Photorefractive non-linear single beam propagation in LiNbO3 waveguides above the optical damage threshold

The effect of photorefractive optical damage on single laser beams in undoped LiNbO3 waveguides has been thoroughly investigated. The experiments have been carried out in soft proton exchanged planar LiNbO3 waveguides covering a wide range of intensities (10–5000 W/cm2). Different non-linear behaviours such as self-defocusing, beam break-up and temporal instabilities have been observed as the light intensity increases. X- and Z-cuts have been compared showing similar behaviours at low intensities although at higher intensities they present relevant differences. Some comments on the influence of these results in LiNbO3 devices have been also included.