共查询到19条相似文献,搜索用时 515 毫秒
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研究了在三开口劈裂金属纳米环中,当入射场偏振方向不同时出现的多极局域表面等离激元共振现象及折射率传感特性。研究表明,当入射场偏振方向分别沿x 轴和y 轴时,在可见光-近红外区域分别激发起两个和三个明显的共振峰。通过改变缺口的张角,能够实现对共振峰位和强度的可控调整。共振峰位处劈裂纳米环的近场分布表明,LHA(左半弧)和DRHA(双右半弧)之间等离激元的杂化耦合是形成上述共振的原因。劈裂纳米环的多极共振非常适合折射率传感应用。当改变周围环境折射率,入射场沿x 轴偏振时,折射率敏感度的最大值可达到1365nm/RIU;入射场沿y 轴偏振时,折射率敏感度最大值可达2229nm/RIU。 相似文献
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用He—Ne激光在KNSBN晶体中实现高反射率自泵浦相位共轭 总被引:1,自引:1,他引:0
本文报道了用He-Ne激光在(K_(O.5)Na_(0.5)_2y(Sr_(0.61)B_(0.39)))_(1-y)Nb_2O_6(KNSBN)光折变晶体中实现高反射率自泵浦相位共轭,其共轭光的反射率高达40%.研究了共轭光反射率随入射角度变化的关系以及响应时间与入射光功率密度的关系. 相似文献
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光扇效应对Ce:KNSBN记录偏振组态的影响 总被引:5,自引:1,他引:4
在非同时读出条件下 ,采用Ar+ 5 14 .5nm单色激光为光源。以信号光为非寻常偏振光 (e光 ) ,通过改变抽运光的偏振态 ,研究不同写入光偏振组态下Ce∶KNSBN晶体的两波耦合特性。结果表明 :由于光扇效应的影响 ,信号光和抽运光同为e光时并非如预测的那样为最佳记录偏振组态。在信号光和抽运光与晶体表面法线呈θ =11°角对称入射下 ,当抽运光的偏振方向与e光偏振方向呈 30°角时 ,光扇噪声得到明显抑制 ,两波耦合增益最大。其原因是抽运光的o光分量对光扇散射光起到了非相干擦除 ,使两波有效耦合得到提高。 相似文献
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外腔共振是提高和频效率的有效方法. 实现外腔共振高效和频需要基频光高效地耦合到外部谐振腔中, 因此系统要达到阻抗匹配. 本文分别建立了双波长和单波长外腔共振和频系统的理论模型, 分析了腔增强因子与耦合腔镜反射率、入射基频光功率等参数的依赖关系, 通过数值模拟获得最优化的共振光耦合腔镜反射率, 使系统达到阻抗匹配, 提高和频效率. 研究表明, 无论双波长还是单波长外腔共振和频系统, 共振基频光的最佳耦合腔镜反射率只会随着另一束共振或者不共振的基频光入射功率的增加而减小, 而其本身的入射功率变化则影响较小; 进一步分析表明, 若共振基频光的耦合腔镜反射率超过阻抗匹配值, 和频光功率将会迅速减小, 而小于阻抗匹配值时, 和频光功率减少速度相对较慢, 因此实验过程中要尽量避免过耦合的情况出现. 本文的理论分析过程将对外腔和频实验有一定的指导意义. 相似文献
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非常偏振光在单轴晶体表面的反射-透射研究 总被引:8,自引:0,他引:8
为分析非常偏振光在晶体表面的能量损耗,给出一种求解反射率和透射率的方法,即根据电磁场的边值关系以及晶体的双折射和双反射现象,求解晶体光轴在入射面内时,非常偏振光从各向同性介质入射到晶体和从晶体出射到各向同性介质两种情况的反射率和透射率的方法,并给出反射率和透射率的解析解,同时得到对于晶体光轴在入射面内的情况,光轴的取向对非常偏振光反射率的大小几乎没有影响,但对产生全反射的临界角θc影响较大的结论。实验上用LiNbO3晶体验证了非常偏振光从各向同性介质入射到晶体时的反射率公式。求解方法简单实用,所给的表达式具有一般性,可以直接使用。 相似文献
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The optical reflectivity of (SN)x single crystals was measured in the visible region and the near infrared with light polarized parallel and perpendicular to the polymer chain axis. Whereas the reflectivity for light polarized perpendicular to the chain axis is approximately constant in this region, the reflectance for light polarized parallel to the chain axis exhibits a pronounced plasma edge at 2.72 eV. A simple Drude model was used to analyse the data. Differences between these results and those of previous film measurements are discussed. 相似文献
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The depolarization behavior of backscattered linearly polarized light from ZnO thin film was investigated experimentally. The results show that the characteristics are related to both the polarization orientation and wavelength of linearly polarized incident light. When the incident light is s-polarized, the depolarization behaviors are different for different wavelengths. When the incident light is p-polarized, the depolarization behaviors, on the contrary, are similar for different wavelengths. In addition, there is an optimal incident angle for depolarization of linearly polarized light with different wavelengths, which is equal to their effective Brewster angles, respectively. 相似文献
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M. Sallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,105(2):198-210
The problem of polarized radiation transfer in a finite plane-parallel binary Markovian random medium is studied. Pomraning-Eddington approximation is used for both the total intensity and the difference function of the polarized radiation. The formalism obtained by Levermore et al. and Pomraning is used to average the obtained solution in the deterministic case. The random medium is assumed to have specular-reflecting boundaries with angular-dependent externally incident flux. Numerical results of the average reflectivity and the average transmissivity are calculated for the different degrees of polarization. 相似文献
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A. V. Baryshev M. E. Dokukin A. M. Merzlikin M. Inoue 《Journal of Experimental and Theoretical Physics》2011,112(3):361-369
The interaction of linearly polarized light with photonic crystals based on bulk and thin-film synthetic opals is studied.
Experimental transmission spectra and spectra showing the polarization state of light transmitted through opals are discussed.
A change in polarization is found for waves experiencing Bragg diffraction from systems of crystallographic planes of the
opal lattice. It is shown that the polarization plane of the incident linearly polarized wave at the exit from photonic crystals
can be considerably rotated. In addition, incident linearly polarized light can be transformed to elliptically polarized light
with the turned major axis of the polarization ellipse. Analysis of polarization states of transmitted light by using the
transfer-matrix theory and homogenization theory revealed good agreement between calculated and experimental spectra. 相似文献
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For the transverse electric polarization case (TE) we present a treatment of the optical reflectivity and transmissivity of a slab whose dielectric coefficient is a real valued function of the light intensity. If this function is numerically integrable with respect to the light intensity, our treatment can serve as an algorithm for a numerical solution of the nonlinear wave equation. If the dielectric function is proportional to the intensity, an analytical solution of the cubic wave equation is given for the electric field strength and for the phase of the field in terms of Weierstrass' elliptic functions and first elliptic theta functions, respectively. Evaluating this solution by means of a computer algebra system yields the reflectivity, transmissivity and phase dependency on the incident field intensity and on parameters characteristic for the problem. Certain combinations of the parameters lead to bistable and multivalued behavior. The solution found is used to determine the relative extrema of the reflectivity and the critical values of the thickness and of the incident intensity. The results are a generalization of linear optics results. Application of the analysis to the cubic-quintic wave equation yields the general analytic solution which is used to detemine the reflectivity of a semi-infinite nonlinear medium. 相似文献
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J. Kroupa 《Optics Communications》1979,30(3):282-286
The formulae for reflectivity and transmissivity of monoclinic absorbing plane parallel crystal plate (of a specially chosen orientation) for normally incident light are derived. These are compared with usually used relations, which are exactly valid for higher symmetries. 相似文献
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Diffraction properties of four-petal Gaussian beams in uniaxially anisotropic crystal 总被引:1,自引:0,他引:1
Propagation properties of polarized four-petal Gaussian beams along the optical axis of uniaxially anisotropic crystals were investigated. Based on the paraxially vectorial theory of beam propagation, analytic expressions of the diffraction light field were obtained. The effects of the anisotropy on the polarization properties of the diffracted four-petal Gaussian beams have also been explained by numerical method. The results elucidate that the linear polarization state and the symmetry of the incident beams cannot be kept during propagation in anisotropic crystals. 相似文献
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Dielectric microspheres can confine light in a three-dimensional (3D) region called photonic nanojet is shown when they are illuminated by different polarized beams. The influence of incident light polarization on photonic nanojet using the finite-difference time-domain (FDTD) method is demostrated. The axial field intensity profiles of photonic nanojets for both the linear and circular polarization incident beams are very similar. Azimuthal polarization incident beam induces a doughnut beam along the optical axis, while the radial polarization incident beam permits one to reach an effective volume as small as 0.7(λ/n) 3 . 相似文献