Syntesis of bynary microoptics by gradient method of optimization

We apply a gradient method as synthesis algorithm to the two-dimensional hybrid finite element-boundary element method as vector model of diffraction for the design of DOEs. The hybrid method is capable of modeling inhomogeneous DOEs in unbounded freespace in computationally efficient manner. In this paper we discuss the application of gradient method of optimization to matrix notation of hybrid method. In such application it is possible to analyze profiles with large number of features. This allows to overcome the limitations of time of calculation dependent on amount of modifications of DOE. We use the gradient method to design of binary-phase lenses that has subwavelength features. Although we have considered only binary-phase lenses, presented gradient method is capable of design inhomogeneous DOEs or coatings.