Design of subwavelength diffractive optical elements using a hybrid finite element-boundary element method

We present an algorithm for the design of 1D binary-phase subwavelength lenses that uses a hybrid finite element-boundary element method to model vector diffraction and a simulated quenching routine to perform the optimization. The hybrid method offers several advantages over other analysis techniques in terms of both computational efficiency and storage requirements. To facilitate the rapid convergence of the design, we use two subwavelength lenses, which we designed based on scalar techniques, as initial inputs to the algorithm. The designs produced by both lenses are presented.