Variational analysis of modal-coupling efficiency between graded-index waveguides

Some new trial functions that extend the Hermite-Gaussian (HG) function are proposed for solving the modal coupling of one planar graded-index waveguide region to another and with the assumption of no reflections, based on the scalar variational principle. In many cases in this work, we show that the present trial functions give a significant improvement over the HG trial function and are very close to the exact numerical results. Since approximate results in a closed form can be derived by variational approach, this analysis is also very useful in the modal-coupling design of the other integrated-optical devices.<
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