Nonlinear Near-Field Optics of Fractal Thin Films

小行星9810183 本文研究分形薄膜中的非线性近场光学过程，即自仿射表面和二维随机金属-介质薄膜。研究的非线性光学过程包括：克尔型非线性折射和吸收，近简并四波混频，二次和更高次谐波产生。 分形薄膜的集体光激发导致“热点”，这些热点在空间中被远大于光斑尺寸的距离分开。这些空间局部化的“热点”代表分形膜的本征模。计算了分形薄膜的局域（近场）非线性谱的空间分布。通过将光子扫描隧道显微镜的尖端停在表面上的不同点并改变波长，可以在实验上获得这些光谱。获得了有关分形膜的局部配置和这些纳米尺度的随机区域的膜的共振频率的重要信息。通过分析非线性近区场的统计特性，将研究从分形膜的不同点产生的非线性场的相位和幅度相关特性，例如，通过两点相关函数。PI的理论研究有助于发展单分子和分子尺度材料的非线性光学光谱学。 ***

9810183 Shalaev This proposal is concerned with nonlinear near field optical processes in fractal thin films, namely self-affine surfaces and 2d random metal-dielectric films. Nonlinear optical processes to be investigated include: Kerr-type nonlinear refraction and absorption, nearly-degenerate four wave mixing, and second and higher harmonic generation. Collective optical excitations of fractal thin films lead to "hot" spots which are separated in space by distances much larger than the spot size. These spatially localized "hot spots" represent the eigenmodes of a fractal film. Spatial distributions of the local (near-field) nonlinear spectra on a fractal thin film will be calculated. These spectra are experimentally accessible by parking a tip of a photon scanning tunneling microscope at different points on the surface and varying the wavelength. Important information are obtained about the local configurations of a fractal film and the resonance frequencies of these nm-scale random areas of the film. Phase and amplitude correlation properties of the nonlinear fields generated from different spots of a fractal film will be studied by analyzing the statistics of the nonlinear near-zone fields, e.g., through two-point correlation functions. %%% The PI's theoretical research contributes to the development of a nonlinear optical spectroscopy of single molecules and materials of dimensions on the scale of molecules. ***