Modal characteristics of graded multilayer optical waveguides

The modal characteristics of graded-step index multilayer planar waveguides for layer thicknesses down to those applicable for quantum well structures have been investigated here. The effects of linear grading of the transverse stepped refractive index profile have been evaluated in terms of the mode field profiles and the modal spectrum. The position of the maximum of the fundamental mode field profile can be moved toward the upper waveguide cladding/core interface with consequential increase in the evanescent field magnitudes.