Characterisation of proton-exchanged and annealed proton-exchanged planar waveguides in z-cut LiNbO3

Mode index measurements of planar waveguides fabricated by proton-exchange and annealed proton-exchange in z-cut LiNbO₃ have been made. A Fermi function was found to accurately model the index profile in a PE waveguide resulting in a better agreement between the measured mode indices and the computed dispersion curves compared to the conventional step-index profile. In addition, the effects of various fabrication parameters on the propagation characteristics of single-mode annealed proton-exchange wave-guides have been investigated in detail. Such information will be useful in the analysis, design, and optimisation of devices to be fabricated with the proton-exchange and annealed proton-exchange technology