Impulse Response Characteristics Of Chirped Volume Bragg Gratings

In this work, the frequency domain and time domain response analysis model of ultrashort pulses via chirped volume Bragg grating (CVBG) is constructed based on the matrix method. Aiming at the bandwidth requirement of CVBG for the hundred-femtosecond (fs) fiber chirped pulse amplification (FCPA) system, we systematically study the influence of the diffraction bandwidth on the pulse stretching and compression effect of CVBG and the impulse response characteristics of the broadband CVBG to incident pulse with different chirp parameters. The results show that the diffraction bandwidth of CVBG increases linearly with the increasing chirp rate and thickness. When the diffraction bandwidth of CVBG is smaller than that of the incident pulse, the shearing of the spectral components will cause distortion of the stretched pulse and broadening of the compressed pulse with respect to the incident pulse. To achieve stretching-compression reciprocity of the one-hundred-femtosecond pulse, it is necessary to ensure the diffraction bandwidth of CVBG no less than 60 nm. As designed, a broadband CVBG with 10 mm thickness is stretched first and then compressed, and linear chirp pulses with a spectral width of 16.64 nm arc obtained. All of the output pulses arc infinitely close to the Fourier transform constrained (FTL) pulse and the diffraction efficiency is as high as 84%, which provides a theoretical reference for the implementation of the fs CVBG pulse compressor.