This Small Business Innovation Research Phase I project will investigate materials and techniques for ultraviolet (UV) wavelength generation. The material periodically poled lithium tantalate (PPLT) will be used in the range 300-400 nm, and reduction of the absorption near its UV band edge will be investigated to obtain wavelengths <300 nm. For deeper UV periodic twinning of quartz will be investigated. With this material, frequency conversion of Nd: YAG lasers through the sixth harmonic at 177 nm is possible. Together these patterned materials to the important but difficult UV range. The long-range goal is to develop sources operating in the spectral range <400 nm. Low power devices ~10 mW are suitable for some applications; however, the goal is to develop output powers of 100 mW - 1 W. To this end, two approaches will be pursued: improve the basic material and develop device configurations that extend the power range of current materials. Treatments of PPLT to lower its absorption will be studied. Double-pass second harmonic generation by using quasi-phase-matching to properly phase the multiple passes will also be demonstrated. The solid-state UV laser sources being developed in this program will lead to applications in sensors, biomedical instrumentation, stereolithography, semiconductor equipment manufacturing, and photochemistry. The combination of cw-diode-pumped lasers and periodically patterned materials will form a robust and efficient commercial product. As a first step down the path of commercialization, a pulsed tunable visible/UV source will be demonstrated on this program.
