Collaborative Research: Mesoscopic Transport and Localization in Active Random Media

****非技术摘要****光散射解释了我们日常生活中的许多现象，例如，天空是蓝色的，牛奶是白色的。如果散射很强，光的粒子——光子——就会“迷失在丛林中”，光就会停滞不前。这种现象被称为局部化，最初是在凝聚态物理中引入的。与电子不同，光子的数量可以成倍增加。当一个光子最终从“丛林”中出现时，很难分辨它是原始光子随机游走过程中产生的输入光子还是另一个光子。该项目的目标是通过进行数值模拟和实验跟踪“丛林”中的光子来了解光定位和放大之间的相互作用。从提出的工作中获得的物理见解可能会导致新的光学技术的发展，用于光散射强的生物组织的非侵入性实时表征。此外，该项目的结果将有助于理解随机激光器-一种由随机介质制成的非常规激光器。这个跨学科性质的合作研究项目将影响凝聚态物理和光学。参与该项目的研究生和本科生将接受广泛的培训。拟议的教育活动包括课程发展和教育外展，这将丰富参与院校的研究和教育环境。****技术摘要****在电子系统中没有对应的光子相干放大，为介观输运和安德森局域化的基础研究增加了一个新的维度。本项目的主要目标是了解相干放大对随机介质中介观波输运的影响。该合作研究项目结合了二维随机系统中光输运和局域化的实验和数值研究。近场扫描光学显微镜将用于研究局部场和强度的统计特性，包括空间和光谱相关性，场和强度分布和矩。这些研究将为定位和扩增之间复杂的相互作用提供物理见解，从而制定主动随机系统中安德森定位的标准。实验小组和理论小组之间的密切合作对拟议研究计划的成功至关重要。参与这个跨学科项目的研究生和本科生将在凝聚态物理和光学方面接受广泛的培训。拟议的教育活动包括课程发展和教育外展，这将丰富参与院校的研究和教育环境。

****NON-TECHNICAL ABSTRACT****Light scattering accounts for many phenomena in our daily life, e.g., the sky is blue, milk is white. If the scattering is strong, light can be brought to a standstill as the particles of light - photons - get "lost in a jungle". This phenomenon, called localization, was first introduced in condensed matter physics for electrons. Unlike electrons, the number of photons can be multiplied. When a photon eventually emerges from the "jungle", it is hard to tell whether it is the input one or another one created during the random walk of the original photon. The goal of the project is to understand the interplay between light localization and amplification by performing numerical simulations and experimentally tracking the photons in the "jungle". The physical insight obtained from the proposed work may lead to the development of new optical techniques for non-invasive real-time characterization of biological tissues in which light scattering is strong. Also, the outcome of the project will be instrumental in understanding the random laser - an unconventional laser made of random medium. The interdisciplinary nature of this collaborative research program will impact both condensed matter physics and optics. The graduate and undergraduate students involved in this program will receive extensive training. The proposed education activities include the curriculum development and educational outreach, which will enrich the research and education environments at the participating institutions.**** TECHNICAL ABSTRACT****Without a counter-part in electronic systems, coherent amplification of photons adds a new dimension to the fundamental study of mesoscopic transport and Anderson localization. The main goal of this project is to understand the effects of coherent amplification on mesoscopic wave transport in random dielectric media. The collaborative research program combines experimental and numerical studies on light transport and localization in two-dimensional random systems with gain or absorption. Near-field scanning optical microscopy will be employed to investigate the statistical properties of local fields and intensities, including the spatial and spectral correlations, the field and intensity distributions and moments. These studies will provide physical insight into the intricate interplay between localization and amplification, enroute to formulating the criterion of Anderson localization in active random systems. The close collaboration between an experimental and theoretical group is crucial to the success of the proposed research program. The graduate students and undergraduate students involved in this interdisciplinary program will receive extensive training in both condensed matter physics and optics. The proposed education activities include the curriculum development and educational outreach, which will enrich the research and education environments at the participating institutions.