Analysis of Planar Graded-Index Optical Waveguides with Strong Asymmetry of a Refractive Index Profile by the Beam Propagation Method

In the paper application of the beam propagation method (BPM) to investigation of wave processes in regular and nonregular graded-index waveguide structures with strongly asymmetric refractive index profile is analyzed. On purpose to match the BPM requirement to smoothness of the refractive index profile, the profile with strong asymmetry, at the problem solution, is approximately exchanged by a symmetrical one. For exponential and Gaussian profiles of the refractive index the BPM calculations are compared to the strict and WKB solution respectively. Calculation of a wave pattern of a mode field coupling into the substrate at the tapered edge of a waveguide with strongly asymmetric profile is demonstrated.

graded-index optical waveguide, beam propagation method