Analysis of dielectric waveguide bends and curved coupler structures using finite difference beam propagation method

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent Univ., 1997.Thesis (Master's) -- -Bilkent University, 1997.Includes bibliographical references leaves 49-52In this thesis, implicit finite difference beam propagation method based on Crank Nicholson discretization procedure is implemented and applied to the analysis of propagation of optical beams in an orthogonal bend and a curved coupler structure. The efficiency factor which accounts for the power loss as a result of the bend is calculated for different waveguide width values and compiired with analytic solutions in the analysis of the orthogonal bend. Also, the effect of the rotation of the etched semiconductor-air interface from its ideal position is examined. In the curved coupler analysis, the bend loss and the variation of lower transfer ratios for different values of minimum distance that separates the branches of the structure are investigated and compared with analytic solutions. On both structure, the evolution of the Gaussian beam in the positive ^-direction is obtained.Ofli, ErdemM.S

Analysis and design of cross-coupled, folded e-plane filters with asymmetric responses

Cross-coupled folded metal insert filters with asymmetric responses are introduced. The selectivity of these filters is further improved by exploiting the source-load coupling to generate up to n finite transmission zeros for a filter of order n. Two 4 th order filters with 2 and 5 finite transmission zeros, respectively are presented to demonstrate the significantly improved response of these filters over their conventional counter part