Nonlinear optics of random metal-dielectric films
Nonlinear optics of random metal-dielectric films
复制标题
DOI：
10.1109/nlo.1998.710161
复制
发表时间：
1998-05
期刊：
影响因子：
--
通讯作者：
V. M. Shalaev;A. Sarychev
中科院分区：
文献类型：
--
作者：
V. M. Shalaev;A. Sarychev
随机金属-电介质薄膜（也称为非连续金属薄膜）的光学性质引起了极大的兴趣，在很大程度上是因为它们在各种应用中的高潜力。二维（2d）非连续金属膜通常通过将金属热蒸发或溅射到绝缘（电介质）衬底上来制备。在生长过程中，首先在衬底上形成小的金属颗粒。随着薄膜的生长，金属浓度增加，并发生聚结，从而在衬底上形成不规则形状的簇，最终导致2d分形结构。在逾渗阈值时，分形结构的尺寸发散，并且在样品的端部之间出现连续的金属导电路径。在较高的表面覆盖率下，膜主要是金属的，具有不规则分形形状的空隙。随着进一步覆盖的增加，膜变得均匀。我们使用一种基于真实的空间重整化群（RSRG）方法的非常有效的数值方法，计算了连续薄膜在基频和产生（非线性光学过程）频率下的场分布。我们的RSRG计算表明局部电场强度的大波动。
The optical properties of random metal-dielectric thin films (referred also to as semicontinuous metal films) are of great interest, in large part because of their high potential for various applications. Two-dimensional (2d) semicontinuous metal films are usually produced by thermal evaporation or sputtering of metal onto an insulating (dielectric) substrate. In the growing process small metallic grains are formed on the substrate first. As the film grows, the metal concentration increases and coalescences occur, so that irregularly shaped clusters are formed on the substrate eventually resulting in 2d fractal structures. At the percolation threshold, the sizes of the fractal structures diverge and a continuous conducting path of metal appears between the ends of the sample. At higher surface coverage, the film is mostly metallic, with voids of irregular fractal shapes. As further coverage increases, the film becomes uniform. We calculated the field distributions on a semicontinuous film at the fundamental and generated (in nonlinear optical processes) frequencies using a very effective numerical method based on the real space renormalization group (RSRG) approach. Our RSRG calculations demonstrate the large fluctuations for the intensity of the local electric fields.