A refined WKB method for symmetric planar waveguides with truncated-index profiles and graded-index profiles

摘要

An accurate method is proposed, based on a modified version of the WKB method in quantum mechanics, for evaluating the propagation constants and field distribution of symmetric planar waveguides with a truncated-index and graded-index profile. Simple formulas are given for calculating the dispersion characteristics including those for the truncated parabolic and exponential profile, and results are much more accurate than those of the ordinary WKB method, especially in the near cutoff regions. This method also can be extended to other more complicated cases.