DIFFRACTION FROM AN ABRUPTLY TERMINATED SINGLE-MODE FIBER WAVE-GUIDE

Diffraction from an abruptly terminated single mode fiber waveguide is treated analytically. A step index waveguide carrying the fundamental HE11 mode, incident on the abruptly terminated aperture, is assumed. The diffracted fields inside the fiber and free space regions are described in terms of the mixed spectrum vector eigenwaves. In treating the field of the fiber waveguide a full spectrum of guided and radiation modes is employed without making use of the weak guidance approximation. An integral equation is developed on the abruptly terminated fiber waveguide aperture in terms of the unknown aperture electric field. This equation is solved approximately by applying an iterative technique. Numerical results are presented for the reflection coefficient of the HE11 mode and the radiation far field in the free space region.