T. WongcharoenB. M Azizur RahmanKenneth Thomas V GrattanIEEECity University LondonSilpakorn UniversityMahidol UniversityBangkok UniversityOptical Society of AmericaBangladesh University of Engineering and TechnologyUCLInstitution of Electrical EngineersEuropean Optical Society2018-07-042018-07-041997-02-01Journal of Lightwave Technology. Vol.15, No.2 (1997), 377-382073387242-s2.0-0031078902https://repository.li.mahidol.ac.th/handle/20.500.14594/17951Results are presented on a study of the important parameters of synchronous and nonsynchronous, weakly and strongly coupled optical directional couplers using the finite element method. Accurate propagation constants and field profiles have been obtained for the modes of the isolated guides and the supermodes of the coupled system. The power transfer efficiency between nonidentical coupled optical waveguides has been calculated using the coupled mode, the least squares boundary residual and the finite element-based propagation methods. To show the advantages of the finite element-based approaches, the power transfer efficiency between coupled waveguides with two-dimensional confinement is presented.Mahidol UniversityEngineeringPhysics and AstronomyArticleSCOPUS10.1109/50.554391