Three Dimensional Vector-based Analysis of Subwavelength Diffractive Optical Elements using the Finite-Difference-Time-Domain (FDTD) Method

Abstract

Diffractive optical elements (DOEs) whose features are smaller than the wavelength of illumination are referred to as subwavelength diffractive optical elements (SWDOEs). Subwavelength features provide SWDOEs with an added degree of flexibility over their superwavelength counterparts. For example, in the case of binary structures, SWDOEs have been shown to achieve diffraction efficiencies in excess of 90%[1]. This added flexibility, however, results in a significant cost. Namely, the analysis and subsequent design of SWDOEs require the use of rigorous electromagnetic (EM) models. These models, which incorporate the full vector nature of electromagnetic fields, can be theoretically challenging to construct and often demand considerable computational resources.