Spectral beam combining device for realizing spectral width compression through two-time diffraction by using grating and reflecting element

Abstract

Disclosed is a semiconductor laser spectral beam combining device for for realizing spectral width compression through two-time diffraction by using a grating and a reflecting element. The device comprises a semiconductor laser light source, a slow axis collimating cylindrical lens, a transforming lens, a grating, a reflecting element and an output coupling mirror. In the invention, the single grating is used as a diffraction element, the reflecting element reflects the beam which is diffracted by the grating for the first time, the beam is secondarily dispersed when passing through the grating again, and the dispersive power is doubled. Through the feedback of the output coupling mirror, the laser of each unit of a semiconductor laser array is locked at a different wavelength to obtain a laser output of high power and high brightness. The device of the invention overcomes the limitation of the gain line width of a gain material in the traditional spectral beam combination to the number of beam combining units, can increase the number of beam combining units within the gain line width and the high-efficiency diffraction wavelength range of the grating, increases the output power significantly, reduces the resonant cavity length with a certain spectral width, makes the laser structure compact and improves laser mode stability.

Description

technical field [0001] The invention relates to the technical field of semiconductor lasers, in particular to a semiconductor laser spectrum combining device which utilizes a grating and a reflective element to realize narrow-linewidth and high-power laser output through external cavity feedback. Background technique [0002] Semiconductor lasers have the advantages of low cost, long life, small size and high reliability, and have been widely used in industrial processing, pumping, medical treatment, communication and other fields. An important factor restricting the future development of semiconductor lasers is brightness. The brightness of the laser beam is determined by the output power and beam quality, the higher the power, the better the beam quality and the higher the brightness. [0003] Beam combining technology is a common method to realize high-brightness semiconductor lasers. Spectral beam combining is a novel beam combining technology, which mainly uses grating...

AI Technical Summary

Problems solved by technology

[0005] How to compress the spectral width of the beam combining laser is the main problem of increasing the number of combining units. The spectral width is determined by many factors, mainly in the following three categories: 1. Reducing the distance between adjacent combining units can produce high-density semiconductors The laser array or the use of optical imaging systems to compress the beam combining unit spacing, but limited by semiconductor technology, increases crosstalk between different units, cannot be fully fed back, and reduces beam combining efficiency; 2. Increase the focal length of the conversion lens, but the beam combining system The length of the coupling cavity and the length of the coupling cavity will increase accordingly, the volume of the system will become larger and the stability of the resonator system will decrease, the overall optical path will increase, and crosstalk between beam combining units is more likely to occur when the divergence angle remains the same ;3. Increasing the linear density of the grating means reducing the grating period, but the grating period is limited by the wavelength of the semiconductor laser, and the minimum grating period cannot be less than half of the wavelength. Assuming that the wavelength of the semiconductor laser is 940nm, the theoretical maximum linear density of the grating is 2127lines / mm, the linear density cannot be further improved, and the feasibility is not high

Improving the linear density of the grating is to improve the diffraction ability of the grating. The diffraction ability of the grating can also be improved by using two non-parallel gratings. In the patent, it is proposed to use two gratings placed non-parallel, and the beam combining unit passes through the diffraction effect of the grating twice. Although the spectral width is compressed by half, two gratings are used to improve the diffraction ability of the grating, and the adjustment accuracy of the system and Difficulty increases, raster cost is high, and the ability to compress line width is limited

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