Abstract

Diffraction gratings operating in the Raman-Nath diffraction regime (i.e., thin structures) have generally multiple diffracted output waves for a single incident wave. The distribution of energy among the diffracted waves is found to be critically dependent on the grating shape. This applies to both bulk-modulated (or planar) gratings and surface-modulated (or surface-relief) structures. For some applications, it is of interest to produce structures with multiple diffracted waves of approximately equal intensities. A particularly simple approach to achieve this is to use periodic structures consisting of arrays of dielectric cylinders. Our purpose is to present a simple theory to describe the diffraction behavior of periodic dielectric cylindrical arrays. Integral expressions are given for the complex amplitudes of the diffracted waves. A simple approximate formula for the diffraction efficiency of the zeroth order is presented. The model is evaluated experimentally, and good agreement is found. The diffraction regime in which multiple diffracted waves with similar intensities exist is defined quantitatively via a single parameter.

© 1988 Optical Society of America