Modal profiles in Ti : LiNbO3 two-waveguide and three-waveguide couplers by effective-index-based matrix method

Graded-index optical channel waveguides like Ti-indiffused LiNbO3 waveguide s have been modelled by effective refractive index profile along the latera l direction, discretising the profile and then using the matrix method. Thi s effective-index-based matrix method, which was earlier used to compute th e modal propagation constants of Ti:LiNbO3 channel waveguides and direction al couplers [Fib. Integrat. Opt. 17 (1998) 139] and the bending loss [J. Op t. Commun. 155 (1998) 125], has been established in this paper as a computa tionally fast, analytical method to compute electric field and modal intens ity profiles in single and coupled waveguides. In order to handle coupled w aveguides consisting of three waveguides, the concept of overlap integral h as been used to analyse power coupling to the middle waveguide for applicat ions in power splitting. Some of the computed intensity profiles have been compared with experimental data obtained by the authors. Although computati on has been performed only for TE and TM polarisations, the method has the inherent capability of handling arbitrary polarisation. (C) 2001 Elsevier S cience B.V. All rights reserved.