二极管激光阵列光栅-外腔谱合成系统中光束串扰行为及其对合成效率的影响

Light Crosstalk and Its Effect on Combining Efficiency of Diode Laser Array Grating-External Cavity Spectral Beam Combining System

在二极管激光阵列(DLA)光栅-外腔谱合成系统中,由于变换透镜像差、光栅制作误差及"smile"工艺误差等因素的综合作用,将导致DLA发光单元间出现光束串扰。通过分析光束串扰行为的产生机理,将主要的光束串扰行为分为两类,即杂散光返回至发光单元自身,以及经外腔反馈到其他单元,进而分别导致自激振荡模式和耦合振荡模式的产生。在此基础上,给出了含串扰光注入的半导体激光器速率方程,进而推导出DLA发光单元的合成效率模型,分析了自激振荡和耦合振荡对发光单元合成效率的影响。结果表明,杂散光返回至发光单元自身,以及经外腔反馈到其他单元这两种光束串扰行为会不同程度地降低合成效率,且后者影响更大。在实际工作中,需要采取措施对光束串扰行为加以抑制。

In diode laser array（DLA） grating-external cavity spectral beam combining（SBC） system, the total effects of lens aberration, fabrication error of grating and‘smile＇effect may lead to the light crosstalk between light-emitting units of DLA. Based on the analysis of generating mechanism of light crosstalk, the main kinds of light crosstalk can be divided into two categories, including the stray light returning to the light-emitting unit itself and other units due to the feedback of external cavity, resulting in the self-oscillation and coupled oscillation. On the above basis, the diode laser rate equation involving light crosstalk has been put forward, and the combining efficiency of DLA emitters has been derived. Furthermore, the impacts of the self-oscillation and coupled oscillation on the combining efficiency have been analyzed. Results indicate that the two categories of light crosstalk involving both the stray light returning to the light-emitting unit itself and the stray light injected into other units decrease combining efficiency of light-emitting unit to different extents, and the impact of the latter is larger. In practical applications, some methods should be taken to control the light crosstalk.