Experimental validation of simple model for ion-exchanged periodically segmented waveguides

The realisation and characterisation of periodic segmented waveguides made by Ag+/Na+ ion-exchange on glass is presented. In particular, the averaging effects provided by the segmentation are analysed using the measurement of the cutoff wavelengths of the fundamental mode. Numerical calculations are used to evaluate the equivalent index contrast of a continuous waveguide from cutoff wavelength. It is found that the model predicting the index averaging effect of periodically segmented waveguides is valid if the duty cycle of the segmented waveguide is corrected by a term that takes into account the longitudinal ion diffusion.