Optical waveguiding in graded-index layers

Abstract

We use the wave equation and WKB approximate solutions to study the general properties of modes in a waveguide whose index of refraction decreases monotonically with distance below its surface, due to variation of either ionic or electronic contributions. The modes are found to have oscillations that increase in amplitude and in spacing with increasing depth. For modes with smaller propagation constants the oscillatory regions, as well as the decaying regions, are found to penetrate more deeply.