Nanolocalization of time-reversed coherent optical fields in random scattering media

位于纳米级随机散射环境中的纳米级光发射器的远场发射图案包含关于局部发射的信息。由于电磁波传播时间反转的互易性，传出波产生传播回到发射器并定位在子衍射限制长度尺度上的激励。在微波领域，这种纳米定位最近通过选择性地寻址仅以λ/30（G. Lerosey等人，Science 315（2007）1120）。此外，在第二个资助期内，我们建议实验性地展示基于电磁波谱可见光范围内的时间反转场的辐射纳米定位。在第一个资助期内进行的理论和实验研究表明，纳米纹理层状材料，因为它们被用于薄膜太阳能电池，以提高吸收效率，非常适合研究光在一个维度上的定位。散射辐射的光谱相位和振幅的特征在于光谱干涉测量和矢量场合成器允许反向传播的时间反转场。双光子荧光被用来证明，时间反转的字段确实表现出时空聚焦的分层结构。与自适应优化和未成形脉冲的比较允许通过时间反转估计纳米定位的效率。使用相同的技术，纳米粒子聚集体作为随机光学纳米天线将被用来证明在三维定位。此外，我们将研究如何nanolocalization的散射介质中的耗散的影响，偏振自由度和纳米结构的属性（响应中的共振，混响室）。除了时间反转场的奈米定域化，我们也将研究随机散射介质中光传播与定域化的适应性最佳化。模型计算表明，在时间反演领域的nanolocalization相比，一个显着改善的选择性的局部激发预期自适应优化领域。我们的目标是证明时空激励控制适当设计和染料功能化的随机纳米天线。除了时间反转场的奈米定域化，我们也将研究随机散射介质中光传播与定域化的适应性最佳化。模型计算表明，在时间反演领域的nanolocalization相比，一个显着改善的选择性的局部激发预期自适应优化领域。我们的目标是证明时空激励控制适当设计和染料功能化的随机纳米天线。

The far field emission pattern of a nanoscale light emitter positioned in a nanoscale random scattering environment contains information about the localized emission. Because of the reciprocity of electromagnetic wave propagation time-reversing the outgoing wave creates an excitation that propagates back to the emitter and localizes on a sub-diffraction limited length scale. In the microwave regime this nanolocalization was recently demonstrated by selectively addressing microwave antennas separated only by λ/30 (G. Lerosey, et al., Science 315 (2007) 1120). Also for the second funding period we propose to experimentally demonstrate nanolocalization of radiation based on time-reversed fields in the visible range of the electromagnetic spectrum. The theoretical and experimental investigations performed in the first funding period have shown that nanotextured layered materials, as they are used in thin film solar cells to increase the absorption efficiency, are well suited to investigate light localization in one dimension. Spectral phase and amplitude of the scattered radiation is characterized by spectral interference measurements and a vector field synthesizer allows back-propagating the time reversed field. Two-photon fluorescence is used to demonstrate that the time reversed fields indeed exhibit spatiotemporal focusing in the layered structure. Comparison with adaptively optimized and unshaped pulses allows estimating the efficiency of nanolocalization via time reversal. Using the same technique, nanoparticle aggregates acting as random optical nanoantennas will be used to demonstrate localization in three dimensions. In addition we will investigate how the nanolocalization is influenced by dissipation in the scattering medium, the polarization degree of freedom and the properties of the nanostructure (resonances in the response, reverberation chamber). Besides the topic of nanolocalization of time reversed fields we will also study the adaptive optimization of light propagation and localization in random scattering media. The model calculations show that in comparison to nanolocalization of time-reversed fields a significantly improved selectivity of the local excitation is expected for adaptively optimized fields. The goal is to demonstrate spatiotemporal excitation control in suitably designed and dye-functionalized random nanoantennas. Besides the topic of nanolocalization of time reversed fields we will also study the adaptive optimization of light propagation and localization in random scattering media. The model calculations show that in comparison to nanolocalization of time-reversed fields a significantly improved selectivity of the local excitation is expected for adaptively optimized fields. The goal is to demonstrate spatiotemporal excitation control in suitably designed and dye-functionalized random nanoantennas.