The Electrical Characterization and NIR Absorption of ITO Film under Different Sputtering Time

Indium-tin-oxide(ITO)films with different sputtering time have been prepared by dc magnetron sputtering method on PET substrate at room temperature.The film structure,thickness,electrical and optical properties are investigated through XRD,SEM,van der Pauw method and FTIR,respectively.The XRD results indicate that all the films are amorphous structure.With the increase of sputtering time,resistivity and transmittance decrease simultaneously.However the absorption gets stronger,especially in near-infrared light region.Through Drude model the plasma frequency is calculated and the calculation result is pretty consistent with films deposited at 60 and 90 min.     

含负折射率介质光子晶体的斜角禁带

研究了由正负折射率介质交替排列构成的光子晶体的传输特性,负折射率材料(NIM)是有损耗的Drude色散媒质。研究发现,这类光子晶体具有零折射率带和传统的Bragg带,此外在NIM的折射率接近于零的频域还出现了一个新型的禁带——斜角带。该斜角带的位置与晶格参数无关,其带宽较小;在电磁波垂直入射时禁带消失,但随着入射角的增大禁带逐渐展宽,且TM模的带宽大于TE模。     

线性共蒸法制备渐变折射率薄膜的光学特性分析

利用德鲁德理论和洛伦兹一洛伦茨理论，从介电常数分析人手，探讨了混合介质膜的折射率表达式，给出利用双源共蒸法镀制的渐变折射率薄膜在混合介质膜的总沉积速率恒定、两种膜料的单分子大小近似相等和沉积速率均为线性变化时的折射率表达式；从正变和负变、单周期和多周期、不同的周期数和不同的单周期厚度几个方面对渐变折射率薄膜的光学特性进行了模拟分析和讨论；对渐变折射率薄膜的实现、应用以及实验制备中有待进一步解决和处理的问题进行了讨论。     

An Improvement on the Prediction of Optical Constants and Radiative Properties by Introducing an Expression for the Damping Frequency in Drude Model

A method for predicting the optical constants and the radiative properties of metals and heat mirror films, by introducing an expression for the damping frequency in the Drude model, is described. The directional emissivity of aluminum predicted by this method agrees well with the classical experimental values given by Schmidt and Eckert. The prediction of the normal emissivity of indium–tin–oxide (ITO) heat mirror films is in agreement with our measured results. The directional emissivity of copper predicted using this method is reported. The calculated result of the spectrum normal emissivity of copper at 4 m and 20°C is also given, which supports the measured result. The values for the directional emissivity of aluminum calculated by using various methods based on the Hagen–Rubens relation are reported, and the values do not agree with the experimental results.     

Plasmonic bandgap in random media

We present a dispersion theory of the surface plasmon polaritons (SPP) in random metal-dielectric nanocomposite (MDN) consisting of bulk metal embedded with dielectric inclusions. We demonstrate that embedding of dielectric nanoparticles in metal results in the formation of the plasmonic bandgap due to strong coupling of the SPP at the metal-vacuum interface and surface plasmons localized at the surface of nanoinclusions. Our results show that MDN can replace metals in various plasmonic devices, which properties can be tuned in a wide spectral range. Being compatible with waveguides and other photonic structures, MDN offers high flexibility in the plasmonic system design.     

FeAg颗粒膜近红外光学性质的实验研究

研究了FeAg颗粒膜的光学性质.发现当Fe含量较低时,其介函数谱可以近似的用Drude模型描述,同时电子散射弛豫能量是Fe含量的线性函数,利用该性质经定标后可以确定贵金属中的杂质含量.这种方法具有简单易行、测量速度快,无损检测等优点.实验结果还表明,在近红外区,FeAg颗粒膜的介电函数谱并不能用有效介质模型很好的描述.     

Propagation characteristics of microwaves in dusty plasmas with multi-collisions

In this study, we consider three main collisions in dusty plasmas and investigate the effects of dust grains on the propagation of electromagnetic(EM) waves through uniform, unmagnetized and weakly ionized dusty plasma. The Drude model is improved to describe the dielectric property of dusty plasmas, which accounts for collisions including electron–molecule, electron–ion, and electron–dust particles. Based on the improved Drude model, the propagation characteristics of microwaves in dusty plasmas have been numerically calculated and studied.The results show that the propagation characteristics of microwaves through dusty plasmas are different from those through normal plasmas. The effects of dust density and size are mainly studied. Numerical results indicate that the momentum transfer between electrons and dust grains makes more energy loss. The dust density and dust size have a similar influence on EM wave propagation, resulting in less transmission and more absorption.     

Formulation of the finite-difference time-domain method for the analysis of axially symmetric metal nanodevices

A systematic finite-difference time-domain method, established in the cylindrical coordinate and integrated with the six-pole Lorentz–Drude model using the auxiliary differential equation method, is formulated. The model is appropriate for analyzing metal photonic devices with an axially symmetric nanostructure, such as metal nanowires, metal particles, and plasmonic lenses. As an example, an experimentally demonstrated plasmonic lens is analyzed based on the Drude model, the Lorentz–Drude model, and the Lorentz model. Depending on the different dispersion models, distinct electric field distributions for the plasmonic lens are obtained. The interesting numerical results, which are explained in this paper, show the high efficiency and accuracy of the simulation model.