Fundamentals and Applications of Ultra-Slow Light Propagation in Room Temperature Solids

最近的研究已经导致了技术的发展，这种技术可以使光以大大降低（或增加）的群速度通过材料系统传播。 对慢光的兴趣既源于概念问题，也源于其在可控延迟线、信息存储设备和量子信息处理等应用中的潜在用途。 PI最近已经展示了（PRL 90，113903，2003）一种用于产生慢光的技术，该技术更容易实现，因为它需要使用室温固体。 它是基于修改的折射率分布，伴随着一种新的量子相干过程产生的光谱孔。 这种光谱空穴是由于相干布居振荡（CPO）而产生的，相干布居振荡是两个外加场之间拍频下基态布居的周期性调制。 利用这种技术，他用红宝石晶体证明了光速低至57米/秒。 相干布居振荡还可以为研究光学材料的结构特性提供极其灵敏的光谱工具。 在变翠玉中，铬离子可以位于镜像对称或反转对称的位置，这两种位置表现出不同的饱和行为。 PI已经发现（Science 301，200，2003）在某些波长处，反转位点占主导地位，变石显示出超慢传播，而在其他波长处，镜像位点占主导地位，导致超光速（但因果）传播。 问题包括通过CPO可以延迟或提前多少脉冲的基本限制，以及如何通过使用不同的材料和不同的相互作用几何形状来优化效果。 沿着这些路线的一个特别有趣的可能性涉及掺铒光纤中的光学延迟的研究，掺铒光纤是一个非常重要的系统组件。 初步的实验已经证明了这种效应的存在。 相关的问题包括如何建立基于这种效应的光学延迟线和存储设备，以及慢光和快光技术还能实现哪些其他物理和应用。 例如，预期在特定材料中的光速等于声速的条件下，将产生非常强的声光相互作用。 PI的研究小组由一个大型的不同群体的个人谁被鼓励合作，并探索他们的研究项目的智力基础。 拟议努力的主题领域是公众感兴趣的领域，事实上，公众新闻界已经报道了PI关于这一主题的早期工作。 在执行该项目期间，将举办几次关于提案主题领域的讲习班。

0355206BoydRecent research has led to the development of techniques that can allow light to propagate through a material system with a greatly reduced (or increased) group velocity. Interest in slow light results both from conceptual issues and for its potential usefulness in applications such as controllable delay lines, information storage devices, and quantum information processing. Most techniques to date for the production of slow light have been very difficult to implement, involving for instance a Bose-Einstein condensate, hot atomic vapors, or cryogenically controlled crystals.The PI has recently demonstrated (PRL 90,113903,2003)a technique for the production of slow light that is much easier to implement in that it entails the use of room-temperature solids. It is based on the modification of the refractive index profile that accompanies the spectral hole created by a novel quantum coherence process. This spectral hole is created as the result of coherent population oscillations (CPO), the periodic modulation of the ground state population at the beat frequency between two applied fields. Using this technique, he demonstrated light velocities as low as 57 m/s using a ruby crystal. Coherent population oscillations can also provide an extremely sensitive spectroscopic tool for studying the structural properties of optical materials. In the case of alexandrite, chromium ions can be located at either sites with mirror or inversion symmetry, and these two sites show different sorts of saturation behavior. The PI has found (Science 301,200,2003)that at certain wavelengths the inversion sites dominate and alexandrite shows ultra-slow propagation, whereas at other wavelengths the mirror sites dominates leading to superluminal (but causal) propagation.The proposed research program will study slow and fast light propagation in room temperature solids from several related points of view. Questions include the fundamental limitations to how much a pulse can be retarded or advanced by means of CPO and how to optimize the effect through the use of different materials and different interaction geometries. A particularly interesting possibility along these lines involves studies of optical delay in erbium doped optical fibers, an extremely important system component. Preliminary experiments have shown the existence of this effect. Related questions include how well can one build optical delay lines and storage devices based on this effect, and what other physics and applications are enabled by slow-and fast-light techniques. As an example, it is expected that there will be a very strong acoustooptic interaction under conditions such that the velocity of light in a given material becomes equal to the velocity of sound.The broader impact of the proposed activity includes the following aspects. The PI 's research group consists of a large diverse group of individuals who are encouraged to work collaboratively and to explore the intellectual underpinnings of their research projects. The subject area of the proposed effort is one that is of interest to the general public, and indeed the PI's earlier work on this topic has been covered by the popular press. Several workshops on the subject area of the proposal will be held during the course of this project.