An accurate variational analysis of single-mode diffused channel waveguides

We present a procedure based on the variational principle to obtain the modal propagation characteristics of single-mode diffused channel waveguides with arbitrary index profiles. The only assumption in our method, in addition to the scalar approximation, is that the trial field is separable along the depth and the width directions. The method is iterative, with each cycle of iteration requiring the solution of two planar waveguide propagation problems. The convergence is usually achieved within 2–3 cycles of iteration. Comparisons with other methods show that our method gives much better accuracy.