We propose a method for the cut-off of stimulated rotational Raman scattering (SRRS) in high-power lasers after long-distance propagation via a transmission volume Bragg grating (VBG). The VBG with both spectral and angular selectivity was designed, and its application as a near-field spatial filter for SRRS cut-off was analyzed. The results show that the spectral selectivity of the VBG enables effective separation of pump light and Stokes light in the near-field, and also improves the beam quality by filtering out high-frequency components of the pump light. This method can provide a novel and effective approach for suppressing nonlinear effects and controlling the beam quality of high-power lasers.

FM-to-AM conversion for angular filtering based on transmitted volume Bragg gratings (TBGs) is discussed. Simulation results show that a narrower spectral selectivity of TBGs led to stronger FM-to-AM conversion. Good angular selectivity and a wide bandwidth for the TBGs can be obtained by controlling the grating period and thickness. FM-to-AM conversion can be effectively suppressed and the distortion criterion for the filtered beam reduces to less than 5%. FM-to-AM conversion of TBGs is demonstrated in the ‘Shenguang’ facility, and the results are in good agreement with the simulation.