existing direct liquid-cooled sheet laser modules, deformable mirrors and other experimental equipment in the laboratory, a suitable resonant cavity is built, and the suppression effect of the correction method is comprehensively verified under passive and active cavity conditions.

[0033] The details are as follows:

[0034] 1. Study on the evolution law of aberration in unstable cavity under high thermal load due to thermal-optical multi-field coupling;

[0035] 2. Research on the method of suppressing high-order wavefront distortion in unstable cavities due to thermal-optical coupling: quantitative analysis of high-order wavefront distortion, optimization and improvement of unstable cavities, parameter simulation and optimization of high-order filtering devices, and research on the suppression effect of high-order distortion in cavities;

[0036] 3. Research on non-conjugate compensation strategy for low- and medium-order wavefront distortion in unstable cavities due to thermal-optical coupling: optimization and theoretical analysis of non-conjugate compensation methods, and verification of non-conjugate compensation effects in passive unstable cavities;

[0037] 4. Verification of the compensation effect of wavefront distortion suppression in laser unstable cavity under strong thermal-optical coupling: experimental verification of theoretical simulation results of wavefront distortion in laser unstable cavity under strong thermal-optical coupling and verification of theoretical model, verification of the compensation effect of wavefront distortion suppression in laser unstable cavity under strong thermal-optical coupling.

[0038] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0039] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An unstable cavity laser with compensation function, comprising a cavity mirror, a gain module (7) and a pump source (8); characterized in that: Also includes distortion compensation system, The distortion compensation system includes a real-time online compensation system and a high-order distortion compensation system; The real-time online compensation system comprises two 633nm semi-transparent and semi-reflective mirrors (13), a 633nm light source (12), a deformable mirror 1 (2), a deformable mirror 2 (3), a far-field and near-field tester (9), a power tester (11), and a control system; The high-order distortion compensation system includes a lens system and an aperture.

2. The unstable cavity laser with compensation function according to claim 1, characterized in that: The cavity mirror comprises a concave reflector (1), a scraper mirror (4), and a convex reflector (6).

3. The unstable cavity laser with compensation function according to claim 1, characterized in that: The cavity mirror comprises a concave reflector (1), a scraper mirror (4), and a concave reflector (14).

4. The unstable cavity laser with compensation function according to claim 1, characterized in that: The gain module (7) is equipped with a Nd:YAG laser gain crystal and a cooler.

5. The unstable cavity laser with compensation function according to claim 1, characterized in that: The far and near field tests (9) have two sets, one set is used for real-time online compensation system testing, and the other set is used for output testing of unstable cavity lasers.

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