电介质膜增强的Goos-Hnchen位移的微波测量

如果在折射率较高的电介质基底上镀一层折射率较低的电介质薄膜(介质膜的另一侧为折射率更低的介质,如空气),并且恰当选择基底内光束的入射角,使得光束在基底-介质膜界面上折射到薄膜内、在薄膜-空气界面上全反射,那么反射光束的Goos-Ha¨nchen(GH)位移在一定条件下会得到共振增强。采用微波技术直接地测量了这种Goos-Ha¨nchen位移随电介质膜厚度的变化,测量结果与理论预言吻合得较好。     

电介质膜增强的Goos—Hǎnchen位移的微波测量

如果在折射率较高的电介质基底上镀一层折射率较低的电介质薄膜（介质膜的另一侧为折射率更低的介质，如空气），并且恰当选择基底内光束的入射角，使得光束在基底一介质膜界面上折射到薄膜内、在薄膜一空气界面上全反射，那么反射光束的Goos—Hǎnchen（GH）位移在一定条件下会得到共振增强。采用微波技术直接地测量了这种Goos—Hǎnchen位移随电介质膜厚度的变化，测量结果与理论预言吻合得较好。     

有限光束穿过薄介质板的类Goos-H(a)nchen位移

研究了有限光束穿过薄介质板时透射光束存在类Goos-H(a)nchen位移、角偏转、束腰宽度的修正以及焦点的纵向移动4种非几何光学效应;给出了位移反向时入射角及介质板的厚度所需满足的必要条件;报道了利用微波技术首次在实验上观测到穿过薄介质板时波束的反向GHL位移.这些奇异的光学现象将在光学器件和集成光学中具有潜在的应用.     

基于液晶光阀和光束分析仪的Goos-H(a)nchen位移的简单测量

Goos-H(a)nchen(GH)位移只有波长数量级,在实验测量上比较困难.提出了一种基于液晶光阀(LCLV)和光束分析仪(LBP)直接测量GH位移的新方法.研究了LCLV对光偏振态调制的特性,结果发现,当外接电压发生变化时,光的偏振态也随之变化.利用LCLV对光偏振态的调制和LBP记录光斑的重心位置的变化,直接测量出TE和TM两种偏振态入射时棱镜单界面反射光束的GH位移差.这个探测方法简单,不需要复杂的外部处理电路,且实验结果与理论结果很吻合,此方法也可以进一步直接测量二维位移.     

含各向异性特异材料三明治结构的Goos-H主inchen位移研究

采用稳态相位法研究了正折射率材料/各向异性特异材料/金属三明治结构反射波的Goos-H(a)nchen (GH)位移.分别给出了在第一界面处发生全反射和部分反射情况下GH位移的解析表达式,并分析了含有4种不同类型特异材料三明治结构反射波产生GH位移的条件及GH位移的正负情况.通过数值计算系统研究了各向异性特异材料的光轴...     

光学薄膜减散射特性研究

为了降低光学薄膜的表面散射损耗,依据微粗糙面的一阶微扰理论,在不考虑多重散射效应的情况下,利用电磁场边界条件给出的光学薄膜任一界面粗糙度引起的散射场在入射介质中的表达式,重点讨论了单层光学薄膜实现零散射的条件以及实现减散射的条件,理论研究结果表明:当膜层的光学厚度为/4的偶数倍时,单层薄膜要实现减散射就必须使单层膜的折射率大于基底的折射率,且空气-薄膜界面的微粗糙度必须小于薄膜-基底界面之间的微粗糙度。当膜层的光学厚度为/4的奇数倍时,单层薄膜的折射率小于基底的折射率,且膜层两个界面的粗糙度必须满足特定条件,才能实现减散射的效果。     

古斯汉欣位移研究进展

本文通过K. Artmann的稳定位相理论对古斯汉欣(Goos-H?nchen,GH)位移进行了定性解释和定量分析;总结了国内外相关研究工作,介绍了GH位移在金属界面、介质光栅结构、多层金属包络结构、光子晶体材料、手性材料等界面理论研究和实验测量结果;综述了GH位移在不同波段特别是太赫兹波段的研究成果;GH位移的测量方法有直接测量和干涉测量2种,本文对此做了总结和解释;最后,以温度传感和浓度传感方面的研究结果为例介绍了GH位移的应用。     

薄膜增强的Goos-H(a)nchen位移

在单界面的全反射和双棱镜结构的受抑全内反射中,Goos-Hanchen(GH)位移量只能达到波长的量级,在实验中很难对其进行探测.在镀有薄膜的玻璃棱镜界面上,当入射角小于但接近于棱镜与薄膜(其折射率小于棱镜的折射率)界面的临界角时,全反射光束的GH位移共振增强现象.分析表明,在入射角给定的情况下,共振峰的峰值随着薄膜厚度的增加而增加,峰值位移量可以达到光波长的100～1000倍,且位移量可通过改变入射角和薄膜厚度来调节.最后给出了为使反射光束的轮廓不变,薄膜的厚度应满足的条件.     

含有银纳米膜的棱镜中光束古斯-汉欣位移效应研究

古斯-汉欣位移是一种灵敏度极高的折射率测量办法,在温度、压力传感等方面有 巨大的应用潜力, 但测量精度要求较高。为解决测量的困难和提高古斯-汉兴测量精度,本文设计了一种棱镜 -银纳米膜界面层, 搭建了一套可测量多偏振态多角度古斯-汉兴位移的测量装置,以此测量了棱镜-空气和棱 镜-银纳米膜不同 界面的光束的古斯-汉欣位移,并对其物理机制进行了探讨。实验结果显示棱镜-空气界面 的古斯-汉欣位移 平均值是2.7 μm,棱镜-银纳米膜界面的古斯-汉欣位移平均值是 27.7 μm,比棱镜-空气界面的位移增大了 约10倍。使用COMSOL multiphysics软件模拟了棱镜-银纳米膜以及 棱镜-空气界面的电场分布,对比棱镜- 空气的情况,表明在消逝场作用下,银纳米颗粒表面形成了较强光场分布,光场方向沿入射 光电场振动方 向;银颗粒表面光场和消逝场的叠加使得消逝场增强,从而导致棱镜-银纳米膜界面的古斯 -汉欣位移增大。 本工作为提高基于古斯-汉欣位移效应的生物传感器的灵敏度提供了一个可供选择的手段。     

含各向异性特异材料三明治结构的Goos-Hnchen位移研究

采用稳态相位法研究了正折射率材料/各向异性特异材料/金属三明治结构反射波的Goos-Hnchen(GH)位移.分别给出了在第一界面处发生全反射和部分反射情况下GH位移的解析表达式,并分析了含有4种不同类型特异材料三明治结构反射波产生GH位移的条件及GH位移的正负情况.通过数值计算系统研究了各向异性特异材料的光轴与界面的夹角α、入射角φ以及特异材料厚度d对GH位移的影响,计算结果与理论分析有很好的吻合.通过对特异材料结构中GH位移的研究,将有利于特异材料在微波或光学系统中的应用.     

Goos-Hänchen shift as a probe in evanescent slab waveguide sensors

The present paper deals with three-layer planar waveguide optical sensor. Different from the conventional slab waveguide sensors in which the effective refractive index of the propagating mode is taken to be the probe for detection changes in the analyte refractive index, we adopt Goos-Hänchen (GH) shift as the sensing probe for the proposed sensor. We show that the GH shift is strongly dependent on the refractive index of the cladding, thus it is a good candidate for detection changes in the analyte refractive index. We present and study the sensitivity of the GH shift at the cladding-film and substrate-film interfaces. It is found that GH shift has a high sensitivity and can be used for versatile optical slab waveguide sensors.     

The modified beam propagation method

A method is presented for the analysis of waveguide structures with abrupt index changes in both the transverse and axial directions. The method accurately includes the reflected fields and the Goos-Hanchen shift. The method can be extended to three-dimensional and graded index structures, and to include diffraction effects. For a graded index structure with no abrupt index changes the method reduces to the standard beam propagation method     

基于液晶光阀和光束分析仪的Goos-Hänchen位移的简单测量

提出一种基于液晶光阀（LCLV）和光束分析仪（LBP）直接测量Goos-Hänchen（GH）位移的新方法。在文中我们首先研究了LCLV对光偏振态调制的特性,结果发现,当控制电压发生变化时,光的偏振态也随之变化。然后利用LCLV对光偏振态的调制和LBP记录光斑的重心位置的变化,直接测量出TE和TM两种偏振态入射时棱镜单界面反射光束的GH位移差。这个探测方法简单,不需要复杂的外部处理电路,且实验结果与理论结果很吻合,这个方法也可以进一步直接测量二维位移。     

An Instrument to Measure Cutaneous Blood Flow Using the Doppler Shift of Laser Light

A system utilizing the Doppler shift of monochromatic laser light has been developed to measure blood flow in skin. Light from a low power (S mW) He-Ne laser is coupled into a quartz fiber and transmitted to the skin. This light is reflected from both the nonmoving tissues (reference beam) and moving red blood cells (Doppler shifted beam), received by a plastic fiber, and transmitted back to a photodiode where optical heterodyning occurs. The heterodyned output signal, which is proportional to the Doppler shift frequency, is amplified and both RMS and dc values obtained. The RMS value is weighted against the backscattered light intensity using the measured dc value as an index of total received power. This is used as the output flow velocity value.     

高斯光束通过猫眼逆反射器的变换特性

运用矩阵光学对高斯光束通过猫眼逆反射器的传输变换进行了理论推导,并对猫眼逆反射器后向反射光特性进行了分析.研究表明,当入射光腰与猫眼逆反射器的距离不同时,选取合理的正离焦量可以得到比输入高斯光束发散角更小的反射光束.     

含Rashba自旋轨道耦合二维电子气结构中电子反常位移及自旋分离

研究了含Rashba自旋轨道耦合的磁电调制半导体二维电子气中弹道电子的反常位移 （Goos-H?nchen位移,即GH位移）。计算中发现,通过调节结构的各个参数包括入射角、磁场强度和Rashba自旋轨道耦合系数,可以有效地调控GH位移,并且在一定条件下可以为负。电子的GH位移和自旋极化态有密切关系,这个自旋相关的位移可以用来分离不同自旋极化的电子束。基于这种现象,提出了一种利用GH位移在半导体2DEG中分离不同自旋极化电子的方法。     

Evanescent fields produced by totally reflected beams

When the coordinates of a line source are assigned complex values in the free-space Green's function, the resulting field represents a bounded beam. This property is employed to formulate an integral expression for the field transmitted across a plane dielectric interface. Asymptotic evaluation of the integral requires detailed study of the saddle point and steepest descent path configurations, especially when the incident beam is totally reflected. The asymptotic results in that case are employed to chart the power flow lines and to deduce the lateral shift of the reflected beam.     

Reflection z-scan for measuring the nonlinear refractive index of porous silicon

An experimental investigation on the nonlinear refractive index of nanoporous silicon at wavelengths of 532 nm and 1064 nm is reported by the reflection z-scan(RZ-scan) method with picosecond pulses.The porous silicon(PS) does not need to be peeled from silicon substrate.The method uses a p-polarized beam with oblique incidence.The modification of the reflected beam intensity gives the information of the surface nonlinear refractive index.The index of porous silicon at 1064 nm is at the same order of magnit...     

Millimeter wave beams diffracted from reflecting gratings

According to the angular-spectrum method, a radiation beam of an antenna horn in the Fresnal region is decomposed into the plane waves with the fast Fourier transform algorithm and the waves diffracted from a reflection grating are superposed as a diffracted beam. Compared with the reflected beam from the same size mirror, the radiation half width of the diffracted beam from a grating is narrower and its lateral shape is shift. These performances have been experimentally verified at Ka-band by: (1). The relative diffraction efficiencies in the first order with two triangular gratings which is put along propagating direction of a beam produced by a conical lens-horn. (2). H-plane lateral width with power—3dB lapsed of the focus beam from a grating and a mirror in a grating spectrometer for millimeter waves (25–100 GHz).     

Three-dimensional Gaussian beam reflection from short-circuitedisotropic ferrite slab

The plane wave spectrum analysis is extended to the study of three-dimensional Gaussian beam propagation and scattering. The reflection of a three-dimensional circular Gaussian beam from a parallel-sided ferrite slab, backed by a ground plane, is then investigated. The beam field is represented by an angular continuous spectrum of plane waves. Using the Fresnel reflection coefficients of the short-circuited slab for both perpendicular and parallel polarizations, a paraxial approximation for the reflected beam field is derived. It is found that after reflection from the short-circuited slab, the circular Gaussian beam becomes, in general, an elliptical Gaussian beam, and the beam axis is displaced from the position predicted by ray optics. For the thin slab case, approximate formulas for the phase center difference and the lateral shift are determined. The relevance of these results to a new method of ferrite measurement is explained