New Perspectives on Wave Propagation in Random Media

*技术摘要*测量输出面处的微波场图样的频谱以及沿无序样品长度的一条线上的测量将提供关于波的传输的全面图景。相关测量将使用激光和空间光调制器和CCD相机进行。对这些测量结果的分析将得到时域有限差分数值模拟的补充。这项研究将从四个不同的角度研究波的传输及其相互关系：(1)模和(2)传输本征道的空间结构，以及(3)局部扩散系数和(4)扩散波和局域波的场散斑图样随位置的变化。在单个样本中确定的波统计将指导应用程序在随机系统中进行聚焦、成像和增强传输。利用微波辐射和光传播的基础和应用方面的联合实验、理论和数值研究将为参与这项研究的本科生、研究生、高中生和博士后提供理想的学习经验。这项工作将加强CUNY的光子学倡议，并在纽约市地区促进光子学技术。*非技术摘要*波在随机介质中传播的方式会影响我们的通信和成像能力以及制造电子和光电子设备的能力。由于探测散射样品内部和测量整个散射场的双重困难，多次散射系统中的波的研究更具挑战性。在这个项目中，我们将测量微波辐射源和光源在无序样品输出的不同位置产生的波型，以及无序样品内部的微波辐射。这套完整的测量将使我们能够确定每个随机样品中波的自然振荡模式和特定传输通道，以及波的位置相关流量和强度，以及整个样品中强度波动的性质。这项工作将在随机系统中实现最佳聚焦，并将产生几乎完全的传输，即使在通常不透明的系统中也是如此。使用微波和激光测量来挑战基本和应用问题将促进研究生、本科生、高中生和参与研究的博士后的教育和职业生涯。这项工作的成功将加强为加强纽约市大都市区的技术基础而建立的城市大学光子中心。

****Technical Abstract****Measurements of the spectrum of the microwave field pattern at the output surface and on a line along the length of disordered samples generated by a source moved to points on a grid over the sample's input surface will provide a comprehensive picture of waves transport. Related measurements will be carried out using laser light and a spatial light modulator and CCD camera. The analyses of these measurements will be supplemented with finite difference time domain numerical simulations. This research will advance four distinct perspectives on wave transport and the relationships between them: the spatial structure of (1) modes and (2) transmission eigenchannels, as well as the variation with position of (3) the local diffusion coefficient, and (4) the field speckle pattern for both diffusive and localized waves. Wave statistics determined in single samples will guide applications to focusing, imaging, and enhanced transmission in random systems. The joint experimental, theoretical and numerical study of fundamental and applied aspects of propagation using microwave radiation and light will provide and ideal learning experience for the undergraduate, graduate, and high school students and the postdoctoral fellow involved in this research. The work will strengthen the photonics initiative at CUNY and foster photonic technological in the New York City area. ****Non-Technical Abstract****The manner in which waves propagate in random media affects our ability to communicate and image and to create electronic and photonics devices. The study of waves in multiply-scattering systems is all the more challenging because of the twin difficulties of probing the interior of scattering samples and measuring the full scattered field. In this project, we will measure the wave pattern generated by sources of microwave radiation and light at various positions on the output of disordered samples as well as microwave radiation in the interior of such samples. This full set of measurements will allow us to determine the natural modes of oscillation as well as the specific transmission channels for waves in each random sample as well as the position dependent flux and intensity of the wave and the nature of fluctuations of intensity throughout the sample. The work will enable optimal focusing through and within random systems and will yield nearly complete transmission even in ordinarily opaque systems. The use of both microwave and laser measurements for challenging fundamental and applied problems will advance the education and careers of graduate students, undergraduates, high school students and a postdoctoral fellow involved in the research. The success of this work will strengthen the CUNY Photonic Center established to enhance the technological base of the New York City metropolitan area.