Wavelength and temperature dependence of photorefractive effect in quasi-phase-matched LiNbO3 waveguides

The photorefractive effect (PRE) in quasi-phase-matched LiNbO3 waveguides is studied systematically by employing the pump-probe technique. It is found that the PRE is gradually eased with an increase of the device operation temperature. With increasing light irradiation power, the PRE becomes severe, the buildup (relaxation) time constant decreases (increases), while the second harmonic generation (SHG) efficiency is enhanced for the devices used in studies. The PRE under a shorter wavelength (980nm) light irradiation is much stronger than that at a longer wavelength one (1550nm), and the PRE for the latter is mainly caused by the SHG of the pump.