EVALUATION OF REFRACTIVE-INDEX APPROXIMATIONS USED FOR MODE DETERMINATION IN MULTIPLE QUANTUM-WELL SLAB WAVE-GUIDES

Approximations commonly used to determine the effective indexes of the guided modes of optical waveguides formed using multiple quantum well materials are compared to the exact solutions in the slab waveguide model. Modeling the quantum well region as a single homogeneous layer with an average index of refraction is shown to produce results in close agreement with exact values of the effective index. A geometrically weighted average of the indexes provides the most accurate approximation for typical values of index and layer thickness of GaAs-Al(x)Ga(1-x)As quantum well waveguides.