Effect of misalignment of grating pair grooves on temporal profiles of chirped-pulse

The effect of misalignment of grating grooves on the output pulse width and temporal profiles was numerically simulated with ray-tracing method and Runge-Kutta method.When the angle of grating grooves is within the range of士4°,the pulse width induced by the original chirp becomes narrower if only considering group delay dispersion(GDD).However,the pulse width becomes broader than that of seed pulse when considering third order dispersion (TOD) or fourth order dispersion (FOD),even higher order dispersion.When the input pulse is with positive chirp,the pule width increases with the angle a continuously.However,when the input pulse is with negative chirp,the pulse width increases with the angle a first,and then decreases.The change of the pulse width is the same with grating G2 revolving clockwise or anti-clockwise.Furthermore,the original chirp makes the pre-pulse and post-pulse weaker.The effect of the negative chirp on pulse width and distortion is much weaker than that of the positive chirn.