DESIGN OF 2-D QUASI-OPTICAL BEAM SPLITTERS USING ANALYTICAL GRADIENTS

Quasi-optical systems comprised of diffractive phase elements (DPEs) are designed as beam splitters. The design tasks are reformulated as optimization problems in which target functionals are defined. Analytical gradients are derived to those functionals, which can be passed to gradient methods to efficiently determine the DPEs. Rayleigh-Sommerfeld diffraction integrals are applied to compute the wave propagation in free-space between parallel planes in the quasi-optical systems. Numerical results for several beam splitters are depicted. Furthermore a procedure is proposed, how the phase functions of the DPEs could be smoothed out.