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单轴晶体中光轴任意取向时寻常光与非常光间的离散 总被引:19,自引:4,他引:15
晶体器件(特别是非线性光学器件)的性能与晶体内o光与e光的离散有很大的关系。详细讨论了光在晶体表面折射时,对于任意光轴取向、任意入射角情况,如何确定o光与e光的离散。借助于转动晶体的方法,形象地描绘出e光相对o光的离散曲线。当入射角较大时,离散曲线的形状 随光轴取向变化很大:从简单的圆或椭圆到复杂的双闭合曲线。理论计算与实验结果很好地吻合。 相似文献
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大口径KDP/DKDP晶体在强紫外光辐照下产生横向受激拉曼散射效应(TSRS), 受激放大的拉曼散射光将导致激光能量损失甚至激光损伤, 测量DKDP晶体TSRS增益系数对设置激光装置的运行区间以确保晶体的安全使用非常重要。采用高精度光谱仪探测大口径DKDP晶体(氘含量65%)在351 nm激光辐照下的横向拉曼散射信号, 得到了拉曼散射光的增长曲线, 拟合得到的拉曼增益系数为0.109 cm/GW。同时, 实验结果表明晶体体损伤不影响TSRS增长行为, 表明晶体体损伤对拉曼增益系数测量结果的影响可以忽略。 相似文献
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CCD(电荷耦合器件)图象传感器是一种高灵敏度摄象器件。如果把 CCD 图象传感器冷却,或用纤维光学把象增强器和 CCD 耦合,或 CCD 以电子轰击方式工作,均可获得良好的微光性能。本文报导了国外各种微光CCID(电荷耦合成象器件)和 CCD—TV 摄象机的研制水平和使用情况. 相似文献
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大口径KDP/DKDP晶体在强紫外光辐照下产生横向受激拉曼散射效应(TSRS), 受激放大的拉曼散射光将导致激光能量损失甚至激光损伤, 测量DKDP晶体TSRS增益系数对设置激光装置的运行区间以确保晶体的安全使用非常重要。采用高精度光谱仪探测大口径DKDP晶体(氘含量65%)在351 nm激光辐照下的横向拉曼散射信号, 得到了拉曼散射光的增长曲线, 拟合得到的拉曼增益系数为0.109 cm/GW。同时, 实验结果表明晶体体损伤不影响TSRS增长行为, 表明晶体体损伤对拉曼增益系数测量结果的影响可以忽略。 相似文献
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本文主要介绍固体摄象器件的现状、特点、功能、应用电路及应用领域。一、固体摄象器件的现状固体摄象器件目前主要有OCD、MOS、CPD三种类型。MOS器件现已大量进入市场,主要优点是没有惰性,动态范围大,彩色混色小。缺点是灵敏度和分辨率不及CCD的。 OCD器件是固体摄象器件的主流。其优 相似文献
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Carlos J. Zapata-Rodríguez David Pastor María T. Caballero Juan J. Miret 《Optics Communications》2012,285(16):3358-3362
We show that subwavelength diffracted wave fields may be managed inside multilayered plasmonic devices to achieve ultra-resolving lensing. For that purpose we first transform both homogeneous waves and a broad band of evanescent waves into propagating Bloch modes by means of a metal/dielectric (MD) superlattice. Beam spreading is subsequently compensated by means of negative refraction in a plasmon-induced anisotropic medium that is cemented behind. A precise design of the superlens doublet may lead to nearly aberration-free images with subwavelength resolution in spite of using optical paths longer than a wavelength. 相似文献
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基于位函数的引入与介质参量无关,将各向异性目标内外的电场展为级数形式,得到了任意各向异性目标n阶散射场、目标内场的递推表达式,给出了介电常量张量的变换关系,在平面波任意入射的条件下,并给出了传播单位矢量与极化单位矢量的一般关系.以磁化冷等离子体为例,给出了一阶散射场的具体表达式,并对二阶散射场引起的误差进行了评估.在THz波段和光波段,对所得结果进行了部分仿真.结果表明:微分散射对电波频率和极化状态等因素的影响较为敏感,介电常量张量的非对角元素对散射的影响不大,当波长与目标尺寸一定时,仿真结果不仅适用于THz波段,对其它波段也成立. 相似文献
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基于位函数的引入与介质参量无关,将各向异性目标内外的电场展为级数形式,得到了任意各向异性目标n阶散射场、目标内场的递推表达式,给出了介电常量张量的变换关系,在平面波任意入射的条件下,并给出了传播单位矢量与极化单位矢量的一般关系.以磁化冷等离子体为例,给出了一阶散射场的具体表达式,并对二阶散射场引起的误差进行了评估.在THz波段和光波段,对所得结果进行了部分仿真.结果表明:微分散射对电波频率和极化状态等因素的影响较为敏感,介电常量张量的非对角元素对散射的影响不大,当波长与目标尺寸一定时,仿真结果不仅适用于THz波段,对其它波段也成立. 相似文献
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The reflection of linearly polarized light from an ultrathin anisotropic dielectric film on isotropic absorbing substrate is investigated analytically in the long-wavelength limit. All analytical results are correlated with the numerical solution of the anisotropic reflection problem on the basis of rigorous electromagnetic theory. Simple analytical approach developed in this work not only gives a physical insight into the reflection problem but also provides a way of estimating the necessary experimental accuracy for optical diagnostics by reflection characteristics. It is shown that obtained expressions are of immediate interest for determining the parameters of anisotropic surface layers. Innovative possibilities for optical diagnostics of anisotropic properties of ultrathin dielectric layers upon absorbing materials are discussed. 相似文献
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运用微扰法研究平面波入射分层介质粗糙面的光波透射问题,推出了不同极化状态的透射光波散射系数公式。采用高斯粗糙面来模拟实际的分层介质粗糙面,结合高斯粗糙面的功率谱导出了平面波入射高斯分层介质粗糙面的透射系数计算公式。通过数值计算得到HH极化透射系数随透射光波散射角变化的曲线,讨论底层介质介电常数、中间介质介电常数和厚度、粗糙面参数及入射光波长对透射系数的影响。数值计算结果表明:底层介质介电常数、中间介质介电常数和厚度、粗糙面参数及入射光波长对透射系数的影响是非常复杂的。 相似文献
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F.J. García-Vidal J.M. Pitarke 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(2):257-265
Optical-absorption cross-sections and energy-loss spectra of aligned multishell carbon nanotubes are investigated, on the
basis of photonic band-structure calculations. A local graphite-like dielectric tensor is assigned to every point of the tubules,
and the effective transverse dielectric function of the composite is computed by solving Maxwell's equations in media with
tensor-like dielectric functions. A Maxwell-Garnett-like approach appropriate to the case of infinitely long anisotropic tubules
is also developed. Our full calculations indicate that the experimentally measured macroscopic dielectric function of carbon
nanotube materials is the result of a strong electromagnetic coupling between the tubes. An analysis of the electric-field
pattern associated with this coupling is presented, showing that in the close-packed regime the incident radiation excites
a very localized tangential surface plasmon.
Received 18 January 2001 相似文献
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P. Kopperschmidt 《Applied physics. B, Lasers and optics》2001,73(7):717-720
Electrically induced birefringence is studied in photonic bi-oriented crystals in terms of molding lightflow in optical devices.
In photonic bi-oriented crystals, misorientation of dielectric anisotropic grains results in a dielectric contrast at the
grain boundaries. The translational periodicity of the optical constants depends upon a regular network of twisted dielectrics.
Due to the anisotropy of the bicrystalline structure the direction of light propagation determines the dielectric contrast
at the grain boundaries. In a specific crystallographic arrangement the optical properties of the bi-oriented crystal can
be tuned by the electro-optical effect: the periodic dielectric contrast is electrically induced and photonic bandgaps are
generated by applying external electric fields. The geometrical requirements for tunable photonic bicrystals are evaluated
based on materials employed for electro-optical applications. Tunable photonic bi-oriented crystals may be candidates for
fast optical switches, modulators and multiplexers in the optical communication network.
Received: 5 July 2001 / Revised version: 3 August 2001 / Published online: 15 October 2001 相似文献
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I.I. Smolyaninov J. Elliott G. Wurtz A.V. Zayats C.C. Davis 《Applied physics. B, Lasers and optics》2006,84(1-2):253-256
The use of photonic crystal and negative refractive index materials is known to improve the resolution of optical microscopy
and lithography devices down to the 80 nm level. Here we demonstrate that utilization of well-known digital image recovery
techniques allows us to further improve the resolution of optical microscopy down to the 30 nm level. Our microscope is based
on a flat dielectric mirror deposited onto an array of nanoholes in thin gold film. This two-dimensional photonic crystal
mirror may have either a positive or negative effective refractive index as perceived by surface plasmon polartions in the
visible frequency range. The optical images formed by the mirror are enhanced using simple digital filters.
PACS 73.20.Mf; 42.70.Qs; 07.60.Pb 相似文献
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A novel plasmonic nanolens formed by a tapered subwavelength metal slit surrounded by surface dielectric gratings is proposed and demonstrated numerically. By patterning surface corrugations on the output surface, the beam can be focused, by regulating the aperture, the focal length can be controlled effectively. Numerical simulations using Finite-Difference Time-Domain (FDTD) method coupled with anisotropic perfectly matched layer (APML) boundary conditions verify that the proposed metallic lens can focus the radiation on the scale of a wavelength below the substrate and the method is effective for the design of nano-optical devices such as optical microprobes. 相似文献