共查询到20条相似文献,搜索用时 15 毫秒
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In this paper, we present simulation results of an electrooptical variable optical attenuator (VOA) integrated in silicon-on-insulator waveguide. The device is functionally based on free carriers absorption to achieve attenuation. Beam propagation method (BPM) and two-dimensional semiconductor device simulation tool PISCES-II were used to analyze the dc and transient characteristics of the device. The device has a response time (including rise time and fall time) less than 200 ns, much faster than the thermooptic and micro-electromechanical systems (MEMSs) based VOAs. 相似文献
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V. V. Voitylov P. I. Ivashchenko A. A. Trusov I. V. Altukhov 《Optics and Spectroscopy》2009,107(5):717-720
Results of an electrooptical study of a water solution of carbon nanotubes obtained using the catalytic method are presented.
It is shown that nanotubes, which anisotropically absorb light, are oriented in an electric field and create a pronounced
linear electric dichroism due to light absorption, rather than light scattering (as in the case of colloids with particles
with sizes close to that of nanotubes). An analysis of the relaxation dependences of the electric dichroism shows that nanotubes
deform, which are oriented in the electric field; in this case, the deformation sublinearly depends on the field amplitude
and reaches a limiting value. The relaxation dependence of the field-induced dichroism agrees with the autocorrelation function
of depolarized light scattered perpendicular to the incident light flux. 相似文献
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The passage of a light ray through an anisotropic medium with a refractivity gradient is analyzed here, on the basis of the Fermi principle, and the results are applied to an electrooptical deflector crystal. Two modes of deflector operation are considered, corresponding to different polarizations of a light ray relative to the plane in which it deflects. It is shown that, when the refractive index varies only little (n/n 1), the linear theory describes very accurately both modes.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 22–25, September, 1974. 相似文献
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Stabilization of spiral wave and turbulence in the excitable media using parameter perturbation scheme 下载免费PDF全文
This paper proposes a scheme of parameter perturbation to suppress the stable rotating spiral wave, meandering spiral wave and turbulence in the excitable media, which is described by the modified Fitzhug-Nagumo (MFHN) model. The controllable parameter in the MFHN model is perturbed with a weak pulse and the pulse period is decided by the rotating period of the spiral wave approximatively. It is confirmed that the spiral wave and spiral turbulence can be suppressed greatly. Drift and instability of spiral wave can be observed in the numerical simulation tests before the whole media become homogeneous finally. 相似文献
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A. A. Berezhnoĭ 《Optics and Spectroscopy》2002,92(3):459-464
Results of studying the conditions for optimum electrooptical (EO) interaction in lithium niobate crystals are presented. Analytical formulas are obtained for calculating refractive indices of natural waves and their polarizations for basis X-, Y-, and Z-cuts of crystals for arbitrary orientations of the wave vector of an optical wave. Conditions are found for the appearance of intermode EO interaction causing the orientation of polarization plane of natural waves to become a function of the external electric field. 相似文献
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We present all order results for the heavy top corrections to the ρ parameter in the complex mass scheme. We derive translation formulas between the complex mass and the on-shell scheme and show that they are ultimately equivalent. We show that a naive treatment with a fixed width for the top quark cannot give even approximately correct results. 相似文献
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The strain polarizability parameter λ for alkali halides under the effect of hydrostatic pressure has been evaluated. The correlations of λ with fractional ionic character, effective ionic charge and the overlap repulsive energy have been pointed out. 相似文献
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Electrooptical Kerr effect has been studied in binary solutions of a dipolar liquid (-picoline, β-picoline) in a non-dipolar solvent (benzene, p-xylene) and 1,4-dioxane in the full range of concentrations of the dipolar component (0 ≤ f2 ≤ 1). The experimental Kerr constant Ks of the solutions, refraction index ns, density ρs and the dielectric constant εs have been measured and used for the calculation of the molar Kerr constants KSM within the Onsager local field model. Analysis of changes in the molar Kerr constants as a function of the solute concentration by fits of theoretical functions to the experimental ones has permitted a determination of the parameters characterizing intermolecular interactions in binary solutions. 相似文献
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The linear electrooptical effect in uniaxial crystals is considered with the aid of direct tensor methods. Covariant expressions for finding biradials and ray refractive indices are developed. A general expression is derived relating the nonlinear optical polarizability parameters and the electrooptical properties of a crystal. The results are applied to cuts of uniaxial ammonium dihydrogen phosphate (ADP), potassium dihydrogen phosphate (PDP), and quartz crystals often used for light modulation. The induced phase differences between the light waves propagating in such crystals are found for the field orientations considered. 相似文献
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A. Peterman 《Physics letters. [Part B]》1982,114(5):333-336
An example of the explicit realization of the full renormalization group for physical quantities is investigated. It introduces two-index beta functions βij(gj): (i) the first index specifying the renormalization scheme chosen (including the scale μ); (ii) the second index specifying the coupling of which the appropriate beta function is the differential transformation. The treated example is presented in a 4 — ? dimensional O(n) massless (?·?)2 theory with emphasis on the calculation of the fixed point. 相似文献
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H. G. Dosch 《Physics letters. [Part B]》1986,180(4):390-394
The dimensionless parameter of the Skyrme lagrangian is evaluated by two methods. In one a combination of sum rules for the nucleon and the pion is used, in the other only baryonic sum rules. e = 5−8 and e = 5−7 is found, respectively, in agreement with the phenomenological value e = 5.45. To leading order in the operator-product expansion the analytical expression of e does not depend on the chiral-symmetry-breaking parameters. 相似文献
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Sergio Abbate Mariangela Gussoni Giuseppe Zerbi 《Journal of Molecular Spectroscopy》1978,73(3):415-429
This paper deals with the calculation of the intensities of Raman active fundamental vibrations of methane and its isotopical derivatives by the electrooptical theory of valence and with the “least squares” refinement of a set of electrooptical parameters from the experimental data. First some general considerations on the electrooptical theory of valence and on the computational method are presented. Then we give the expressions of the Raman intensities and depolarization ratios as functions of the electrooptical parameters and discuss some features of the “least squares” refinement technique. The results of our calculations on methane and deuteroderivatives are then reported. Particular attention has been given to the study of the type and combinations of parameters affecting each intensity. 相似文献
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为了精确识别电动汽车锂离子动力电池的关键状态参数,基于多孔电极理论和浓度理论,建立了一种考虑液相动力学行为的锂离子电池扩展单粒子模型.相较于传统单粒子模型,该模型增加了对负电极表面固体电解质界面膜参数的描述,并考虑了温度和液相浓度变化对锂离子电池关键参数的耦合影响.基于所建立的扩展单粒子模型,提出一种简化的参数灵敏度分析方法和有效的锂电池参数识别策略,用以确定特定工况下的高灵敏度待识别参数,进而利用遗传算法实现参数的优化求解.最后,通过对比分析本文模型和传统单粒子模型的仿真输出电压和相同工况下电池的实验输出电压验证了提出模型和参数识别方法的有效性和可行性,为电池管理系统的健康状态估计提供了理论基础. 相似文献
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Zhou Yu-fang Zhuang De-xin 《原子与分子物理学报》2004,21(Z1):319-322
Organic electrooptical (EO) chromophores are now gaining more attention because the property of organic photorefrative (PR) materials could be controlled by doped EO chromophores. In this paper, nonlinear optical (NLO) properties of a new group of organic electrooptical chromophores, synthesized recently in our laboratory, were elucidated theoretically with the quantum chemical density functional theory (DFT) and the intermediate neglect of differential overlap Hamilton and the configuration interaction (INDO/CI), as well as semiemperical Austin Model 1 (AM1) methods. The electronic transition intensity, dipole moment and the second- order polarizability were obtained. The results show this group of chrormophores possess appropriate optical absorption property and good electrooptical property and optical activity. The second-order polarizabilities βare as large as the order of 10-29 to 10-28 ESU, indicating the promising applications in the future. The physical mechanism of NLO is discussed by means of molecular orbital and electronic charge distribution. 相似文献