Investigation of spatio-temporal stretching in a duplex grating compressor.
We employ the modified 6×6 matrix formalism to describe a pulsed Gaussian beam diffracted by a grating with arbitrary orientation. The matrix treatment is used to analyze the evolution of a pulsed beam propagating in a duplex grating compressor (DGC). For chirped pulse incidence, the inclination angle required in DGC setups will introduce several kinds of first-order spatio-temporal couplings (STCs). We found that temporal stretching due to spatial chirp is suppressed with enlarged beam diameter. Pulse-front tilt and residual frequency chirp in the compressed pulse will be eliminated simultaneously. Pulse with the transform-limited duration can be expected in ultra-intense and ultra-short pulse laser systems employing DGC.