Multilayer dielectric gratings for ultrashort pulse compressor

A general method of designing multilayer dielectric (MLD) gratings for ultrashort pulse compressor is presented, which is based on the integration of Fourier spectrum decomposition and rigorous modal method. Numerical calculations show that the shape and energy of the -1st order reflected pulse is greatly dependant on the reflection bandwidth of the MLD grating, which can be greatly improved by etching gratings into a MLD coating with broad reflection bandwidth. In order to improve the damage resistant ability, the average intensity in the MLD grating is used as another criterion to optimize the grating structure. The fabricated MLD gratings provide diffraction efficiencies higher than 95% at Litrrow angle of 51.2 degree for 1053nm short pulse. Damage tests show that 3.5J/cm2 LIDT can be obtained under the irradiation of 12- ns pulse light.