Experimental determination of the effective thickness of diffused waveguides

A description is given of a simple method for determining the effective thickness of diffused waveguides with an arbitrary refractive index distribution n (x). The measured effective waveguide thickness is governed by the mode field at the boundary. Experimental determinations of the effective thickness are reported for waveguides in glass formed by the diffusion of Ag⁺ and the various methods for finding the effective thickness of diffused waveguides are compared.