Abstract: Interest in nonlinear optical (NLO) materials for mid-infrared frequency conversion has exploded in recent years due to the emergence of new ultrafast laser applications ranging from frequency-comb-based spectroscopy to high harmonic generation. Advances in growth of the birefringent crystals ZnGeP2 and CdSiP2, as well as all-epitaxial processing of orientation-patterned semiconductors GaAs (OP-GaAs) and GaP (OP-GaP), are extending solid-state laser output deep into the mid-infrared. These materials – developed at BAE Systems - exhibit the highest nonlinear coefficients among all practical NLO crystals. In addition, I am developing crystal growth and processing of a new class of NLO materials – BaGa4S7 (BGS), BaGa4Se7 (BGSe), and BaGa2GeSe6 (BGGSe) - which exhibit lower nonlinearity but offer wider band gaps to enable near-infrared laser pumping, increased laser damage thresholds, and high transparency to even longer infrared wavelengths (> 12 mm), and the possibility of scaling to very large apertures. Finally, I will briefly mention some new NLO crystals in the pipeline designed for more efficient generation in the longwave infrared.
About the Speaker: Peter Schunemann is a leading researcher in developing mid-infrared nonlinear optical (NLO) crystals, authoring or co-authoring over 550 publications and 9 patents in the field. He has BS and MS degrees in Materials Science and Engineering from the Massachusetts Institute of Technology (MIT) and a Doctor of Engineering from Heriot-Watt University. He joined BAE Systems in 1987, where he developed growth & processing of a new NLO crystal - ZnGeP2 - needed for frequency-shifting solid state lasers into the mid-IR. This technology was vital for laser-based IR countermeasure systems which protect aircraft from heat-seeking missiles, earning him the highest corporate technical awards from Sanders and Lockheed Martin. He has since developed or greatly advanced many new NLO materials including AgGaSe2, CdGeAs2, CdSiP2, OP-GaAs, OP-GaP, offering the highest efficiencies and broadest spectral coverage. He is a Fellow of SPIE & Optica (OSA), and past president of the American Association of Crystal Growth.
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