A method of precise determination of the optical constants of uniaxial crystals from the compensator parameters

A method of determination of the refractive indices of uniaxial crystals from the compensator parameters is proposed. In this case, the accuracy is limited by the temperature fluctuations inside a crystal. The orientation of the optical axis with respect to the surface and the thickness and the thermal expansion coefficient of the crystal can be determined additionally. This method can be used for precise determination of the refractive indices and absorption coefficients of biaxial crystals. Experimental results of determination of the temperature coefficients of the refractive indices and of linear expansion for a plane-parallel plate cut from artificial crystalline quartz parallel to the optical axis are presented.     

Measurement of small differences in refractive indices of solutions with interferometric optical method

Based on the principles of both surface plasmon resonance (SPR) and heterodyne interferometry, an optical method for measuring small differences in refractive indices of solutions was proposed. On a specially designed probe, two light beams are incident on both reference and test solutions. The phase differences between the p- and s-polarizations of each reflected light under SPR condition are measured simultaneously with heterodyne interferometric technique. The phase values are substituted into special equations derived from Fresnel's equations. Finally, the difference between the refractive indices of these two solutions can be estimated. The feasibility of this method was demonstrated and the measurement sensitivity of refractive index can reach a value of at least 8.57×10⁻⁷. This method should bear the merits of a simple structure, easy operation, high sensitivity and rapid measurement.     

An enhanced common path interference optic measurement system for refractive indices and thickness

This study proposes a common path interference optical system for the measurement of refractive indices and thickness of uniaxial crystal material. The measurement system comprises an accurate Mach–Zehnder laser interferometer, a single-axis rotary stepping motor, and a computer. The laser interferometer is composed of a single-frequency He–Ne laser, two-beam splitters and two reflectors. The Mach–Zehnder laser interferometer measures the optical length difference by using its linear measurement accuracy. The proposed solution procedure enables both the refractive indices and the thickness of the optical waveplate to be obtained. The proposed design differs from conventional designs in that it does not use a heterodyne modulator with a lock-in technique. It is shown that the refractive indices and thickness of the tested optical elements can be measured rapidly and accurately.     

On the problem of calculating the optical film parameters from the measured transmission spectra

The procedure for calculating the dispersion of the refractive and absorption indices and thickness of an optical film, based on measurements of spectral dependence of the transmittance, is described. The film parameters are calculated using a solution of the approximation problem. The effect of the film model on the calculated values of the refractive and absorption indices is analyzed.     

用布儒斯特角法同时测定单轴晶体的折射率和光轴方向

在理论上分析了光轴任意方向的单轴晶体的折射率．根据布儒斯特角原理,当线偏振光的电场矢量平行于入射面时,通过测出对样品三个表面的布儒斯特角,就能同时确定单轴晶体的折射率和光轴方向．并利用分光计,在光轴不确定的情况下,测定了方解石的两个主折射率和光轴方向．     

Determination of Refractive Indices of a Layered Medium under Pulsed Irradiation

Problems related to determination of refractive indices of layered strongly scattering biological media by means of an optical tomography are investigated. Methods of reconstruction of refractive indices of layers, which are based on the smoothness properties of the solution to the initial-boundary problem, are proposed within the framework of the nonstationary radiative-transfer model. The influence of the probe-pulse duration on the accuracy of recovery of the sought-for characteristics of the medium is investigated numerically.     

Optical tomography problems: Investigation by the methods of the radiation transport theory

The problems of the optical diagnostics of inhomogeneous layered media are numerically studied. The question of the optical clearing of media is considered. A method for determining relative refractive indices from tomographic transmission data is proposed.     

Planar bifunctional Luneburg‐fisheye lens made of an anisotropic metasurface

Luneburg lens and Maxwell‐fisheye lens are well‐known microwave and optical devices with distinct focusing properties. Here, a planar bifunctional Luneburg‐fisheye lens made of an anisotropic metasurface is presented, which features as a Luneburg along the horizontal optical axis, while as a fisheye along the vertical optical axis. A method to control the inhomogeneous indices of refraction along the two optical axes independently is proposed by designing an anisotropic and nonuniform metasurface, which can provide the required distributions of refractive indices approximately for Luneburg and fisheye lenses viewing from the two optical axes. Experiments in the microwave frequency range demonstrate very good performance of the planar bifunctional Luneburg‐fisheye lens. The proposed method opens up an avenue to design other kinds of bifunctional devices using metasurfaces in the microwave, terahertz, and even optical ranges.     

Accurate prediction of refractive index of inorganic oxides by chemical formula

A method is proposed for estimation of mean refractive index of a complex inorganic oxide whose chemical composition is known. This method is based on using mean refractive indices of simple oxides. Applicability of the method has been tested for a representative set of ∼120 known oxide crystals. It has been shown that mean refractive index can be predicted with possible error of 0-15% depending on the chemical nature of the compound. The majority of oxides show acceptable difference <5% between theoretical and experimental refractive index values and the mean error level for a set of 124 oxide crystals is as low as ∼5%. Refractive indices of a set of simple oxides are estimated by the Lorenz-Lorentz relation. Full table of refractive indices of simple oxides for all elements of Periodic Table is proposed.     

Synthesis of broadband interference filters: II. Suppression of high reflection bands of the fourth,fifth, and sixth orders

The spectral properties of multilayer interference systems formed by multiple replication of the symmetric ternary period ABCBA are investigated. The problem of synthesis of structures with suppression of adjacent bands of high reflection of the fourth, fifth, and sixth orders among their spectral characteristics is solved. It is shown that there are only six variants of selection of the optical thicknesses of layers in a period. When the high reflection bands of the fourth, fifth, and sixth orders are suppressed, the high reflection band of the first order remains in only four cases. The values of refractive indices of layers for which the problem hasa solution are found. The refractive indices of layers in all six cases are described by different relations determining the dependence of the refractive index of one of the components on arbitrarily selected refractive indices of the other two components.     

Calculations of spontaneous emission rates of a single-impurity molecule in uniaxial host crystals

In a uniaxial host crystal the spontaneous emission rate of the dipole transition of the zero-phonon line of a single-impurity molecule depends on the angle between the transition dipole moment and the optical axis of a crystal and as well as on the ordinary and extraordinary refractive indices. The relative spontaneous emission rate (the spontaneous emission rate divided by the spontaneous emission rate in the case when the transition dipole moment is parallel to the optical axis) is determined through a simple formula by one coefficient. Here this coefficient is calculated as a function of the extraordinary refractive index for 40 values of the ordinary refractive index on the interval from 1.25 to 3.20. For comparison, the effects caused by the nearness to the plane interface between cinnabar crystal (HgS) and air, as an example, are calculated.     

基于折射率梯度门限的气动光学窗口光传输研究

基于流场界面厚度（Interfacial—Fluid—Thickness,IFT）理论,建立了高折射率梯度门限模型来研究气动光学窗口光传输畸变。首先在光学窗口折射率梯度场基础上,提出高折射率梯度门限,忽略绝对值低于该门限的折射率梯度值,重构折射率场,并对其气动光学传输效应进行仿真。结果表明,当58．37％的梯度值被忽略时,得到的重构折射率场与原折射率场仿真光程差（OPD）最大相对误差不超过1．5％,验证了气动光学窗口高折射率梯度区域是产生光传输畸变的主要原因,也证实了该门限模型对气动光学窗口光传输效应进行仿真的可行性,对气动光学失真的机理、预测及校正有一定的指导意义。     

A high-precision optical metrology system for determining the thickness of birefringent wave plates

This study develops a non-destructive measurement system for determining the thickness and refractive indices of birefringent optical wave plates. Compared to previous methods presented in the literature, the proposed metrology system provides the ability to measure the thickness of the birefringent optical plate in high-precision. The results show that for a commercially available birefringent optical wave plate with refractive indices of n_e=1.5518, n₀=1.5427 and a thickness of 452.1428 μm, the experimentally determined value for the error in the wave plate thickness measurement is just 0.046 μm. The measurement resolution of the proposed system exceeds that of the interferometer hardware itself. The proposed method provides a simple yet highly accurate means of measuring the principal optical parameters of birefringent glass wave plates.     

A spectrophotometric method for determining linear and predicting nonlinear optical properties of glass substrates

In this work, an expression for the interface reflectance in terms of both the total transmittance and the total reflectance of the glass substrate is derived. Using this expression a nondestructive procedure for deducing the complex refractive index of glass bulk material is suggested. Complex refractive indices of four glassy substrates with different thicknesses and compositions are experimentally measured across a spectral range 200–2000 nm. The errors of measurements for the suggested procedure depend on the reflectance and transmittance errors. They are calculated to be of about ±2.751 × 10^?8 for imaginary and ±0.008 for real refractive indices. Dispersive parameters of the real refractive indices and optical energy gaps for direct and indirect allowed optical transitions are deduced. Predicted nonlinear refractive indices and susceptibilities are evaluated.     

Ag+-Li+离子交换制作Er3+/Yb3+共掺磷酸盐玻璃平面光波导

制备了化学稳定的Er3+/Yb3+共掺的磷酸盐玻璃,并在其中制作了用于光放大器和激光器的平面光波导.这种磷酸盐玻璃的失重速率为4.7×10－5g·cm－2·hr－1,小于Kigre公司商业化的磷酸盐玻璃QX/Er的失重速率.采用Ag+-Li+交换技术制作了平面光波导并用m-线光谱在632.8 nm测量了平面光波导的有效折射率.根据反WKB法得到折射率形貌,计算了离子交换参数如:离子交换深度、表面折射率,折射率改变和扩散系数等.     

Optical constants of Ni nanofilms

A previously proposed ellipsometric technique for determining the refractive indices, extinction indexes, and thicknesses of metal nanofilms at optical measurements in air has been implemented for nickel films. The optical constants found for nickel, n ₂ = 2.04 ± 0.05 and k ₂ = 3.75 ± 0.05 (almost = 632.8 nm), are in agreement with the results of measurements in high vacuum. The technique proposed makes it possible to measure film thicknesses in the range of 10–30 nm with an error as small as 1 nm. However, for nickel films thinner than 10 nm, the experimental data differ significantly and deviate more strongly from the calculated values, in contrast to titanium films. Possible reasons for the discrepancy between the calculated and experimental data are discussed.     

A study of nonlinear optical properties of a negative donor quantum dot

In this paper, we studied the nonlinear optical properties of a negative donor center (D⁻) in a disk-like quantum dot (QD) with a Gaussian confining potential. Calculations are carried out by using the method of numerical diagonalization of Hamiltonian matrix within the effective-mass approximation. A detailed investigation of the linear, third-order nonlinear, total optical absorptions and refractive index changes has been carried out for the D⁻ QD and the D⁰ QD. The linear, third-order nonlinear, total optical absorptions and refractive indices have been examined for a double-electron QD with and without impurity. Our results show that the optical absorption coefficients and refractive indices in a disk-like QD are much larger than their values for quantum wells and spherical QDs and the nonlinear optical properties of QDs are strongly affected not only with the confinement barrier height, dot radius, the number of electrons but also the electron-impurity interaction.     

Second mode transition in microstructured optical fibers: determination of the critical geometrical parameter and study of the matrix refractive index and effects of cladding size

We carried out a numerical study of the second mode transition in finite-sized, microstructured optical fibers (MOFs) for several values of the matrix refractive index. We determined a unique critical geometrical parameter for the second mode cutoff that is valid for all the matrix refractive indices studied. Finite size effects and extrapolated results for infinite structures are described. Using scaling laws, we provide a generalized phase diagram for solid-core MOFs that is valid for all refractive indices, including those of the promising chalcogenide MOFs.     

Effect of cycle numbers on the structural,linear and nonlinear optical properties in Fe2O3 thin films deposited by SILAR method

Fe₂O₃ thin films were deposited by Successive Ionic Layer Adsorption and Reaction (SILAR) method onto glass substrates at different cycle numbers to investigate structural, linear and nonlinear optical properties. X-Ray Diffraction (XRD) analysis revealed that the Fe₂O₃ thin films have a non-crystalline nature. The morphological properties of the films were investigated by Field Emission-Scanning Electron Microscopy (FE-SEM) and the results show that the films’ surfaces are porous. The linear and nonlinear optical parameters were evaluated and analyzed by using transmittance and absorbance measurements. For these measurements, UV–Vis spectroscopy at room temperature was used. The refractive index values were calculated in the range of 1.45–3.23 for visible region (400–700 nm). Obtained results reveal that direct optical band gap changed between 2.62 and 2.68 eV and indirect optical band gap changed between 1.67 and 1.77 eV. Additionally, optical electronegativity, optical dielectric constants, surface and volume energy loss functions, nonlinear refractive index, linear optical susceptibility, third-order nonlinear optical susceptibility, optical and electrical conductivity, and loss tangent values were calculated and discussed in detail. It was found that each parameter studied is dependent on the cycle numbers. Also, it can be stated that Fe₂O₃ thin films are promising candidate for solar cells and optoelectronic device technology.     

基于透射光谱确定溶胶凝胶ZrO2薄膜的光学常数

基于溶胶凝胶ZrO₂薄膜的紫外/可见/近红外透射实验光谱,采用Swanepoel方法结合Wemple-DiDomenico色散模型,方便地导出了ZrO₂薄膜在200—1200nm波长范围内的光学常数,包括折射率、色散常数、膜层厚度、吸收系数及能量带隙.研究发现,溶胶凝胶ZrO₂薄膜具有高折射率(1.63—1.93,测试波长为632.8nm)、低吸收和直接能量带隙(4.97—5.63eV) 等光学特性,而且其光学常数对薄膜制备过程中的重要工艺 关键词： 光学常数 Swanepoel方法 2薄膜')" href="#">ZrO₂薄膜 热处理