RAY-OPTICAL ANALYSIS OF REFLECTION IN AN OPEN-ENDED PARALLEL-PLANE WAVEGUIDE .1. TM CASE

The reflection problem for a TM mode traveling toward the open end of a semi-infinite parallel-plane waveguide is solved by ray methods. The present ray-optical solution is a rigorous asymptotic result, i. e. , it is identical with the asymptotic expansion of the exact solution when the width of the waveguide is large compared to the wavelength. Numerical results for the modal reflection coefficients are presented and are compared with calculations based on the exact solution. It is found that the agreement between ray-optical and exact values is excellent.