Narrow-linewidth external cavity semiconductor laser linear array based on diffraction grating array

Abstract

The invention discloses a narrow-linewidth external cavity semiconductor laser linear array based on a diffraction grating array. The laser linear array comprises a semiconductor laser linear array, the semiconductor laser linear array consists of a gain waveguide, a fast axis collimating mirror and a waveguide grating, a small lens, a half-wave plate, a large lens and the diffraction grating array are sequentially arranged along the laser output direction of the semiconductor laser linear array, the distance between the small lens and the semiconductor laser linear array is the focal length f1 of the small lens, the small lens and the large lens are placed in a confocal mode to form an inverted telescopic system, the distance between the large lens and the diffraction grating array is thefocal length f2 of the large lens, the half-wave plate is located at the focal point of the small lens and the large lens, the diffraction grating array is formed by gluing diffraction grating unitswith different rotation angles, and each diffraction grating unit is placed in a Littrow structure. According to the invention, the overall spectral line width is reduced, the optical path structure is simplified, and the device stability is improved.

Description

technical field [0001] The invention relates to a narrow line width external cavity semiconductor laser line array based on a diffraction grating array. Background technique [0002] There is inherent thermal stress in the process of bonding the laser line array with the heat sink, so that each light-emitting unit in the line array is not on a straight line and bends. When using the entire diffraction grating external cavity feedback for spectral compression, such as figure 1 As shown, the light-emitting unit a on the optical axis (z-axis) and the off-axis light-emitting unit b are incident on the grating at different angles. When the diffraction grating is a Littrow structure, the center wavelength of the feedback light returning from the original path is different. Different from the central wavelength of the spectrum output by the off-axis light-emitting unit, the overall spectrum of the semiconductor laser line array is the superposition of the spectra of each light-emi...

AI Technical Summary

Problems solved by technology

The disadvantage of this scheme is that due to the grating Littmann structure, when the light is reflected by the feedback mirror and enters the grating again, the first-order diffracted light is fed back to the laser, and the zero-order diffracted light is lost, so the output power is low

In addition, due to the introduction of the feedback mirror, the number of optical elements increases, so the adjustment of the optical path is complicated and difficult to adjust

Patent No. 2007200944437 The diffraction grating array external cavity semiconductor laser line array has the problems of complex structure of the diffraction grating array external cavity semiconductor laser line array, many optical path components, and spectral broadening of the line array

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