Photorefractive Effect in Annealed Proton-Exchanged LiTa03 Waveguides

Quantitative measurements of the photorefractive effect in annealed proton-exchanged (APE) LiTaO3 waveguides have been measured for the first time. In particular, photorefractive measurements at 488 nm in waveguides fabricated on both surface acoustic wave (SAW) grade and optical grade LiTaO3, substrates are reported and compared with that in optical grade APE LiNbO. The results show that while the dark conductivity and the saturated refractive index change of both APE LiTaO3, samples remain the same at very high irradiation levels, the photoconductivity of the SAW grade is much higher than that of the optical grade. The large photorefractive charge may be due primarily to increased absorption by Fe2+ impurityions. Furthermore, as expected, optical grade APE LiTaO, exhibits a smaller photorefractive effect than that of LiNbO, at high intensities.