Broadband and high-efficiency metal-multilayer dielectric grating centered at 800nm based on non-quarter wave coatings as reflective mirror

Abstract

This article deals with designing broadband and high efficiency metal multi-layer dielectric grating (MMDG) used to compress and stretch ultra-short laser pulse. The diffraction characteristics of MMDG are analyzed with the method of rigorous coupled-wave analysis (RCWA). Taking the diffraction efficiency of the -1 order as the value of merit function, the parameters such as groove depth, residual thickness, duty cycle are optimized to obtain broadband and high diffraction efficiency. The optimized MMDG shows an ultra-broadband working spectrum with the average efficiency exceeding 97% over 135nm wavelength centered at 800nm and TE polarization. The optimized MMDG should be useful for chirped pulse amplification.