Combined Optical and Terzhertz Control of Semiconductor Nanostructures

本研究项目涉及使用相干光学和太赫兹（THz）场来控制半导体量子结构（包括量子阱和正模微腔）中电子、空穴和激子的相位和数量。相干光脉冲和单周期太赫兹脉冲将由飞秒激光产生。光脉冲和太赫兹脉冲的结合使用为半导体中电子空穴波包的产生和控制开辟了新的可能性。将探讨三个一般的研究领域：(1)微腔的相干控制和量子输运的光学类比；(2)激子波包的太赫兹发射；(3)激子和极化子动力学的太赫兹探测。这些实验将使我们能够探索半导体光学与其他物理领域中非常感兴趣的过程的类比，即量子系统中电子的单粒子输运，以及短强激光脉冲电离原子时产生的高谐波。研究生和本科生以及博士后研究助理将参与本研究。当光照射在半导体材料上时，与材料中的原子紧密结合的电子被“释放”出来，在半导体中移动。如果光激发的波长（颜色）选择得当，这些形成的状态称为“激子”，其行为在许多方面类似于氢原子。在过去的几十年里，人们进行了许多光学实验来研究这些激子的性质。随着飞秒激光技术的出现，不仅可以产生激子，而且还可以控制激子。我们的计划将采用一种新颖的方法来控制激子，通过同时使用光学和远红外（太赫兹频率）脉冲来操纵半导体中的电子。从技术的角度来看，正在研究的基础科学是重要的，因为高速（太赫兹）电子和光学之间的接口是高速通信和计算机进一步发展必须解决的基本问题之一。本研究将由研究生、本科生和博士后合作进行。他们将接受当代前沿科学和技术领域的培训，从而为进入科学/技术劳动力做好准备

This research project concerns the use of coherent optical and terahertz (THz) fields to control the phase and population of electrons, holes, and excitons in semiconductor quantum structures, including quantum wells and normal-mode microcavities. Coherent optical and single-cycle terahertz (THz) pulses will be generated by means of femtosecond lasers. The combined use of optical and THz pulses opens up new possibilities for the generation and control of electron-hole wavepackets in semiconductors. Three general areas of research will be explored: (1) Coherent Control of Microcavities and Optical Analogies to Quantum Transport, (2) THz Emission from Excitonic Wavepackets, and (3) THz probes of Exciton and Polariton Dynamics. These experiments will allow us to explore the semiconductor optical analogies to processes of great interest in other fields of physics, namely single-particle transport of electrons in quantum systems, and the generation of high harmonics in the ionization of atoms by short intense laser pulses. Graduate and undergraduate students as well as post doctoral research associates will participate in this research.%%%When light shines on a semiconductor material, electrons which are tightly bound to the atoms in the material are "freed up" to move throughout the semiconductor. If the wavelength (color) of the optical excitation is chosen properly, these form states called "excitons" which behave in many ways analogously to a hydrogen atom. Over the past few decades, many optical experiments were performed to study the properties of these excitons. With the recent advent of femtosecond laser technology, it has become possible to not only generate excitons, but to control them as well. Our program will take a novel approach to the control of excitons, by using simultaneous optical and far-infrared (terahertz frequency) pulses to manipulate the electrons in the semiconductor. The basic science being investigated is important from a technological point of view, because the interface between high-speed (terahertz) electronics and optics is one of the fundamental problems which must be addressed for the further development of high-speed communications and computers. This research will engage the collaboration of graduate and advanced undergraduate students and post doctoral research associates. They will receive training in a contemporary forefront area of science and technology and thereby prepare them for entry into the scientific/technological workforce.***