PERFECT BLAZING FOR TRANSMISSION GRATINGS - GENERALIZATION AND NUMERICAL VERIFICATION

A preceding paper [J. Opt. Sec. Am. A 7, 1736 (1990)] demonstrated an interesting property of perfect blazing in transmission for triangular -groove dielectric gratings. The grating was obtained by evaporating a n infinitely thin lager of perfectly conducting metal on the small fac et of the groove. if an antireflection coating is deposited on top of the large facet, the electromagnetic theory is able to predict an effi ciency of 100% in trans mission. Our purpose is first to generalize th is blazing property to gratings with inhomogeneous index and then to g ive a numerical confirmation of these theoretical predictions using a computer code based on a rigorous finite-clement method [J. Opt. Sec. Am. A 10, 2592 (1993)]. The precision of this numerical verification i s quite good. The curves of efficiency near the blazing effect show re markable widths in wavelength and incidence. (C) 1996 Optical Society of America.