CN213125044U

CN213125044U - Device for optimizing quality of laser beam

Info

Publication number: CN213125044U
Application number: CN202021628748.3U
Authority: CN
Inventors: 陈政; 罗薇; 傅立斌
Original assignee: Acculasers Co ltd
Current assignee: Acculasers Co ltd
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2021-05-04
Anticipated expiration: 2030-08-07

Abstract

The utility model discloses an optimize laser beam quality device, include: the resonant cavity assembly and the light beam in-out assembly; the resonant cavity component is optically connected with the light beam in-out component, and circularly optimizes the external laser light beam passing through the light beam in-out component; the resonant cavity component is provided with a convex mirror, a dichroic mirror, a laser crystal, a first polarization beam splitting mirror, an electro-optical switch and a concave mirror which are sequentially connected in an optical mode. The utility model discloses owing to set up the resonant cavity subassembly, convex mirror and concave mirror constitute unstable resonator structure's resonant cavity to the light beam select the mould, optimize the light beam quality through unstable resonator structure and laser crystal collocation, utilize the great characteristics of unstable resonator loss, eliminate the high order mould, utilize thermal lens to replace lens can adjust unstable resonator and make the base mode make the back and forth oscillation improve the light beam quality and can obtain the gain again simultaneously, it is obvious to the light beam quality optimization effect; furthermore, the utility model discloses prior art has bigger application scope, and whole light path simple structure facilitates for in-service use.

Description

Device for optimizing quality of laser beam

Technical Field

The utility model belongs to the technical field of laser, especially, relate to an optimize laser beam quality device.

Background

In laser technology, a solid laser amplification system is the main way to effectively improve pulse energy and continuous output power at present. However, the core of the solid-state laser amplification system, i.e., the laser crystal, has considerable defects. In the pumping state, the laser crystal can continuously generate heat due to quantum loss, and the laser thermal lens phenomenon can be caused under the conditions of uneven pumping and crystal self-reason. Along with the increase of the pumping power, the thermal spherical aberration coefficient is gradually increased under the influence of the thermal lens, which is reflected in that the quality of the light beam is reduced, the light spot form is changed into the light beam quality which is a measure of the focusable degree of the laser beam, and the far field divergence angle of the high-quality light beam is close to the diffraction limit of an ideal single-mode Gaussian light beam. The beam quality is affected by the laser generation, emission and transmission processes.

There have been many thermal lens studies on laser crystals, but none have been able to alter this effect. In the prior art, through a certain amplification structure, the influence of beam quality reduction caused by thermal distortion is counteracted, and the beam quality of laser is improved.

SUMMERY OF THE UTILITY MODEL

The technical purpose of the utility model is to provide an optimize laser beam quality device, include: the resonant cavity assembly and the light beam in-out assembly;

the resonant cavity component is optically connected with the light beam in-out component, the resonant cavity component circularly optimizes the external laser beam passing through the light beam in-out component, and the light beam in-out component emits the optimized laser beam to the outside;

the resonant cavity assembly is provided with a first polarization beam splitting lens in the incident direction of external laser beams, the first polarization beam splitting lens comprises a first mirror surface and a second mirror surface, an electro-optical switch and a concave mirror which are sequentially connected in an optical mode are arranged close to the resonant cavity assembly with the first mirror surface, and a laser crystal, a dichroic lens and a convex mirror which are sequentially connected in an optical mode are arranged close to the resonant cavity assembly with the second mirror surface.

Wherein, light beam business turn over subassembly includes: a lens group and a double-pass light path component;

the double-pass optical path component is optically connected with one end of the lens group, the other end of the lens group is optically connected with the resonant cavity component, and the lens group is a two-sided lens arranged in parallel.

Specifically, the two-way optical path component includes: the second polarization beam splitter, the optical rotation lens, the Faraday optical rotator and the total reflection lens are sequentially optically connected, and the total reflection lens is optically connected with the lens group.

Further preferably, the device for optimizing the quality of the laser beam is further provided with a detection assembly, and the detection assembly comprises: electro-optical detector, M²Detector, reflector, and electrooptical detector and M respectively²The detector is optically connected to the concave mirror.

Further preferably, the laser beam quality optimizing device is further provided with a pumping source, and the pumping source is in optical connection with the dichroic mirror.

The utility model discloses owing to adopt above technical scheme, make it compare with prior art and have following advantage and positive effect:

the utility model discloses owing to set up the resonant cavity subassembly, convex mirror and concave mirror constitute unstable resonator structure's resonant cavity to the light beam select the mould, optimize the light beam quality through unstable resonator structure and laser crystal collocation, utilize the great characteristics of unstable resonator loss, eliminate the high order mould, utilize thermal lens to replace lens can adjust unstable resonator and make the base mode make the back and forth oscillation improve the light beam quality and can obtain the gain again simultaneously, it is obvious to the light beam quality optimization effect;

the electro-optical switch is used for controlling the polarization direction in the light path, and the polarization beam splitter is matched for controlling the light path direction, so that the laser oscillates back and forth in the unstable resonator, and once back and forth, a high-order mode can be eliminated, the high-order mode is continuously diffracted and consumed, and the result of improving the light beam quality is achieved;

in addition, the utility model can be built at the rear end of any optical path, has less use limitation and has wider application range than the prior art; the whole light path structure of the device is simple, the building is convenient, and the device is convenient for practical use.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.

Fig. 1 is a schematic structural diagram of a device for optimizing the quality of a laser beam according to the present invention;

fig. 2 is a schematic structural diagram of a resonant cavity of the device for optimizing the quality of a laser beam according to the present invention.

Reference numerals:

1: a convex mirror; 2: a dichroic mirror; 3: a laser crystal; 4: a first polarization beam splitting lens; 41: a first mirror surface; 42: a second mirror surface; 5: an electro-optical switch; 6: a concave mirror; 7: a pump source; 8: a detection component; 81: a mirror; 82: an electro-optical detector; 83: m²A detector; 9: a lens group; 10: a two-pass optical path component; 101: a second polarization beam splitter lens; 102: optically rotating the lens; 103: a Faraday rotator; 104: a total reflection lens.

Detailed Description

In order to more clearly illustrate embodiments of the present invention or technical solutions in the prior art, specific embodiments of the present invention will be described below with reference to the accompanying drawings. It is obvious that the drawings in the following description are only examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be obtained from these drawings without inventive effort.

For the sake of simplicity, only the parts relevant to the present invention are schematically shown in the drawings, and they do not represent the actual structure as a product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled. In this document, "one" means not only "only one" but also a case of "more than one".

The following describes a device for optimizing the quality of a laser beam according to the present invention in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more fully apparent from the following description and appended claims.

Referring to fig. 1, the present embodiment provides an apparatus for optimizing laser beam quality, including: the resonant cavity assembly and the light beam in-out assembly; the resonant cavity component is optically connected with the light beam in-out component, the resonant cavity component circularly optimizes the external laser beam passing through the light beam in-out component, and the light beam in-out component emits the optimized laser beam to the outside; the resonant cavity assembly is provided with a first polarization beam splitter 4 in the incident direction of an external laser beam, the first polarization beam splitter 4 comprises a first mirror surface 41 and a second mirror surface 42, the resonant cavity assembly close to the first mirror surface 41 is provided with an electro-optical switch 5 and a concave mirror 6 which are sequentially connected in an optical mode, and the resonant cavity assembly close to the second mirror surface 42 is provided with a laser crystal 3, a dichroic mirror 2 and a convex mirror 1 which are sequentially connected in an optical mode.

The present embodiment will now be described in detail, and a specific optical path will be described in conjunction with the present embodiment, specifically, the two-way optical path assembly 10 is composed of a second polarization splitting lens 101, an optical rotation lens 102, a faraday optical rotator 103, and a total reflection lens 104, and since the incident laser beam to be optimized and the emergent optimized laser beam both pass through the two-way optical path assembly 10, the two-way optical path assembly 10 is used to separate the incident laser beam and the emergent laser beam. A horizontally polarized laser beam (laser to be optimized) is now fed into the double-pass beam path assembly 10, the beam quality M of which²Is about 2. Firstly, laser to be optimized is incident to the second polarization splitting lens 101, the laser to be optimized enters the optical rotation lens 102 through transmitting the second polarization splitting lens 101, the second polarization splitting lens 101 and the incident direction of the laser to be optimized are in deflection arrangement at 45 degrees, and the second polarization splitting lens 101 is highly transparent to horizontal polarized light incident in the incident direction at 45 degrees and highly reflective to vertical polarized light. Optically active lens 102The laser to be optimized is received and is transmitted to the total reflection mirror 104 through the faraday rotator 103, wherein the optical rotator 102 is arranged in a left-handed 45-degree manner in the incidence direction of the laser to be optimized, and the faraday rotator 103 is a right-handed 45-degree optical rotator with the incidence direction of the laser to be optimized as a reference, so that the laser to be optimized received and reflected by the total reflection mirror 104 is still in a horizontal polarization state.

Referring to fig. 1, in this embodiment, the laser to be optimized reflected by the total reflection mirror 104 enters the lens set 9, the lens set 9 is two lenses arranged in parallel, and the two lenses are vertically arranged with the incident direction of the laser to be optimized as a reference, and an operator can adjust the beam waist position and size of the laser beam to be optimized by adjusting the position parameters of the lens set 9 to match the unstable eigen-cavity mode formed by the concave mirror 6 and the convex mirror 1.

Referring to fig. 1 and fig. 2, in the present embodiment, after the laser emission lens set 9 to be optimized is reflected into the resonant cavity through the first polarization splitting lens 4, wherein the first polarization splitting lens 4 is disposed in an inclined manner at 45 degrees with respect to the incident direction of the laser to be optimized, and is highly transparent to the vertical polarized light incident in the incident direction of 45 degrees and highly reflective to the horizontal polarized light incident in the incident direction of 45 degrees. After being reflected by the first polarization splitting lens 4, the laser to be optimized firstly passes through the electro-optical switch 5, at this time, the electro-optical switch 5 is in an on state, the polarization direction of the laser to be optimized is changed from horizontal to vertical, and the laser to be optimized is output to the concave mirror 6, wherein the electro-optical switch 5 is the electro-optical switch 5 with the wavelength of one half, is used for converting the horizontal polarization of the laser beam into vertical polarization and controlling a light path, and has the function equivalent to a pockels cell. The concave mirror 6 is a plano-concave mirror, and certainly, the concave mirror 6 may be a concave mirror 6 with other shapes, the concave surface of which is plated with a film surface of high-reflection laser, the received laser to be optimized is reflected, the laser to be optimized passes through the electro-optical switch 5, and the electro-optical switch 5 is in a closed state, so that the polarization direction of the laser to be optimized is still in a vertical direction. After passing through the electro-optical switch 5, the laser is input to the first polarization beam splitter 4, and since the laser bias direction is the vertical direction and the first polarization beam splitter 4 is highly transparent to the vertically polarized light incident in the incident direction of 45 degrees, the laser penetrates through the first polarization beam splitter 4 directly. Laser penetrates through the first polarization beam splitter 4 and then is reflected to the convex mirror 1 through the laser crystal 3 and the dichroic mirror 2 in sequence, wherein the laser crystal 3 is an a-cut Nd: YVO4 crystal, which has the functions of providing a thermal lens in a cavity to enable fundamental mode light to stably oscillate and provides energy supplement for a power-loss laser beam; the dichroic lens 2 is a light splitting lens which is highly transparent to pump light in the 45-degree incidence direction and highly reflective to laser light, so that the laser light is reflected when passing through the dichroic lens 2; the convex mirror 1 is a plano-convex lens, but may be a convex mirror 1 with other shapes, and the convex surface is also coated with a high-reflectivity laser film surface.

Then, after the laser light hits the convex mirror 1, the laser light returns in the reverse order of the moving direction of the laser light in the cavity, that is, the laser light returns from the convex mirror 1 through the dichroic mirror 2, the laser crystal 3, the first polarization splitting mirror 4, the electro-optical switch 5 for turning off the voltage, and the concave mirror 6, and when the laser light returns to travel between the first polarization splitting mirror 4 and the electro-optical switch 5, a cycle of the laser light beam running in the cavity is defined. Therefore, the laser can continuously circulate in a cavity formed between the convex mirror 1 and the concave mirror 6, energy gain can be obtained every time the laser crystal 3 passes through in the circulation process, and the effect of optimizing the beam quality is achieved through repeated circulation.

The principle is as follows: the mode selection is carried out on the laser beam through an unstable resonator structure formed by the convex mirror 1 and the concave mirror 6. Unstable cavity structures generally do not achieve self-reproduction of modes in the cavity, and therefore, it is necessary to change the cavity parameters through the laser crystal 3, i.e., the crystal thermal lens, so that the fundamental mode can oscillate stably in the unstable cavity. In general, unstable cavity structures are used to provide an oscillating region of large cross-sectional area and stable fundamental transverse mode output. By using the characteristic of large diffraction loss of the unstable cavity structure, high-order modes in a laser beam are filtered out completely. A one-half wavelength electro-optical switch 5 is used to form a structure similar to a regenerative amplification cavity. The introduced laser beam oscillates in the cavity for many times and the high-order mode is continuously diffracted and consumed, so that the result of improving the quality of the laser beam is achieved.

An electro-optical switch 5 is added in an unstable cavity formed by a concave mirror 6 and a convex mirror 1 to control the polarization direction in a light path, and the polarization beam splitter is matched to control the direction of the light path, so that laser oscillates back and forth in the unstable cavity, and a high-order mode can be eliminated once back and forth. Meanwhile, the crystal thermal lens is used for replacing the lens, so that the mode output of the unstable cavity can be adjusted, and the laser can obtain gain.

Referring to fig. 1, after the quality of the laser beam is optimized, the electro-optical switch 5 is turned on after the laser beam is reflected by the concave mirror 6, so that the polarization direction of the optimized laser beam is changed from the vertical direction to the horizontal direction, and the optimized laser beam is reflected by the first polarization splitting mirror 4 out of the resonant cavity of the present embodiment due to the characteristics of the first polarization splitting mirror 4, and then is emitted to the outside through the lens group 9, the total reflection mirror 104, the faraday rotator 103, the optical rotation mirror 102 and the second polarization splitting mirror 101. The quality of the laser beam after being emitted is about 1.2, and the power loss is less.

Preferably, a pump source 7 is further provided in this embodiment, the pump source 7 is optically connected to the dichroic mirror 2 in the resonant cavity, the pump light emitted by the pump source is incident at 45 degrees to the dichroic mirror 2, and according to the characteristics of the dichroic mirror 2, the pump light penetrates through the dichroic mirror 2 and is transmitted to the laser crystal 3, and the pump light provides energy for the gain laser of the laser crystal 3.

Preferably, referring to fig. 1, a detection assembly 8 may be further provided in the present embodiment, and the detection assembly 8 is built on the side of the concave mirror 6 not reflecting the laser light. This detection component 8 includes: mirror 81, electro-optical detector 82 and M²Detector 83 by aligning electro-optical detector 82 and M²The data collected by the detector 83 is uploaded to a computing terminal for analysis, so as to adjust the position of the lens group 9, thereby realizing a better light beam improvement process and avoiding more energy loss. In addition, in this embodiment, an electrically controlled displacement platform may be designed to be controlled by a computing terminal, so as to automatically move and adjust the position of the lens assembly 9.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, the changes are still within the scope of the present invention if they fall within the scope of the claims and their equivalents.

Claims

1. An apparatus for optimizing laser beam quality, comprising: the resonant cavity assembly and the light beam in-out assembly;

the resonant cavity assembly is optically connected with the light beam in-out assembly, the resonant cavity assembly circularly optimizes external laser beams passing through the light beam in-out assembly, and the light beam in-out assembly emits the optimized laser beams to the outside;

the resonant cavity component is provided with a first polarization beam splitting lens in the incident direction of an external laser beam, the first polarization beam splitting lens comprises a first mirror surface and a second mirror surface, an electro-optical switch and a concave mirror which are sequentially connected in an optical mode are arranged close to the first mirror surface, and the resonant cavity component is provided with a laser crystal, a dichroic lens and a convex mirror which are sequentially connected in an optical mode and are close to the second mirror surface.

2. The apparatus of claim 1, wherein the beam access assembly comprises: a lens group and a double-pass light path component;

the double-pass optical path component is optically connected with one end of the lens group, the other end of the lens group is optically connected with the resonant cavity component, and the lens group is a two-surface lens arranged in parallel.

3. The apparatus of claim 2, wherein the dual path optical path assembly comprises: the second polarization beam splitter, rotatory lens, Faraday optical rotator and total reflection lens, the second polarization beam splitter, rotatory lens, Faraday optical rotator with total reflection lens optical connection in proper order, total reflection lens with the optical connection of lens group.

4. The apparatus of claim 1, further comprising a detection assembly, the detection assembly comprising: electro-optical detector, M²A detector, a reflector, the reflector is respectively connected with the electro-optical detector and the M²The detector is optically connected to the concave mirror.

5. The apparatus of claim 1, further comprising a pump source optically coupled to the dichroic mirror.