Coupled-Mode Analysis of a Symmetric Nonlinear Directional Coupler Using a Singular Perturbation Scheme

Kiyotoshi YASUMOTO  Naoto MAEKAWA  Hiroshi MAEDA  

IEICE TRANSACTIONS on Electronics   Vol.E77-C    No.11    pp.1771-1775
Publication Date: 1994/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Electromagnetic Theory)
nonlinear directional coupler,  optical switching,  coupled-mode analysis,  

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A coupled-mode analysis of a symmetric planar nonlinear directional coupler (NLDC) is presented by using a singular perturbation scheme. The effects of linear coupling and nonlinear modification of refractive index are treated to be small perturbations, and the modal fields of isolated linear waveguides are employed as the basis of propagation model. The self-consistent first-order coupled-mode equations governing the transfer of optical power along the NLDC are obtained in analytically closed form. It is shown that tha critical power for optical switching derived from the coupled-mode equations is in close agreement with that obtained by the numerical analysis using the finite difference beam propagation mathod.