Propagation in Imperfect Waveguides

Abstract

In a perfect waveguide the power associated with a particular mode remains constant as the beam propagates through the waveguide; we are, of course, neglecting the losses due to absorption. However, in general, there are imperfections in the waveguide; an important example of this is the irregular interface between the core and cladding or a weak z dependence of the dielectric constant. Such imperfections lead to transfer of power between the various modes of the waveguide and the power transferred to the radiation modes results in an exponential decay of the power.