The effects of material absorption on ray power attenuation in multi-layered optical waveguides

Abstract

A multi-layered graded or step-index optical waveguide of slab or cylindrical geometry and composed of slightly lossy core and cladding materials is regarded as a superposition of separate layers. The ray power loss within each layer can be summed to determine the total power loss and the power attenuation coefficient along the guide. This building-block approach accounts for losses due to both tunnelling and absorption. In general, for practical waveguides, the total loss can be written down by inspection as a combination of six basic terms. Power loss along the ray path, in the neighbourhood of caustics and in the evanescent regions associated with the ray fields are all included in the description.