All-dielectric High-efficiency Reflection Gratings Made with Multilayer Thin-film Coatings

It is well known that a high reflectivity mirror can be made by coating multiple pairs of dielectric thin films of high refractive index contrast and quarter wave optical thickness onto an optically flat surface. The advantages of a multilayer dielectric mirror over a metallic first surface mirror include high reflectivity, low absorption, and therefore high optical damage threshold. In connection to diffraction gratings, one may naturally ask the question: can a high diffraction efficiency grating be made by coating multilayer dielectric thin-films onto a bare surface relief grating? The answer is yes. In this paper, we present the results of our theoretical and experimental investigation.