体光栅光谱合成技术是获得高功率激光输出的一种有效途径,体光栅衍射旁瓣引起的串扰是影响合成效率的重要因素。基于Kogelnik的耦合波理论,分析了体光栅光谱合成系统的模型,对体光栅旁瓣引起的串扰损耗进行了计算仿真;推导并简化了有串扰情况下的多路激光光谱合成效率公式。数值分析结果表明:体光栅的串扰损耗主要来源于一级至四级旁瓣,随着相邻光束的波长间距的增大,体光栅对光束的串扰损耗逐渐降低。简化后的合成效率公式计算得到的结果与简化前的公式所得结果相差小于0.5%。

Spectral beam combining with volume Bragg grating is an effective approach to obtain high-power laser output. The cross-talk by the side-lobe of the volume Bragg grating is the main factor impacting the combining efficiency of spectral beam combining. A model of spectral combining system of multi-channels laser beams with volume Bragg grating(VBG)is established, based on the Kogelnik theory of coupled waves. The cross-talk by the side-lobe of the VBG is simulated. By considering the cross-talk, the function of multi-channels laser combining efficiency is built and predigested. Numerical results show that the cross-talk of the VBG is mainly resulted from the first, second, third and forth order side-lobe. As the wavelength separation of the beam closed is raised, the cross-talk of the transmission reduces. The results between the predigested combining efficiency function and the original function are less than 0.5%, which meet the requirement.