Total absorption of light by gratings in grazing incidence: a connection in the complex plane with other types of anomaly

Abstract

An explanation is given for the effect of total absorption of light in grazing incidence by a sinusoidal grating, recently reported by us. The behavior of the zeros of both the first and the zeroth diffraction orders is studied numerically in the complex alpha plane. A link between the grating anomaly, non-Littrow perfect blazing, and plasmon excitation in relief metallic gratings is established. A total analysis of the behavior of the zeroth-order zero in grazing incidence is carried out, including groove depth, wavelength, and profile dependences.