Abstract

Recently, it has been shown theoretically and experimentally that high-spatial-frequency rectangular-groove (binary) dielectric gratings exhibit zero reflectivity. This means that a high-spatial-frequency periodic surface on a dielectric behaves like an antireflection surface. Thus damage-prone thin-film antireflection coatings can be replaced by a grating directly on the optical element. Antireflection coatings for a substrate where the thin-film refractive index is difficult to synthesize can now be made. In these high-spatial-frequency gratings, the periodicity is less than the light wavelength in the medium. Thus all diffracted orders other than the zero order are evanescent and cut off.

© 1987 Optical Society of America