High-efficiency binary phase-transmission-grating using e-beam lithography

Rigorous coupled-wave analysis indicates that diffraction efficiencies greater than 99% are feasible for dielectric phase-gratings with a rectangular profile. The use of rectangular rather than blazed profiles implies simplified fabrication techniques, since deep-etch submicrometre structuring techniques can be utilized. We identify several parameter combinations with high diffraction efficiencies using rigorous coupled wave analysis, demonstrate experimentally diffraction efficiencies of 94% in a Bragg mount configuration at a wavelength of 543 nm and discuss the influence of substrate thickness on the transmitted light intensities. A direct writing electron-beam lithography fabrication process gives wide flexibility in design realization.