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All-optical generation and coherent control of ultrafast shift and injection currents in GaAs quantum well structures

GaAs量子阱结构中超快位移和注入电流的全光产生和相干控制

基本信息

批准号：
71472506
负责人：
Dr.-Ing. Mark Bieler
金额：
--
依托单位：
Physikalisch-Technische Bundesanstalt (PTB)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2008
资助国家：
德国
起止时间：
2007-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/71472506?language=en
关键词：
optical generation coherent control ultrafast

项目摘要

Generating electrical currents in semiconductors by purely optical means, i.e., without electrical bias fields, using femtosecond laser excitation has not only become a powerful means for studying nonlinear coherent light-matter interaction but also opens promising options for THz electromagnetic wave generation. Different physical processes, like optical rectification, shift current generation, and injection current generation, have been identified as the sources for optically-induced currents. All these effects represent coherent second-order nonlinear optical interactions. While the generation of injection currents is symmetry forbidden in bulk GaAs, we have recently demonstrated that in especially designed, i.e., (110)-oriented, GaAs/AlGaAs quantum well structures injection currents can be generated. Even more surprising and unexpected was our finding that injection currents could be measured for resonant excitation of the lowest exciton resonances. The overall goal of this proposal is to analyze experimentally and theoretically the conditions under which the generation of different types of injection currents by resonant exciton excitation is possible. A sound microscopic theoretical description of the so far not identified underlying physical processes, that is based on extended semiconductor Bloch equations, will be developed and analyzed. Our joint investigations will provide new insight in the fundamental mechanisms governing nonlinear light-matter interactions and all-optical current generation in semiconductor nanostructures.

通过纯光学手段在半导体中产生电流，即，在没有偏置电场的情况下，利用飞秒激光激发不仅成为研究非线性相干光-物质相互作用的有力手段，而且为太赫兹电磁波的产生开辟了一条新的途径。不同的物理过程，如光整流，移位电流的产生，和注入电流的产生，已被确定为光感应电流的来源。所有这些效应都代表了相干的二阶非线性光学相互作用。虽然注入电流的产生在体相GaAs中是对称禁止的，但我们最近证明，在特别设计的情况下，即，可以产生（110）取向的GaAs/AlGaAs量子阱结构注入电流。更令人惊讶和意想不到的是，我们发现，注入电流可以测量最低激子共振的共振激发。本提案的总体目标是从实验和理论上分析共振激子激发产生不同类型注入电流的条件。一个健全的微观理论描述，到目前为止还没有确定的基本物理过程，这是基于扩展的半导体布洛赫方程，将开发和分析。我们的联合研究将为半导体纳米结构中非线性光-物质相互作用和全光学电流产生的基本机制提供新的见解。