Design and Properties of Concave Diffraction Gratings Based on Elliptical Bragg Mirrors

Fully dielectric diffraction gratings using Bragg mirrors that can be used in integrated spectrometry or wavelength division multiplexing (WDM) components are presented. Based on extended elliptical Bragg mirrors, they can preferentially select one particular diffraction order. The geometrical design conditions are presented along with numerical simulations for this family of gratings in which diffraction grating and Bragg mirror are not independent, resulting in efficiencies up to 99.9%. High grating efficiency is linked to Bragg mirror efficiency, even though wide Bragg bandwidth can be detrimental to the grating efficiency.