Saswatee BANERJEE, James B. COLE¹ and Toyohiko YATAGAI^*

Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
¹Department of Systems and Information Engineering, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan

(Received October 1, 2004; Accepted May 29, 2005)

Gratings with subwavelength groove depth and period are frequently used in optics for various purposes. The polarization dependent diffraction characteristics of subwavelength (high frequency) gratings can only be calculated by solving Maxwell's equations of electromagnetism. In this paper, we calculate the classical diffraction characteristics of subwavelength conducting gratings numerically, using a new high accuracy version of nonstandard finite-difference time-domain (NS-FDTD) algorithm. For the purpose of analysis, we employ a gold sinusoidal grating with light incident at a large angle. We have compared high accuracy NS-FDTD simulation results with those obtained from standard finite-difference time-domain (S-FDTD), and the finite element method (FEM) simulations.

Key words: grating diffraction, subwavelength diffractive optical elements, conducting gratings, microoptics, electromagnetic theory, finite-difference time-domain method

^*E-mail address: yatagai@bk.tsukuba.ac.jp