Dipole radiation into grating structures

We present a detailed electromagnetic analysis for the radiation of an elec tric source located inside grating structures. Our analysis is based on the differential method and uses the scattering-matrix algorithm. We show that gratings that exhibit periodic modulations along two spatial directions (c rossed gratings) enable one to couple out the totality of the light emitted by the source into the guided modes of the structure. This property is inv estigated through the computation of the far-field radiation patterns for c rossed gratings with various etching depths. One key result is the possibil ity to confine the emitted light in a direction about the sample normal, a property that is of interest in the context of spontaneous emission control by microcavity structures. (C) 2000 Optical Society of America [S0740-3232 (00)01506-4].