Periodically-Poled, Damage-Resistant Optical Materials

The Air Force needs non-linear optical crystals which can efficiently convert radiation at the wavelengths of solid-state lasers into radiation at other wavelengths. Existing materials which have the desired non-linear conversion efficiency haveshortcomings, including vulnerability to optical damage and limited ultraviolet transparency. Recently a promising new material with superior damage resistance and ultraviolet transparency, stoichiometric lithium tantalate, has become commerciallyavailable. Wafers of this material have shown good non-linear conversion efficiency when patterned appropriately. Our innovation is the production of patterned stoichiometric lithium tantalate using commercially practicable techniques which have alreadyled to one successful product, periodically poled lithium niobate. The result will be a commercial product which meets Air Force requirements for conversion efficiency, damage resistance, and transparency. During Phase I we proved feasibility by showingthat our patterning techniques are effective on commercially available substrates. In Phase II we will prove practicality by decreasing the size of the patterned features, increasing the thickness of the patterned wafers, and measuring the non-linearoptical performance of the resulting optical chips when pumped with high-average power solid-state lasers. At the same time, we will work with a commercial partner, Deltronic Crystal Industries, to establish the necessary crystal-growth facilities.