The photorefractive effect in III-V semiconductor multiple quantum well structures
Abstract
The motivation of this work is to combine the large transverse electro-optic nonlinearity with the high charge-carrier mobility within a photorefractive multiple quantum well structure. Photorefractive AlGaAs/GaAs multiple quantum well structures have been studied systematically. Strong diffraction signals from the first, second, and third harmonics of the photorefractive grating were observed. In the two wave mixing study, we found a large photorefractive phase shift that occurs at a field neither in the diffusion field limit nor in the space-charge limit. To understand the origin of the photorefractive phase shift, we have included the effect of the hot-electron transport nonlinearity in the photorefractive transport equations, which provides a successful explanation of observed phenomena. For the first time, the importance of transport nonlinearity in the photorefractive effect is realized, which may force a reinterpretation of apparent trap-limited behavior in photorefractive semiconductors. Similar studies were also performed in a photorefractive InGaAs/GaAs multiple quantum well structure without removing the GaAs substrate. Two-wave mixing and four-wave mixing were observed within the hybrid structure.
Degree
Ph.D.
Advisors
Nolte, Purdue University.
Subject Area
Condensation|Optics
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