Optimization design of an ultrabroadband, high-efficiency, all-dielectric grating.

More than 97% flat-top diffraction efficiency in the -1st-order TE polarization over a 110 nm wavelength range around 800 nm in an all-dielectric grating is designed by a simulated annealing algorithm and the Fourier mode method. Its band is near to the maximum bandwidth provided by a dielectric high-reflectivity mirror under the match layer. This result will provide a way for high-efficiency chirped-pulse amplification to be used in an ultrashort high-power pulse laser system based on all-dielectric gratings. Furthermore, an effective method for broadband high-efficiency all-dielectric grating design is presented in this Letter.