Mutual Control of Carriers and Light in Low-Dimensional Semiconductor Structures

9705403 Citrin这个新项目是华盛顿州的D.Citrin和密歇根大学的T.Norris合作完成的。它解决了低维半导体结构对亚皮秒形状光脉冲的响应。特别是，我们将使用定制的入射到半导体光学微腔上的光脉冲来相干地激发一组激子，然后在亚皮秒的时间尺度上去激发它们。我们将集中讨论由于100 GHz重复频率下激子布居的控制而对系统的光学非线性的超快调制。此外，在这个项目中，我们将探索在半导体中使用赋形光脉冲，在存在和不存在附加外部强电磁场的情况下，在量子井中产生可调谐的太赫兹电磁波形。利用相干控制和光激发电子空穴波包的动力学思想，可以实现对太赫兹波形的控制。这是华盛顿州的理论家D.Citrin和密歇根大学的实验学家T.Norris的新合作。极短持续时间的激光脉冲将被用来控制微观半导体结构中电子的行为。这个新的项目将从根本上解决这种短脉冲如何在小型半导体中传播，以及电子如何对这些光脉冲的通过做出反应。除了有助于我们理解半导体在极短激光脉冲照射下的响应极限之外，该项目的结果还将有助于识别半导体中可能被用于基于光纤的通信系统的下一代超高速光开关的快速工艺。其他预期的应用将是在目前不存在或很少存在方便源的频谱区域中创建新的电磁辐射源。***

9705403 Citrin This new project is a collaboration between D. Citrin at Washington State and T. Norris at the University of Michigan. It addresses the response of low-dimensional semiconductor structures to sub-picosecond shaped optical pulses. In particular, we will employ tailored optical pulses incident on semiconductor optical microcavities to coherently excite a population of excitons, and then de-excite them on the subpicosecond time scale. We will focus on the ultrafast modulation of the optical nonlinearities of the system due to the control of the exciton population at 100 GHz repetition rates. In addition, in this project we will explore the use of shaped optical pulses in semiconductors to generate tunable terahertz electromagnetic waveforms in quantum wells in the presence and absence of additional externally applied strong electromagnetic fields. Control of the THz waveforms ill be attained using ideas from coherent control and dynamics of optically excited electron-hole wavepackets. %%% This is a new collaboration between D. Citrin, a theorist at Washington State and an experimentalist, T. Norris at the University of Michigan. Laser pulses of extremely short duration will be used to control the behavior of electrons in microscopic semiconductor-based structures. This new project will address, from a fundamental viewpoint, how such short pulses propagate through small semiconductors, and how the electrons respond to the passage of these light pulses. In addition to the contribution to our understanding of the ultimate limits to the response of semiconductors illuminated by very short laser pulses, the results of this project will be useful to identify fast processes in semiconductors that may be employed for the next generation of ultrahigh- speed optical switches for optical-fiber-based communications systems. Other expec ted applications will be in creating new sources of electromagnetic radiation in regions of the spectrum where no or few convenient sources presently exist. ***