Influence of the Geometrical Configuration on Optical Damage of LiNbO3 Planar Waveguides

Geometrical effects on the optical damage in proton exchanged LiNbO3 waveguides are analyzed. Light intensity thresholds and beam profiles at different intensities have been measured for guides prepared on z- and x-cuts. z-cut alpha-phase proton exchanged guides show a threshold intensity of the same order of magnitude but slightly greater than x-cut. The more important differences between both guides cuts are a clear asymmetry of beam-profile in x-cut guides as opposite to z-cut and the existence of a chaotic evolution at high intensities only found in x-cut guides. The influence of the proton-exchange time on optical damage threshold has been also investigated in z-cut waveguides to compare them with recent reported data on x-cut guides.