The propagation and coupling phenomena in grating-assisted optical couplers are analyzed by using an integral equation formulation and applying an entire-domain Galerkin technique. The proposed method constitutes a special type of the method of moments and provides high numerical stability and controllable accuracy. The electric field in the grating region is the unknown quantity and the resulting integral equation is subsequently solved by using Galerkin's method. The propagation constants of the guided waves are computed accurately by determining the singular points of the corresponding system's matrix. Numerical results regarding the propagation constants are presented for various coupler parameters, and the effect of the grating's physical and geometric characteristics on the coupling process is investigated.
© 2006 Optical Society of America
Original Manuscript: October 14, 2005
Revised Manuscript: November 28, 2005
Manuscript Accepted: December 1, 2005
Nikolaos L. Tsitsas, Dimitra I. Kaklamani, and Nikolaos K. Uzunoglu, "Integral equation analysis of coupling in symmetric grating-assisted optical waveguides," J. Opt. Soc. Am. A 23, 1488-1502 (2006)