Method for reducing polarization loss of laser

Abstract

The invention discloses a method for reducing the polarization loss of a laser, and the method comprises the following steps: arranging a first reflector and an emergent mirror in a resonant cavity, and arranging a polarization element on a light path between the first reflector and the emergent mirror, a quarter-wave plate, a pump light source module and a Q-switching module are arranged on a light path between the polarization element and the first reflecting mirror, the emergent mirror is located on the linearly polarized light emergent side of the polarization element, and a second reflecting mirror is arranged on a reflecting light path of the polarization element. The invention solves the problems of serious polarization loss and low light-to-light conversion efficiency of the resonant cavity of the large-energy laser in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to a method for reducing laser polarization loss. Background Technology

[0002] When high-energy or high-power acousto-optic and passively Q-switched solid-state lasers that need to generate linearly polarized laser light are operating, the high pump power generates enormous waste heat in the gain medium, leading to a non-uniform temperature distribution within the laser gain medium. Typically, the temperature is high at the center and low at the edges. This non-uniform heat distribution generates thermal stress within the medium. For isotropic optical materials, they are optically isotropic in the stress-free state, and their refractive index is independent of the polarization and propagation directions of light. However, once thermal stress is applied, the material becomes anisotropic, producing a "stress birefringence" effect.

[0003] Due to the "stress birefringence" effect, the polarization state inside the resonant cavity changes and the degree of polarization decreases. If there are polarization devices inside the cavity, light that deviates from the designed polarization state will generate additional reflection, scattering, or absorption losses on these components.

[0004] Current technology allows for the addition of a 90° quartz rotator within the resonant cavity, which can partially compensate for the "stress birefringence" effect after one round trip within the cavity. However, since it only involves one round trip, the compensation efficiency is not high, and the uncompensated laser light is still lost due to the polarization elements, resulting in low laser-to-optical conversion efficiency and severe polarization loss in the resonant cavity. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for reducing the polarization loss of lasers, thereby solving the problem of severe polarization loss in high-energy solid-state lasers in the prior art.

[0006] This invention achieves this objective through the following technical solution: A method for reducing laser polarization loss includes the following: a first reflector and an exit mirror are disposed in a resonant cavity; a polarizer is disposed in the optical path between the first reflector and the exit mirror; a quarter-wave plate, a pump source module, and a Q-switching module are disposed in the optical path between the polarizer and the first reflector; the exit mirror is located on the linearly polarized light output side of the polarizer; and a second reflector is disposed in the reflected optical path of the polarizer.

[0007] Furthermore, the pump source module includes a pump source and a laser crystal.

[0008] Furthermore, the Q-switching module is an acousto-optic Q-switching module or a passive Q-switching module.

[0009] Furthermore, the polarizing element includes a polarizer and a polarizing prism.

[0010] Compared with the prior art, the beneficial effects of this invention are as follows: This invention provides a method for reducing laser polarization loss, solving the problems of severe polarization loss and low optical-to-optical conversion efficiency in high-energy laser resonators in the prior art. A mirror is added to the reflected light path of the polarization element, reflecting the laser light lost due to polarization loss back into the cavity to participate in oscillation. After multiple round-trip oscillations, the laser light that would otherwise suffer from polarization loss is compensated to the designed polarized light, which is then output from the output mirror. This improves the compensation efficiency, thereby increasing the optical-to-optical conversion efficiency and reducing the resonator polarization loss. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the optical path inside the resonant cavity of the present invention.

[0012] In the figure, the following labels are used: 1-first reflecting mirror; 2-Q-switching module; 3-polarizing element; 4-laser oscillation optical path; 5-pump source; 6-laser crystal; 7-quarter-wave plate; 8-second reflecting mirror; 9-output mirror. Detailed Implementation

[0013] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0014] This invention discloses a method for reducing laser polarization loss, comprising the following: a first reflecting mirror 1 and an exiting mirror 9 are arranged in a resonant cavity; a polarizing element 3 is arranged in the optical path between the first reflecting mirror 1 and the exiting mirror 9; a quarter-wave plate 7, a pump source module, and a Q-switching module 2 are arranged in the optical path between the polarizing element 3 and the first reflecting mirror 1; the exiting mirror 9 is located on the linearly polarized light emitting side of the polarizing element 3; a second reflecting mirror 8 is arranged in the reflected light path of the polarizing element 3; and the pump source module consists of a pump source 5 and a laser crystal 6.

[0015] The laser oscillation optical path 4 formed by the method of the present invention is as follows: Figure 1 As shown, by adding a second reflector 8, the laser light lost by the polarization element 3 is reflected back into the cavity to participate in oscillation. After multiple round trips of oscillation, the laser light that should have been lost due to the polarization element 3 is compensated to the designed polarized light, and then output from the output mirror 9, thereby improving the compensation effect and reducing polarization loss.

[0016] In this invention, the quarter-wave plate 7, the Q-switching module 2, and the laser crystal 6 are not limited to one position and can be set at any position in the optical path between the polarizing element 3 and the first reflector 1.

[0017] In this invention, the Q-switching module 2 can be an acousto-optic Q-switching module or a passive Q-switching module.

[0018] In this invention, the polarization element 3 can be a polarizing beam splitter or a polarizer.

[0019] The resonant cavity in the invention can be designed as a folded cavity according to requirements, and is not limited to a straight cavity, such as a Z-shaped cavity, an L-shaped cavity, etc.

[0020] The present invention has been described in detail above through embodiments, but the content described is only an exemplary embodiment of the present invention and should not be considered as limiting the scope of the present invention. The scope of protection of the present invention is defined by the claims. Any technical solutions designed by those skilled in the art using the technical solutions described in the present invention, or similar technical solutions designed by those skilled in the art under the inspiration of the technical solutions of the present invention, within the substance and scope of protection of the present invention, to achieve the above-mentioned technical effects, or equivalent changes and improvements made to the scope of the application, should still fall within the patent protection scope of the present invention. It should be noted that, for clarity, descriptions of some components and processes that are not directly and obviously related to the scope of protection of the present invention but are known to those skilled in the art have been omitted in the description of the present invention.

Claims

1. A method of reducing polarization mode dispersion in a laser, characterized by, The application relates to a resonant cavity laser device, which comprises the following: a first reflecting mirror and an exit mirror are arranged in the resonant cavity; a polarization element is arranged on the light path between the first reflecting mirror and the exit mirror; a quarter-wave plate, a pump light source module and a Q-switching module are arranged on the light path between the polarization element and the first reflecting mirror; the exit mirror is located on the linearly polarized light exit side of the polarization element; and a second reflecting mirror is arranged on the reflection light path of the polarization element.

2. The method of claim 1, wherein the step of reducing the polarization mode dispersion of the laser comprises the step of: The pump source module comprises a pump source and a laser crystal.

3. The method of claim 1, wherein the step of reducing the polarization mode dispersion of the laser comprises the step of: The Q-switching module is an acousto-optic Q-switching module or a passive Q-switching module.

4. The method of claim 1, wherein the step of reducing the polarization mode dispersion of the laser comprises the step of: The polarization element comprises a polaroid and a polarization prism.

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