| As the development of femtosecond pulse laser, large bandwidth and high peak powerof femtosecond pulse laser can be obtained. Study on the propagation and control offemtosecond pulse laser is important for laser technology. Due to the excellent angularselectivity and wavelength selectivity of transmitting volume Bragg grating (TVBG), thetechnology of angular filtering based on TVBG provides a new way for spatial filtering ofhigh-power laser beam. However，there are plentiful of spectral components in thefemtosecond pulse laser. Due to the group delay dispersion and angular dispersion ofTVBG, spatio-temporal distortions can be introduced when femtosecond pulse lasertransmits through TVBG. The temporal and spatial diffraction properties of femtosecondpulse laser through the TVBG are studied in this thesis, and the results have potentialapplications in broadband near-field filtering for ultrashort pulse lasers.The time-domain properties of femtosecond pulse laser diffracted by TVBG is studiedwith Kogelnik’s coupled-wave theory. The properties of Bragg selectivity and group delaydispersion of TVBG are discussed. The influence of spectrum clipping and group delaydispersion on the intensity distribution of diffraction beam in time-domain is studied.Results show that the stretching of diffraction pulse in time-domain results from thespectrum clipping in the case of input pulse duration of100fs, and the strecthing isinfluenced by spectrum clipping and group delay dispersion at the input pulse duration of20fs and10fs.Besides, the spatial property of femtosecond pulse laser diffracted by TVBG isdiscussed. The angular dispersion of TVBG and spatial chirp in the diffraction pulse arediscussed. For the pulse width of100fs and70fs, the rate of spatial broadening through theTVBG is presented. Results show that the beam diameter of the diffraction pulse increaseswith increasing of the propagation distance. The rate of spatial broadening increases withincreasing of the diffracted spectrum bandwidth. |
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