Suppression of beam fanning in near-stoichiometric lithium niobate crystal by ultraviolet light irradiation

A method has been proposed and demonstrated to suppress the beam-fanning effect induced by a green laser beam of 532 nm in near-stoichiometric lithium niobate crystal with an ultraviolet (UV) beam of 350 nm. The beam-fanning effect at different intensities of UV and green beams has been investigated qualitatively and quantitatively. The results show that the beam-fanning effect can be suppressed almost perfectly with the UV light intensity of only about one seventh of the intensity of green light. Suppression of beam fanning is attributed to the large increase of photoconductivity by UV light irradiation.