DIELECTRIC BINARY BLAZED GRATINGS

Artificial index gratings, which are composed of binary microstructure s of sizes less than the incident wavelength, are analyzed as function s of the filling factor or duty cycle of the microstructures. Differen t models for calculating the optimum duty cycles to produce high blaze d diffraction efficiency are compared. Blazed binary grating designs i n a material with a refractive index n = 2 show theoretical diffractio n efficiencies as high as eta = 80%. In the semiconductor material sil icon, which has a refractive index n = 3.4, theoretical diffraction ef ficiencies as high as eta = 70% are predicted.