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合作的。它解决了低维半导体结构对亚皮秒形光脉冲的响应。特别是，我们将使用定制的光脉冲入射到半导体光学微腔上，相干地激发一群激子，然后在亚皮秒的时间尺度上去激发它们。我们将重点关注由于在100 GHz重复频率下控制激子种群而导致的系统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形状光脉冲，在存在和不存在额外的外部强电磁场的情况下，在量子阱中产生可调谐的太赫兹电磁波。太赫兹波形的控制将利用光激发电子空穴波包的相干控制和动力学思想来实现。这是华盛顿州立大学的理论物理学家D.西特林和密歇根大学的实验物理学家T.诺里斯的一项新合作。持续时间极短的激光脉冲将用于控制微观半导体结构中电子的行为。这个新项目将从一个基本的观点出发，研究这种短脉冲如何在小半导体中传播，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极短激光脉冲照射下半导体响应的极限之外，该项目的结果将有助于确定半导体中的快速过程，这些过程可能用于基于光纤的通信系统的下一代超高速光开关。其他预期的应用将是在目前没有或很少存在方便的电磁辐射源的频谱区域中创造新的电磁辐射源。* * *

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. ***