Designing diffractive optical elements for special functions using a rigorous method

Abstract

The rapid miniaturization in technologies for signal, image processing and optical communication increases the need for diffractive optical elements (DOEs), whose scales move closer to that of the illumination wavelength. The optical behaviour of DOEs is dependent on the polarization of the incident light, and so it is necessary to use a rigorous electromagnetic theory of diffraction to accurately design and analyse its performance. An iterative optimization algorithm for designing two dimensional, finite aperture, aperiodic diffractive optical elements based on a rigorous electromagnetic computation model—the finite-difference time-domain method—has been introduced. The algorithm can present rigorous design results with reasonable computational cost. Two kinds of DOEs designed by our algorithm, one for realizing the beam deflection used for integration optical systems, etc, and the other for realizing 1-to-2 beam split and 1-to-3 beam split, used for optical interconnections, etc, are presented. The simulated results have shown that our method has advantages of good optimization potential, high convergence and is an attractive approach for the rigorous design of DOEs.