Femtosecond Optics of Quantum Confined Materials and Devices

本项目旨在对量子受限半导体光学非线性的基本理解和高速全光器件的演示。该计划将研究的材料是硒化镉和硫化镉量子点以及GaAs - A1GaAs多量子阱。研究人员所说的量子点是指嵌入在玻璃基质中的半导体微晶体，其尺寸与激子玻尔半径相当或更小，尺寸分布更均匀。他们将彻底研究这些量子点中光学非线性的大小和响应时间，并将这些量与它们的体积值进行比较，这将使他们能够确定量子点中的量子限制是否会导致材料非线性或速度的增强。由激子光学Stark效应引起的瞬时非线性将用于演示GaAs MQW定向耦合器中的高速开关。最后，他们将尝试使用虚拟载波激励产生亚皮秒电脉冲，然后使用这些超短电脉冲通过量子受限斯塔克效应在MQW非线性定向耦合器中获得亚皮秒开关。

This project is directed towards basic understanding of quantum confined semiconductor optical nonlinearities and demonstration of high-speed all-optical devices. The materials that will be investigated under this program are Cadmium Selenide and Cadmium Sulfide quantum dots and GaAs - A1GaAs multiple quantum wells. By quantum dots, the investigators mean microcrystals of semiconductor embedded in glass matrices with sizes that are comparable or smaller than the exciton Bohr radius with a more uniform size distribution. They will investigate thoroughly the magnitude and response time of optical nonlinearity in these quantum dots and compare these quantities with their bulk values, will enable them to determine whether quantum confinement in the dots results in enhancement of the nonlinearity or speed of the material. The instantaneous nonlinearity arising from exciton optical Stark effect will be employed to demonstrate high-speed switching in a GaAs MQW directional coupler. Finally, they will attempt to generate subpicosecond electrical pulses using virtual carrier excitation, and then use these ultrashort electrical pulses to obtain subpicosecond switching in a MQW nonlinear directional coupler via the quantum confined Stark effect.