title: Comparison of iterative angular spectrum and optimal rotation angle methods in designing beam-fanners.
abstract: We compare the iterative angular spectrum (IAS) and the optimal rotation angle (ORA) methods in designing two-dimensional finite aperture diffractive optical elements (FADOEs) used as beamfanners. The transfer functions of both methods are compared analytically in the spatial frequency domain. We have designed several structures of 1-to-4 and 1-to-6 beamfanners to investigate the differences in the performance of the beamfanners designed by ORA method for near field operation. Using the three-dimensional finite difference time-domain (3-D FDTD) method with perfect matched layer (PML) absorbing boundary condition (ABC), the diffraction efficiency is calculated for each designed FADOE and the corresponding values are compared.
authors.affiliation: Electrical Engineering Department, Ferdowsi University of Mashhad, Iran. kazemi@ymail.com
authors.forename: Seyyed H
authors.initials: SH
authors.lastname: Kazemi
authors.forename: Mir M
authors.initials: MM
authors.lastname: Mirsalehi
authors.forename: Amir R
authors.initials: AR
authors.lastname: Attari