Optimization of power transfer in multiple-waveguide couplers

The eigenvalue equations for a slab multiple-waveguide symmetric coupler were solved for the case in which the coupler has more than three guides. It is shown that equal mode spacing in such an N-guide coupler can be obtained by adjusting the widths and the separations of the guides. The optimum widths and separations were calculated by solving the resulting nonlinear simultaneous equations using the Newton-Raphson method. Maximum power-transfer efficiency from one outermost guide to the other outermost guide was found.<
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