Travel Grant: RUI: Engineering of Two-Photon Nonlinearities in Bulk and Artificially Structured Semiconductors

这项拟议的研究将研究不同掺杂和生长技术的块体和薄膜结构中的各种半导体材料中的双光子吸收和相关的自折射。PI将使用美国国家科学基金会资助的ECS 8310625开发的技术和知识来研究新材料。这项由NSF赞助的工作表明，只需几个材料参数，就可以预测非掺杂块体半导体的双光子吸收系数在50%以内。关于杂质和缺陷的影响，问题仍然存在。目前的研究已经导致了非掺杂块体半导体中双光子吸收的预测模型的发展，以及研究非线性吸收和随后的自散焦的光霍尔技术的发展。通过故意产生缺陷和添加杂质以及使用包括窄带干涉滤光片和多量子阱在内的薄膜结构来设计半导体中的非线性的可能性将被研究。PI将与北得克萨斯州立大学和赫里奥特-瓦特大学的研究人员以及休斯研究实验室、德克萨斯仪器、普渡大学和圣母大学等材料供应商合作。这项研究旨在应用过去美国国家科学基金会资助下发展起来的实验技术和理论理解，对各种半导体材料和薄膜结构中的非线性双光子吸收和相关的自折射进行广泛的研究。这些研究成果将在光学双稳态、光限幅与开关、激光对光学材料的损伤等领域具有广泛的应用前景。几家大学和行业合作者正在为这项研究提供样本。

The proposed research will investigate two-photo absorption and the associated self-refraction in various semiconducting materials in bulk and thin film structures with differeing dopants and growth techniques. The PI's will use the techniques and knowledge developed under NSF grant ECS 8310625 to investigate new materials. This NSF sponsored work showed that the two-photon absorption coefficient in undoped bulk semiconductors could be predicted to within 50% knowing only a few material parameters. Questions still remain about the effects of impurities and defects. Current researach has resulted in the development of a predictive model for two-photon absorption in undoped bulk semiconductors and the development of the photo-Hall technique to investigate nonlinear absorption and subsequent self-defocusing. The possibilities of engineering the nonlinearities in semiconductors by intentionally producing defects and adding impurities as well as using thin-film architectures including narrow-band interference filters and multiple-quantum wells will be investigated. The PI's will collaborate with researchers at North Texas State University and Heriot-Watt University, and with materials suppliers such as Hughes Research Laboratories, Texas Instruments, Purdue University and Notre Dame University. This reserach intends to apply experimental techniques and theoretical understanding developed under past NSF sponsorship to perform an extensive study of nonlinear two-photon absorption and associated self-refraction in a wide variety of semiconducting materials and thin-film structures. The results of these studies should have broad applications to such fields as optical bistability, optical limiting and switching, and laser-induced damage to optical materials. Several university and industrial collaborators are supplying samples for this research.