Extension and Optimization of the Axisymmetric 2.5-D Eigensolver: Toward Far-Field Calculations in Stratified Backgrounds

Abstract

We extend and optimize the axisymmetric 2.5-D eigensolver to calculate the far-field results of axisymmetric structures in stratified backgrounds (SBs), which is useful and practical for optical design and engineering. Two kinds of near-field-to-farfield transformations (NFFFTs) are proposed. One is called closedsurface transformation which is based on the dipole radiations in SBs. The other is called open-surface transformation which is based on the analytic continuation. This transformation can provide the far-field results of any axisymmetric structure (including backgrounds). The far-field results achieved by these two transformations are in good agreement with each other and with analytical ones. Moreover, in order to obtain accurate near-field results, we optimize the perfectly matched layer (PML) setting of the 2.5-D eigensolver. Corresponding optimization rules are proposed and discussed.