Generation of Visible Radiation in Periodically Poled, Nearly-Stoichiometric Lithium Tantalate

Stoichiometric lithium tantalate (SLT) has been identified as a promising alternative to congruent lithium niobate as substrate material for quasi-phasematched (QPM) nonlinear optical frequency conversion. The advantages of SLT include superior resistance to optical damage, greater ultraviolet transparency, and a lower coercive field which should facilitate the fabrication of thicker periodically poled chips. We report the generation of 16 W of average power at 589 nm by single-pass sum-frequency generation of two Nd:YAG lasers in undoped, nearlystoichiometric, lithium tantalate. Material which is grown directly from the melt, and which is not doped, therefore has the potential to be useful in applications (such as laser guide-star generation for adaptive optics, or projection displays) which require powers of 10 to 20 W in the visible.