TRANSPARENT BOUNDARY-CONDITIONS FOR BEAM-PROPAGATION ANALYSIS FROM THE GREEN-FUNCTION METHOD

Exact formulas that give boundary conditions that simulate an infinite medium in finite-difference-based beam-propagation analysis are found by a Green's function technique and are demonstrated with examples. Comparisons are made between the exact methods derived from the Green's function technique developed in this paper and the approximate methods developed by Hadley [Opt. Lett. 16, 624 (1991); IEEE J. Quantum Electron. 28, 363 (1992)]. The Green's function concept is used in the development of general suggestions that can be applied to the transparent boundary conditions for other beam propagation algorithms.