椭圆偏振法测定在线Low-E玻璃的可见-近红外光学常数与膜厚

从在线Low-E玻璃光学机理出发,用椭圆偏振光谱仪对在线Low-E玻璃功能层和过渡层的可见-近红外波段的光学常数进行研究.测量了样品在三个不同入射角的椭偏参数,分别用Lorentz双振子模型和Cauchy模型来描述Low-E玻璃功能层和过渡层的光学色散特性.通过拟合椭偏参数获得在线Low-E玻璃的光学常数及每层膜厚度,并用扫描电镜对样品的膜厚进行表征.结果表明,Lorentz双振子模型和Cauchy模型能很好地解释在线Low-E玻璃的光学特性;同时,椭圆偏振法也为多层膜系统提供了一种测定光学常数和膜厚的可靠方法.     

酞菁铜LB薄膜复合光波导的高速双稳特性

对以有机材料酞菁铜的LB薄膜作覆盖层的K~+离子交换玻璃光波导,进行了高速光学双稳特性研究.利用比较波导的输入和输出光脉冲形状法,在532nm光波长得到开关时间为24ps的高速光学双稳特性.     

基于磁光力系统的相干光学传输特性研究

提出了一个包含磁振子-声子-光子三者相互作用的磁光力系统,该系统由一个磁振子(钇铁石榴石小球)和一个光学谐振腔构成.在该系统中,利用大量自旋的亚铁磁体的集体运动来表征磁振子,并且磁振子和光子通过磁偶极子相互作用耦合,磁振子和声子通过磁致伸缩相互作用耦合.利用严格的量子光学理论与输入-输出关系理论,研究了该系统中的相干光学传输特性.通过调控该系统中的参数,实现了对输出场的有效调控,为宏观量子现象的研究提供了一个有前景的平台.     

金属介电常数的色散模型对光学Tamm态的影响

比较银介电常数三种色散模型对光学Tamm态的影响,根据三种色散模型的复折射率随波长的变化研究银-光子晶体-银结构TE波和TM波的光学Tamm 态随入射角、银层厚度及周期数的变化.得出：三种色散模型下银-光子晶体-银结构中都会出现两个光学Tamm 态（OTS1和OTS2）.三种色散模型下的光学Tamm 态的波长随入射角、银层厚度及周期数的变化规律一致.但是光学Tamm 态的透射峰值随入射角、银层厚度及周期数的变化规律不一致.Drude-Lorentz模型和Lorentz模型能够描述银的特征,而Drude模型不能.     

反射率和吸收系数对激光材料作用的影响

光学特性参数在模拟精度上起着关键性作用,决定了激光照射过程中薄膜上能量沉积的量.本文采用三种不同的描述激光和材料相互作用过程中金薄膜光学参数的模型对室温状态下金膜表面的反射率和吸收系数进行了模拟研究,并将结果和实验数据做了对比,结果发现在室温下扩展Drude模型的计算结果能和实验数据吻合良好.论文进而采用此模型模拟了激光照射金薄膜的传热过程,并分析讨论了将光学参数按定值处理和按变量处理时的不同.     

多光子光学双稳性的研究

本文给出了描述多光子光学双稳性和多光子激光的统一量子力学模型,得到了多光子光学双稳性和多光子激光的态方程,给出了计算多光子光学双稳住阈值的方法.对势函数进行分析之后,得到了静态稳定性判据和开关特性的物理解释,划分了多光子光学双稳特性曲线上的稳定区域和亚稳定区域,指出多光子光学双稳态实际上是多光于光学稳-亚稳双态.本文还讨论了多光子光学双稳态和多光子激光器中的相变问题.     

Bi_(12)GeO_(20)的旋光性和法拉第效应

在4300～8000(?)波长范围研究了Bi_(12)GeO_(20)的旋光性和法拉第效应.分析表明,锗酸铋的旋光频散特性可以用Drude的分子旋光模型来描述.它的较强的法拉第效应使它有可能用于光学非互易器件或偏振旋转器中.     

1.3μm InGaAsP/InP双异质结发光管的特性研究

用液相外延技术生长的三层和四层InGaAsP/InP双异质结材料,制成了1.3μm InGaAsP/InP双异质结发光管。光功率输出(100mA)>1.0mW,最高2mW,尾纤输出功率(N.A.0.23,芯径60μ)>50μW。文中描述了器件的特性参数,还讨论了光功率的饱和特性和退化特性。     

光学玻璃的发展及其应用

随着光子学技术的发展，利用玻璃和光的相互作用改变光的极化态、频率、相干性和单色性，以及产生光子和探测光子的新型光功能玻璃成为光学玻璃发展的主要方向。本文针对光学玻璃及其在光学和信息技术等相关应用领域的重要性和发展作了介绍，重点阐述了非线性光学玻璃、梯度折射率光学玻璃、激光玻璃以及其他光功能玻璃的主要特性和发展状况，并对我国的光学玻璃工业发展作了回顾。     

光栅光阀器件的结构改进与制作工艺研究

根据光栅光阀的工作原理,在结构上对传统的光栅光阀器件进行了改进,分析了改进后光栅光阀器件的光学特性、结构特性,以及制作工艺流程.改进后的光栅光阀结构中硅基底上设有二氧化硅隔离层,隔离层上沉积无定形硅作为牺牲层,可动梁的材料是氮化硅,固定梁为蒸镀的金属铝层.通过离子刻蚀的方法刻蚀图形,用化学腐蚀方法掏空牺牲层得到所需桥梁状结构.研究表明改进后的器件黑区范围小,驱动电压较低,光学效率较高,具有潜在的应用前景.     

Correlation effects obtained from optical spectra of Fe-pnictides using an extended Drude-Lorentz model analysis

We introduce an analysis model, an extended Drude–Lorentz model, and apply it to Fe-pnictide systems to extract their electron–boson spectral density functions (or correlation spectra). The extended Drude–Lorentz model consists of an extended Drude mode for describing correlated charge carriers and Lorentz modes for interband transitions. The extended Drude mode can be obtained by a reverse process starting from the electron–boson spectral density function and extending to the optical self-energy and, eventually, to the optical conductivity. Using the extended Drude–Lorentz model, we obtained the electron–boson spectral density functions of K-doped BaFe₂As₂ (Ba-122) at four different doping levels. We discuss the doping-dependent properties of the electron–boson spectral density function of K-doped Ba-122. We also can include pseudogap effects in the model using this approach. Therefore, this approach is very helpful for understanding and analyzing measured optical spectra of strongly correlated electron systems, including high-temperature superconductors (cuprates and Fe-pnictides).     

Drude Weight,Optical Conductivity of Two-Dimensional Hubbard Model at Half Filling

We study the Drude weight D and optical conductivity of the two-dimensional (2D) Hubbard model at half filling with staggered magnetic flux (SMF). When SMF being introduced, the hopping integrals are modulated by the magnetic flux. The optical sum rule, which is related to the mean kinetic energy of band electrons, is evaluated for this 2D Hubbard Hamiltonian. Our present result gives the dependence of the kinetic energy, D and the optical conductivity on SMF and U. At half filling D vanishes exponentially with system size. We also find in the frequency dependence of the optical conductivity, there is δ-function peak at ω≈2|m|U and the incoherent excitations begin to present themselves extended to a higher energy region.     

ZnSe体单晶THz波段时域光谱测量及分析

利用透射型THz时域光谱技术,对ZnSe(110)体单晶在THz波段的色散和吸收性质进行了测量和分析。根据Drude理论获得了ZnSe体单晶的静电介电常数及高频介电常数,并观察到ZnSe体单晶在THz波段的多声子吸收效应。     

红外光学薄膜材料光学常量计算和在宽带增透膜中的应用

使用经典洛伦兹谐振子模型对热蒸发制备的锗、硫化锌以及低吸收稀土氟化物薄膜的红外透射光谱进行拟合,得出这些材料在中长波红外区的光学常量.使用这三种材料设计并制备了锗窗口7.7~15μm宽带增透膜系,通过优化设计并且使用长波红外区吸收小的低折射率材料,在长波区(13~15μm)的透过率测量值有明显提高,15μm处的透过率为89.9％.     

Collisional, Nonuniform Plasma Sphere Scattering Calculation by FDTD Employing a Drude Model

In a collisional plasma, the collision frequency between electrons and neutrals may be equal to or greater than incident electromagnetic wave frequency. The complex permittivity can not represent the dielectric property of the plasma perfectly used in the finite difference in time domain (FDTD). Drude model is adopted to characterize a collisional plasma. Using a commercial FDTD package, XFDTD 6.0, the electromagnetic scattering of plasma sphere is calculated. By comparison with Mie method, Drude mode is proven to be suitable. Radar cross-section (RCS) of nonuniform plasma spheres and conductor spheres coated by plasma layer are calculated.     

Dynamic conductivity modified by impurity resonant states in doping three-dimensional Dirac semimetals

The impurity effect is studied in three-dimensional Dirac semimetals in the framework of a T-matrix method to consider the multiple scattering events of Dirac electrons off impurities. It has been found that a strong impurity potential can significantly restructure the energy dispersion and the density of states of Dirac electrons. An impurity-induced resonant state emerges and significantly modifies the pristine optical response. It is shown that the impurity state disturbs the common longitudinal optical conductivity by creating either an optical conductivity peak or double absorption jumps, depending on the relative position of the impurity band and the Fermi level. More importantly, these conductivity features appear in the forbidden region between the Drude and interband transition, completely or partially filling the Pauli block region of optical response. The underlying physics is that the appearance of resonance states as well as the broadening of the bands leads to a more complicated selection rule for the optical transitions, making it possible to excite new electron-hole pairs in the forbidden region. These features in optical conductivity provide valuable information to understand the impurity behaviors in 3D Dirac materials.     

Investigation of the linear and nonlinear properties of a Drude model photonic crystal

The optical transmission properties of a one-dimensional Drude model photonic crystal are investigated. The linear wave propagation is studied by the transfer matrix method. Using a delta-function approximation a nonlinear 2-d map is obtained and used to explore the global transmission properties of nonlinear wave propagation in this system. Inclusion of a frequency-dependent refractive index represented by the Drude model results in a considerable modification of the characteristics of the linear and nonlinear wave propagation of the one-dimensional photonic crystal.     

A first-principles molecular dynamics approach for predicting optical phonon lifetimes and far-infrared reflectance of polar materials

The Lorentz oscillator model is well-known for its effectiveness to describe the far-infrared optical properties of polar materials. The oscillator strength and damping factor in this model are usually obtained by fitting to experimental data. In this work, a method based on first-principles simulations is developed to parameterize the Lorentz oscillator model without any fitting parameters. The high frequency dielectric constant is obtained from density functional perturbation theory, while the optical phonon frequencies and damping factors are calculated using an analysis of ab initio molecular dynamics trajectories. This method is then used to predict the far-infrared properties of GaAs, and the results are in good agreement with experimental data.     

基于Kramers-Kronig关系建立金属太赫兹色散模型

提出了一种基于测量反射率谱、使用Kramers-Kronig(KK)关系建立金属太赫兹色散模型的方法.结合合金铝和合金铜4—40 THz的测量反射率谱,通过反射系数振幅和相位的KK关系,采用高频端指数外推,低频端常数外推的方法,反演金属复折射率.以KK反演的复折射率作为实验值,以拟合复折射率和实验值误差最小为准则,使用遗传优化算法,拟合了合金铝和合金铜的Drude色散参数(等离子频率和碰撞频率).基于优化的Drude模型计算了0.1—40 THz材料的复折射率,与椭偏仪的实测结果符合,验证了模型的准确性.该方法理论与实验相互验证,以测量的复折射率作为实验定标,将远红外频段的色散信息拓展到太赫兹频域,确定了太赫兹频段金属的微观物理参数,提供了太赫兹频段色散和散射机理的研究依据.     

Controlling electric field distribution by graded spherical core-shell metamaterials

This paper investigates analytically the electric field distribution of graded spherical core-shell metamaterials, whose permittivity is given by the graded Drude model. Under the illumination of a uniform incident optical field, the obtained results show that the electrical field distribution in the shell region is controllable and the electric field peak’s position inside the spherical shell can be confined in a desired position by varying the frequency of the optical field as well as the parameters of the graded dielectric profiles. It has also offered an intuitive explanation for controlling the local electric field by graded metamaterials.