Application of the WKB method in determination of the refractive-index profile of planar diffused waveguides

An analysis is made of the potentialities of the quasiclassical approximation and a method is proposed for the determination of the refractive index profile directly from experimental values of the effective refractive indices of multimode planar waveguides formed by diffusion. The method proposed is used to determine the refractive index profile of waveguides formed by the diffusion of titanium into a lithium niobate substrate.