CN107404061A - A kind of semiconductor laser outer cavity coherent closes beam system - Google Patents

Abstract

This application discloses a kind of semiconductor laser outer cavity coherent to close beam system, the system using reflecting module replace Darman raster realize the exit face of noise spectra of semiconductor lasers second laser wavelength locking and reflection, reduce due to using Darman raster realize wavelength locking and the zone of reflections come substantial amounts of laser energy loss；And the reflecting module can change the distance in the laser emitting direction of the semiconductor laser and the semiconductor laser by control module, the purpose of different light paths is selected so as to realize for the shoot laser wavelength of different semiconductor lasers, light path need not be changed by mobile semiconductor laser during coherently combined, and then reduce the stability requirement during coherently combined for semiconductor laser.

Description

A semiconductor laser external cavity coherent beam combining system

technical field

The present application relates to the technical field of lasers, and more specifically, to a semiconductor laser external cavity coherent beam combining system.

Background technique

Laser (Light Amplification by Stimulated Emission of Radiation, LASER) has the characteristics of high brightness, directivity, monochromaticity and good coherence, and is widely used in various fields of production and life.

Among all kinds of lasers that generate lasers, semiconductor lasers have the advantages of high efficiency, small volume, long life, and easy integration. However, semiconductor laser unit devices often have low power, large divergence angle, and beam quality that cannot meet industrial and military requirements. Therefore, it is necessary to solve the above problems by combining bundles.

Currently known beam combining methods include: spatial beam combining, waveguide beam combining, spectral beam combining, coherent beam combining, and polarization beam combining; among these beam combining methods, coherent beam combining has obvious advantages in improving beam quality , however, coherent beam combining has very strict requirements on the phase, and it is necessary to move the semiconductor laser to change the optical path during the adjustment process to achieve coherent phase cancellation; For the Dammann grating, the diffraction efficiency of the Dammann grating is about 77%, and some energy will be lost.

Contents of the invention

In order to solve the above technical problems, the present invention provides a semiconductor laser external cavity coherent beam combining system to reduce the stability requirements of semiconductor lasers in the process of semiconductor laser coherent beam combining and reduce the laser energy loss of semiconductor lasers Purpose.

In order to achieve the above technical objectives, the embodiments of the present invention provide the following technical solutions:

A semiconductor laser external cavity coherent beam combining system is applied to a laser system with multiple semiconductor lasers, and the semiconductor laser external cavity coherent beam combining system includes: a laser processing module, a first collimation module, a second collimation module and reflection module; where,

The first collimation module and the laser processing module are sequentially arranged on the side of the first exit surface of the plurality of semiconductor lasers;

The second collimation module and the reflection module are sequentially arranged on the side of the second exit surface of the plurality of semiconductor lasers;

The collimation module is used to collimate the outgoing laser light of the semiconductor laser;

The reflective module can move in the laser emitting direction of the semiconductor laser, and is used to lock the laser light emitted from the second emitting surface of the semiconductor laser at a preset wavelength, and return along the original optical path to communicate with the first laser beam of the semiconductor laser. The laser beams emitted from the exit surface are coherently combined to form the laser to be processed;

The laser processing module is used for performing optical processing on the incident laser light to be processed, and then emitting it, so as to obtain the outgoing laser light.

Optionally, the first collimation module includes N sub-collimation units, and the second collimation module includes N sub-collimation units;

The sub-collimation unit includes a fast-axis collimator and a slow-axis collimator sequentially arranged along the central optical axis of the exit surface of the semiconductor laser;

The surface of the fast axis collimating mirror away from the semiconductor laser has an anti-reflection film;

The surface of the slow axis collimator facing away from the semiconductor laser has an anti-reflection film;

N is equal to the number of the semiconductor lasers, and one sub-collimation unit corresponds to one semiconductor laser.

Optionally, the reflective module includes N reflective optical devices;

The central optical axis of one reflective optical device coincides with the central optical axis of the exit surface of one semiconductor laser;

N is equal to the number of the semiconductor lasers, and one reflective optical device corresponds to one semiconductor laser.

Optionally, the reflective optical device is a diffraction grating or a reflective mirror.

Optionally, the diffraction efficiency of the diffraction grating is greater than or equal to 95%.

Optionally, the reflectivity of the mirror meets the requirements for laser oscillation.

Optionally, the laser processing module includes: a Fourier transform lens, a spatial filter, and an output coupling mirror; wherein,

The central optical axes of the Fourier transform lens, the spatial filter and the output coupling mirror coincide;

The plurality of semiconductor lasers are symmetrically arranged with respect to the central optical axis of the Fourier transform lens;

The surface of the output coupling mirror facing away from the spatial filter has an anti-reflection film, and the surface of the output coupling mirror facing the spatial filter has a reflective film.

Optionally, the output coupling mirror is a plano-concave lens, the concave surface of the plano-concave lens is disposed toward the side of the Fourier transform lens, and the concave surface of the plano-concave lens is complementary to the convex surface of the Fourier transform lens.

Optionally, it also includes: a control module;

The control module is used to control the reflection module to move in the laser emitting direction of the semiconductor laser.

Optionally, the control module is a stepping motor or a motor.

It can be seen from the above technical solutions that the embodiment of the present invention provides a semiconductor laser external cavity coherent beam combining system, which uses a reflective module instead of a Damman grating to achieve wavelength locking and reflection of the laser emitted from the second exit surface of the semiconductor laser , reducing the large amount of laser energy loss due to wavelength locking and reflection using the Damman grating; and the reflection module can move in the laser emission direction of the semiconductor laser to change the laser emission direction of the semiconductor laser The distance from the semiconductor laser, so as to achieve the purpose of selecting different optical paths for different laser wavelengths of different semiconductor lasers, does not need to change the optical path by moving the semiconductor laser in the process of coherent beam combining, thereby reducing the coherence. Stability requirements for semiconductor lasers during beam combining.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

FIG. 1 is a schematic structural diagram of a semiconductor laser external cavity coherent beam combining system provided by an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a semiconductor laser external cavity coherent beam combining system provided by another embodiment of the present application.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

An embodiment of the present application provides a semiconductor laser external cavity coherent beam combining system, as shown in Figure 1, which is applied to a laser system with multiple semiconductor lasers A10, and the semiconductor laser A10 external cavity coherent beam combining system includes: laser processing module 300, the first collimation module 100, the second collimation module 200 and the reflection module 400; wherein,

The first collimation module 100 and the laser processing module 300 are sequentially arranged on the side of the first exit surface of the plurality of semiconductor lasers A10;

The second collimation module 200 and the reflection module 400 are sequentially arranged on the side of the second exit surface of the plurality of semiconductor lasers A10;

The collimation module is used for collimating the outgoing laser light of the semiconductor laser A10;

The reflective module 400 can move in the laser emitting direction of the semiconductor laser, and is used to lock the laser emitted from the second emitting surface of the semiconductor laser A10 at a preset wavelength, and reflect it along the original optical path to be compatible with the semiconductor laser. The laser beams emitted from the first exit surface of A10 are coherently combined to form the laser to be processed;

The laser processing module 300 is used for performing optical processing on the incident laser light to be processed, and then emitting it, so as to obtain outgoing laser light.

Referring to FIG. 1 , after the laser light emitted from the second emitting surface of the semiconductor laser A10 is collimated by the second collimation module 200, its fast-axis divergence angle and slow-axis divergence angle are compressed, and the fast-axis and slow-axis divergence angles are compressed. Exit in the form of near-parallel light. After the reflection of the reflection module 400, the emitted laser light is locked at the preset wavelength, and returns to the semiconductor laser A10 along the original optical path, and is emitted from the first exit of the semiconductor laser A10. Surface emission, coherently combined with the laser light emitted from the first exit surface of the semiconductor laser A10 to form the laser to be processed;

The laser to be processed is emitted after being processed by the laser processing module 300 through Fourier transform, filtering, resonance, amplification and phase locking, and the emitted laser is called the outgoing laser.

The diffraction efficiency of the diffraction grating is preferably greater than or equal to 95%.

It should be noted that the system uses the reflective module 400 instead of the Damman grating to achieve wavelength locking and reflection of the laser emitted from the second exit surface of the semiconductor laser A10, which reduces a large number of problems caused by using the Damman grating to achieve wavelength locking and reflection. Laser energy loss; and the reflective module 400 moves in the laser emission direction of the semiconductor laser to change the distance between the laser emission direction of the semiconductor laser A10 and the semiconductor laser A10, so as to achieve different semiconductor lasers A10 The purpose of selecting different optical paths according to the output laser wavelength is that it is not necessary to change the optical path by moving the semiconductor laser A10 in the process of coherent beam combining, thereby reducing the stability requirements for the semiconductor laser A10 in the process of coherent beam combining.

On the basis of the above embodiments, in one embodiment of the present application, referring to FIG. 1, the first collimation module 100 includes N sub-collimation units M10, and the second collimation module 200 includes N sub-collimation units M10. Collimation unit M10;

The sub-collimation unit M10 includes a fast-axis collimator M11 and a slow-axis collimator M12 arranged sequentially along the central optical axis of the exit surface of the semiconductor laser A10;

The surface of the fast axis collimating mirror M11 facing away from the semiconductor laser A10 has an anti-reflection film;

The surface of the slow-axis collimating mirror M12 facing away from the semiconductor laser A10 has an anti-reflection film;

N is equal to the number of the semiconductor lasers A10, and one sub-collimation unit M10 in the collimation module corresponds to one semiconductor laser A10.

Optionally, the reflective module 400 includes N reflective optical devices;

A central optical axis of the reflective optical device coincides with a central optical axis of the exit surface of the semiconductor laser A10;

N is equal to the number of the semiconductor lasers A10, and one reflective optical device corresponds to one semiconductor laser A10.

Optionally, referring to FIG. 1 and FIG. 2 , the reflective optical device is a diffraction grating 410 or a reflective mirror 420 .

It should be noted that the distance between each reflective optical device in the reflective module 400 and its corresponding semiconductor laser A10 can be adjusted by the control module, so as to realize the change of the optical path from the laser emitted by the semiconductor laser A10 to the reflective optical device .

When the spectral width of the semiconductor laser A10 is narrow and there are few modes, the reflective mirror 420 can be used as the reflective optical device; correspondingly, when the spectral width of the semiconductor laser A10 is wide and there are many modes, A diffraction grating 410 is preferably used as the reflective optical device.

The diffraction efficiency of the diffraction grating 410 used is preferably greater than or equal to 95%, and the reticle, polarization and wavelength of the diffraction grating 410 depend on the specific circumstances;

The reflectivity of the reflective mirror 420 used is preferably greater than 99%, so as to meet the requirements for laser oscillation.

Optionally, the semiconductor laser A10 may be a single-tube semiconductor laser A10, a linear array semiconductor laser A10, or a stacked semiconductor laser A10.

On the basis of the above embodiments, in yet another embodiment of the present application, still referring to FIG. 1 , the optical processing module includes: a Fourier transform lens 310, a spatial filter 320, and an output coupling mirror 330; wherein,

The central optical axes of the Fourier transform lens 310, the spatial filter 320 and the output coupling mirror 330 coincide;

The plurality of semiconductor lasers A10 are symmetrically arranged about the central optical axis of the Fourier transform lens 310;

The surface of the output coupling mirror 330 facing away from the spatial filter 320 has an anti-reflection film, and the surface of the output coupling mirror 330 facing the spatial filter 320 has a reflective film.

It should be noted that the reflectivity of the antireflection film on the surface of the fast axis collimating mirror M11, the slow axis collimating mirror M12, and the output coupling mirror 330 is preferably less than 1%, and the reflection rate of the reflecting film on the surface of the output coupling mirror 330 is The preferred range for the rate is 9% to 60%, inclusive. This application does not limit its specific value, which depends on the actual situation.

The spatial filter 320 can filter out the mode of the fast axis in the laser, and can also filter out the mode of the slow axis in the laser, depending on actual needs.

Preferably, the output coupling mirror 330 is a plano-concave lens, the concave surface of the plano-concave lens is set towards the side of the Fourier transform lens 310, and the concave surface of the plano-concave lens is in contact with the convex surface of the Fourier transform lens 310 complementary.

It should be noted that the concave surface of the plano-concave lens is complementary to the convex surface of the Fourier transform lens 310, which can also be referred to as that the concave surface radius of the plano-concave lens is equal to the convex surface radius of the Fourier transform lens 310, so that The purpose is to ensure that the laser light reflected by the reflective film of the plano-concave lens can return to the original optical path and enter the semiconductor laser A10 as the feedback laser light.

On the basis of the above embodiments, in a preferred embodiment of the present application, the semiconductor laser external cavity coherent beam combining system further includes: a control module;

The control module is used to control the reflection module 400 to move in the laser emitting direction of the semiconductor laser.

Optionally, the control module may be a stepping motor, or a motor, and the accuracy of adjusting the distance is related to the laser wavelength of the semiconductor laser A10. However, in other embodiments of the present application, the distance between the reflective module in the laser emission direction of the semiconductor laser A10 and the semiconductor laser A10 can also be adjusted manually. This application does not limit it, and it depends on the actual situation.

To sum up, the embodiment of this application provides a semiconductor laser A10 external cavity coherent beam combining system, which uses the reflection module 400 instead of a Damman grating to achieve wavelength locking and reflection of the laser emitted from the second exit surface of the semiconductor laser A10 , which reduces the large amount of laser energy loss due to wavelength locking and reflection using the Damman grating; and the reflection module 400 can change the laser emission direction of the semiconductor laser A10 and the distance, so as to achieve the purpose of selecting different optical paths for different wavelengths of laser light emitted by different semiconductor lasers A10. It is not necessary to change the optical path by moving the semiconductor laser A10 in the process of coherent beam combining, thereby reducing Stability requirements for semiconductor laser A10.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A semiconductor laser external cavity coherent beam combining system is characterized in that it is applied to a laser system with a plurality of semiconductor lasers, and the semiconductor laser external cavity coherent beam combining system includes: a laser processing module, a first collimation module, The second collimation module and reflection module; wherein, The first collimation module and the laser processing module are sequentially arranged on the side of the first exit surface of the plurality of semiconductor lasers; The second collimation module and the reflection module are sequentially arranged on the side of the second exit surface of the plurality of semiconductor lasers; The collimation module is used to collimate the outgoing laser light of the semiconductor laser; The reflective module can move in the laser emitting direction of the semiconductor laser, and is used to lock the laser light emitted from the second emitting surface of the semiconductor laser at a preset wavelength, and return along the original optical path to communicate with the first laser beam of the semiconductor laser. The laser beams emitted from the exit surface are coherently combined to form the laser to be processed; The laser processing module is used for performing optical processing on the incident laser light to be processed, and then emitting it, so as to obtain the outgoing laser light. 2. The system according to claim 1, wherein the first collimation module comprises N sub-collimation units, and the second collimation module comprises N sub-collimation units; The sub-collimation unit includes a fast-axis collimator and a slow-axis collimator sequentially arranged along the central optical axis of the exit surface of the semiconductor laser; The surface of the fast axis collimating mirror away from the semiconductor laser has an anti-reflection coating; The surface of the slow axis collimator facing away from the semiconductor laser has an anti-reflection film; N is equal to the number of the semiconductor lasers, and one sub-collimation unit corresponds to one semiconductor laser. 3. The system according to claim 1, wherein the reflective module comprises N reflective optical devices; The central optical axis of one reflective optical device coincides with the central optical axis of the exit surface of one semiconductor laser; N is equal to the number of the semiconductor lasers, and one reflective optical device corresponds to one semiconductor laser. 4. The system of claim 3, wherein the reflective optics are diffraction gratings or mirrors. 5. The system according to claim 4, wherein the diffraction efficiency of the diffraction grating is greater than or equal to 95%. 6 . The system according to claim 4 , wherein the reflectivity of the mirror meets the requirements for laser oscillation. 7. The system according to claim 1, wherein the laser processing module comprises: a Fourier transform lens, a spatial filter and an output coupling mirror; wherein, The central optical axes of the Fourier transform lens, the spatial filter and the output coupling mirror coincide; The plurality of semiconductor lasers are symmetrically arranged with respect to the central optical axis of the Fourier transform lens; The surface of the output coupling mirror facing away from the spatial filter has an anti-reflection film, and the surface of the output coupling mirror facing the spatial filter has a reflective film. 8. The system according to claim 7, wherein the output coupling mirror is a plano-concave lens, the concave surface of the plano-concave lens is arranged towards one side of the Fourier transform lens, and the concave surface of the plano-concave lens is in contact with The convex surfaces of the Fourier transform lens are complementary. 9. The system according to claim 1, further comprising: a control module; The control module is used to control the reflection module to move in the laser emitting direction of the semiconductor laser. 10. The system according to claim 9, wherein the control module is a stepping motor or a motor.