Lithium Borogermanate; A New NLO Crystal for Frequency Conversion

Nonlinear optical (NLO) materials play a critical role in current solid-state laser systems enabling broad tunability and operation at wavelengths not accessible by available laser gain media. At the same time, NLO materials limit the longevity and efficiency of these laser systems due to low damage thresholds, poor optical quality and small nonlinearities. As a result, new NLO materials are required to improve the performance of existing systems and to provide new combinations of optical and mechanical properties that yield new wavelengths. Specifically, there is a need for new/better NLO materials for use in high efficiency all solid-state lasers operating in the UV. Borate crystals, including BBO and LBO, are currently two of the industry standards for this application. A new material, lithium borogermanate (LBG), has the potential to replace these materials with increased transmission in the UV combined with larger nonlinearities. Based on preliminary characterization results, crystalline structure, and composition, LBG has the potential to enable new devices that require operation deeper in the UV. This Phase I SBIR project is aimed at developing hydrothermal growth systems for this new NLO material. This project will use unique, resealable, hydrothermal growth equipment capable of precise control and in-situ monitoring of growth conditions.