银-绝缘体纳米复合材料的有效介电常数

Gain assisted nanocomposite multilayers with near zero permittivity modulus at visible frequencies

We have fabricated a layered nano-composite by alternating metal and gain medium layers, the gain dielectric consisting of a polymer incorporating optically pumped dye molecules. Exploiting an improved version of the effective medium theory, we have chosen the layers thicknesses for achieving a very small value of the real part of the permittivity epsilon_\| (parallel to the layers plane) at a prescribed visible wavelength. From standard reflection-transmission experiments on the optically pumped sample we show that, at a visible wavelength, both the real and the imaginary parts of the permitt…

Optimizing the Drude-Lorentz model for material permittivity - method, program, and examples for gold, silver, and copper

Approximating the frequency dispersion of the permittivity of materials with simple analytical functions is of fundamental importance for understanding and modeling the optical response of materials and resulting structures. In the generalized Drude-Lorentz model, the permittivity is described in the complex frequency plane by a number of simple poles having complex weights, which is a physically relevant and mathematically simple approach: By construction, it respects causality represents physical resonances of the material, and can be implemented easily in numerical simulations. We report he…

Spectral domain inverse design for accelerating nanocomposite metamaterials discovery

Inverse design techniques in the context of nanophotonics have helped in discovery of compact and counter-intuitive structures/shapes. We introduce the concept of spectral domain inverse design to search through the optical trade-space (dispersive permittivity) of nanocomposite metamaterials. We develop a hybrid optimization technique that combines genetic algorithms and gradient descent methods. We utilize this technique to inverse design an ultra-thin thermophotovoltaic emitter coating material. Our work can lead to an efficient approach to search for new multi-functional optical/thermal met…

各向异性、立方非线性、均匀化纳米复合材料的非零体积退极化区

Depolarization regions of nonzero volume for anisotropic, cubically nonlinear, homogenized nanocomposites

提出了一种基于强介电常数涨落理论（SPFT）的均质复合材料（HCM）本构参数估计方法。与均匀化的常规方法不同，本文中假设构成组分材料相的颗粒是小的，但不是消失的小。通过一个有代表性的数值例子说明了颗粒尺寸对HCM本构参数估计的影响。据观察，考虑到非零的颗粒尺寸，预测衰减和非线性增强有所减少。在这些方面，颗粒尺寸的影响是类似的，在bilocally-approximately SPFT的相关长度。

基于环氧-银纳米复合材料的纸基比色传感器用于检测水中氯离子

Paper-based colorimetric sensor for detection of chloride anions in water using an epoxy-silver nanocomposite

本文提出一种基于环氧-银纳米复合材料的纸基比色传感器，通过银纳米颗粒被氯离子氧化刻蚀并形成链状聚集体产生颜色变化，实现对水中Cl⁻的高特异性、宽范围、低检测限快速检测。

Complex-k modes of plasmonic chain waveguides

Nanoparticle chain waveguide based on negative-epsilon material is investigated through a generic 3D finite-element Bloch-mode solver which derives complex propagation constant ($k$). Our study starts from waveguides made of non-dispersive material, which not only singles out "waveguide dispersion" but also motivates search of new materials to achieve guidance at unconventional wavelengths. Performances of gold or silver chain waveguides are then evaluated; a concise comparison of these two types of chain waveguides has been previously missing. Beyond these singly-plasmonic chain waveguides, w…