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arXiv 1303.3244physics.opticscond-mat.dis-nn
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无序波导中光的位置相关扩散

Position-dependent diffusion of light in disordered waveguides

Alexey G. Yamilov, Raktim Sarma, Brandon Redding, Ben Payne, Heeso Noh, Hui Cao

摘要:

扩散已被广泛用于描述粒子或波的随机行走,它只需要一个参数-扩散常数。然而,对于波,扩散是一种近似,忽略了干涉的可能性。安德森局域化通过无限系统中扩散系数的消失而表现出来,它起源于在回路轨迹中行进的波的相长干涉--回路轨迹是返回同一点的时间反演路径对。在有限大小的开放系统中,通过这些路径的返回概率降低,特别是在波可能逃逸的边界附近。基于这一论点,自洽的局域化理论和超对称场论预测,扩散系数在系统内部空间变化。对这种效应的直接实验观察是一个挑战,因为它需要监测系统内部的波传输。在这里,我们制作了二维光子随机介质和探针的位置依赖的扩散从第三维的样品内。通过改变系统的几何形状或耗散,这也限制了循环轨迹的大小,我们能够控制扩散系数的重整化。这项工作表明,通过本地化和耗散的相互作用操纵扩散的可能性。

英文摘要:

Diffusion has been widely used to describe a random walk of particles or waves, and it requires only one parameter -- the diffusion constant. For waves, however, diffusion is an approximation that disregards the possibility of interference. Anderson localization, which manifests itself through a vanishing diffusion coefficient in an infinite system, originates from constructive interference of waves traveling in loop trajectories -- pairs of time-reversed paths returning to the same point. In an open system of finite size, the return probability through such paths is reduced, particularly near the boundary where waves may escape. Based on this argument, the self-consistent theory of localization and the supersymmetric field theory predict that the diffusion coefficient varies spatially inside the system. A direct experimental observation of this effect is a challenge because it requires monitoring wave transport inside the system. Here, we fabricate two-dimensional photonic random media and probe position-dependent diffusion inside the sample from the third dimension. By varying the geometry of the system or the dissipation which also limits the size of loop trajectories, we are able to control the renormalization of the diffusion coefficient. This work shows the possibility of manipulating diffusion via the interplay of localization and dissipation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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