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, nearly-stoichiometric, 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. Prepared in cooperation with Coherent Technologies, Inc., Louisville, CO.