Designing diffractive optical elements with subwavelength features as an uniform beam shaper

Abstract

An aperiodic two-dimensional diffractive optical element (DOE) with subwavelength features as an uniform beam shaper which shapes an input laser beam into an uniform intensity distribution in an observation plane has been designed. A rigorous design method combined an iterative optimization algorithm with a rigorous electromagnetic computation -- the finite-difference time-domain (FDTD) method has been proposed. The design method and the FDTD method have been discussed in detail. The simulated results have shown that the DOE designed by this rigorous method can produce an uniform field distribution with flat-top, steep edge and low profile error in an observation plane.