Dielectric coated gratings: a curious property

Abstract

Theoretical calculations predict that under certain special conditions a shallow fine pitch diffraction grating, given a precise dielectric overcoating, acts as a complete absorber of incident light of a specific wavelength and polarized in the P plane. Despite lack of a physical explanation, the phenomenon was confirmed by experiment.

Electromagnetic resonances in linear and nonlinear optics: phenomenological study of grating behavior through the poles and zeros of the scattering operator

“…A total absorption phenomenon occurs for a suitable dielectric thickness. 15 As soon as the existence of a pole and a zero has been established, including the slow dependence of C͑h͒ on d in Eq. 15, the function B 0 ͑d, h͒ may be written as…”

“…This has been thoroughly confirmed by experiments. 15,16 On other periodic structures such as corrugated waveguides, the pole and the zero may have real parts that significantly differ. The zeroth-order efficiency curve then presents a more complicated shape with both a minimum [corresponding to Re͑d z ͒] and a maximum [corresponding to Re͑d p ͒] (Fig.…”

“…Moreover, the argument developed in Subsection 2.C [see Eqs. (14) and (15)] allows us to predict the existence of three different zeros associated with the zeroth diffracted order at 2v.…”

“…, and the angular dependence is almost completely determined by a single pole ͑d p couple and Eq (15). [crosses inFig.…”

Total absorption of light by a sinusoidal grating near grazing incidence

“…Also, in contrast to Ref. 12, it applies to the S plane only, covers both zero and first orders simultaneously, and involves no dielectric overcoating. This totally unexpected behavior was discovered first in theoretical calculations and later fully confirmed by experiment.…”