建立了用光热折变无机玻璃反射式体布拉格光栅实现高功率光纤激光器谱合成的物理模型,在考虑高功率激光导致的体布拉格光栅表面热形变情况下,将体光栅进行分片处理后,采用有限差分Crank-Nicholson和稀疏矩阵方法,通过反复迭代求解波动方程,数值计算了两束光纤激光经不同形变的体布拉格光栅谱合成后的光强分布、桶中功率和合成效率,并定量分析了光栅形变对合成光束光强分布、桶中功率和合成效率的影响。研究结果表明,高功率激光导致的体布拉格光栅表面的热形变不仅会导致合成光束的光束质量变差,而且还会引起谱合成系统合成效率的迅速下降。 The physical model of high-power fiber laser spectrum synthesis using the Bragg grating with photo-thermal-refractive inorganic Bragg grating was established. After the bulk grating was sliced ​​by considering the thermal deformation of the Bragg grating caused by high-power laser, The finite-difference Crank-Nicholson and sparse matrix method were used to solve the wave equation by iterative iterative method. The light intensity distribution, the power and the synthesis efficiency of the two bundles of fiber Bragg gratings were numerically calculated and quantitatively analyzed The influence of grating deformation on the light intensity distribution, the power in the barrel and the efficiency of the synthesis are analyzed. The results show that the thermal deformation of the Bragg grating caused by high power laser can not only deteriorate the beam quality of the composite beam, but also lead to the rapid decline of the synthesis efficiency of the spectral synthesis system.