Optimization of spatial filter with volume Bragg gratings in photo-thermo-refractive glass

We present a method for optimizing spatial filter performance by inserting volume Bragg gratings (VBGs) in front of the traditional spatial filters. The experimental results show that the cutoff frequency is modified with the insertion of VBGs. We also demonstrate the optimization of filtering performance in both the spatial and frequency domains, with detailed comparison of near-field modulation, contrast ratio, and power spectral density of output laser beams.