Effective medium theory is useful for designing optical elements with a form-birefringent subwavelength structure. We describe a way to determine the effective refractive indices and the directions of their principal axes for two-dimensional (2-D) subwavelength gratings in the normal incidence case. The effective indices and the directions are calculated from finite coupled-coefficient equations that are used in 2-D rigorous coupled-wave analysis. We use the effective medium theory to calculate transmittance of several kinds of 2-D periodic subwavelength gratings. These results are compared with results of rigorous grating analysis to confirm the predictions of the effective medium theory for 2-D subwavelength gratings.
© 1998 Optical Society of America
(050.2770) Diffraction and gratings : Gratings
(160.1190) Materials : Anisotropic optical materials
(230.3990) Optical devices : Micro-optical devices
(230.5440) Optical devices : Polarization-selective devices
Hisao Kikuta, Yasushi Ohira, Hayao Kubo, and Koichi Iwata, "Effective medium theory of two-dimensional subwavelength gratings in the non-quasi-static limit," J. Opt. Soc. Am. A 15, 1577-1585 (1998)