非相干光纤激光组束系统耦合效率的优化分析

The optimization of the coupling efficiency in incoherent fiber laser beam combination

单光束耦合效率是决定非相干组束系统输出功率的关键,它受到透镜焦距、光栅周期和光斑半径等参数的影响。为了寻求较为优化的系统参数,通过理论分析和仿真研究,结果表明对于中心波长1060nm的光纤激光,应当选择透镜焦距20cm,光栅周期5μm,并且需要将光斑半径控制在50μm左右。通过反解光栅频率及组束波长带宽的第一个零点来选择组束阵列宽度一定条件下较优的光栅参数。通过理论分析和数值计算,结果表明较小的光栅频率和光栅厚度对提高衍射效率是有利的。

The single beam＇s coupling effidency is the key to the combined output power in incoherent fiber laser beam combination system, which is affected by focal length of lens, grating period and light spot radius. In order to find out the optimum system parameters, the theoretical analysis and numerical simulations are developed. It is proved that for the fiber laser whose central wavelength is 1060nm, the fcocal length should be chosen as 20cm, the grating period as 5μm, also the light spot radius should be controlled to be around 50μm. The optimum parameters under certain combining array width could be selected by the first zero points of grating frequency and combining wavelength deviation. Through theoretical analysis and numerical calculations, it is proved that the lower grating frequency and grating thickness was favorable to improve the diffractive efficiency.