K-series approximation of vectorial optical model for DOE

an efficient vector diffraction theory to generate macroscopic kinoform with pixels at a subwavelength scale.

This code generates diffractive optical elements (DOE), kinoform, by using k (wave-vector) series approximation of vectorial optical model. The model applies the first-order approximation (r=1 and s=1) in this version.

Relevant algorithms are discussed in the paper Optics Express 29, 37211-37224 (2021), titlted by "K-series approximation of vectorial optical fields for designing diffractive optical elements with subwavelength feature sizes".