相位物体Z-扫描研究金属簇合物[Tp*W(μ3-S)3Cu3Py3(μ3-Br)](PF6)/DMF溶液的瞬态热致非线性折射

在纳秒时域,采用相位物体(PO)Z-扫描技术研究了一种新型金属簇合物溶液的瞬态热致非线性效应.该方法的最大优点是很容易区分瞬态热致非线性折射和三阶非线性折射.本文利用PO Z-扫描和传统Z-扫描研究了在8 ns脉宽、不同能量激光脉冲作用下[Tp*W(μ3-S)3Cu3Py3(μ3-Br)](PF6)/DMF溶液的光学非线性.从声波方程和热传导方程出发,对实验结果进行了理论分析和数值模拟,理论值和实验结果很好的吻合.研究结果表明,样品溶液的非线性折射主要来源于瞬态热致非线性效应.     

相位物体$lt;i$gt;Z$lt;/i$gt;-扫描研究金属簇合物［$lt;i$gt;Tp$lt;/i$gt;*W($lt;i$gt;μ$lt;/i$gt;$lt;sub$gt;3$lt;/sub$gt;-S)$lt;sub$gt;3$lt;/sub$gt;Cu$lt;sub$gt;3$lt;/sub$gt;$lt;i$gt;Py$lt;/i$gt;$lt;sub$gt;3$lt;/sub$gt;($lt;i$gt;μ$lt;/i$gt;$lt;sub$gt;3$lt;/sub$gt;-Br)］($lt;i$gt;PF$lt;/i$gt;$lt;sub$gt;6$lt;/sub$gt;)/DMF溶液的瞬态热致非线性折射

在纳秒时域,采用相位物体（PO）Z-扫描技术研究了一种新型金属簇合物溶液的瞬态热致非线性效应.该方法的最大优点是很容易区分瞬态热致非线性折射和三阶非线性折射.本文利用PO Z-扫描和传统Z-扫描研究了在8 ns脉宽、不同能量激光脉冲作用下［Tp*W（μ₃-S）₃Cu₃Py₃（μ₃-Br）］（PF₆）/DMF溶液的光学非线性.从声波方程和热传导方程出发,对实验结果进行了理论分析和数值模拟,理论值和实验结果很好的吻合.研究结果表明,样品溶液的非线性折射主要来源于瞬态热致非线性效应. 关键词： Z-扫描')" href="#">相位物体 Z-扫描 瞬态热致非线性折射 光克尔效应 DMF     

几种新型金属配合物热致三阶非线性光学特性

利用连续激光Z-扫描方法研究了过渡金属Ni、Cu、Pd的新型有机配合物的热致三阶非线性光学特性。结果表明：在488nm和632．8nm波长连续激光激发下,这几种配合物的光学非线性折射主要来源于热效应。并由实验曲线计算了它们的热光系数dn／dT及热致非线性折射率n2。通过比较,发现热致非线性折射率与配合物分子结构、激发波长及在该波长下的线性吸收强弱有关。金属中心原子的原子序数越大,热光系数和折射率也相应的越大。在488nm波长激光激发下的dn／dT和n2大于该配合物在632．8nm波长激发下的dn／dT和n2,在同一波长下,化合物溶液在该波长下的吸收越强,其dn／dT和n2值也越大。     

金属有机配合物的热致非线性光学特性的对比研究

利用连续激光z扫描技术研究了两种新型金属有机配合物非线性材料在457nm、488nm和514nm三个激发波长下的热光效应。结合实验曲线和理论公式计算了这两种配合物溶液的热光系数dn/dT和热致非线性折射率n2的值。通过对比研究发现,材料的热致三阶非线性光学性质依赖于材料的分子结构和激发波长,Cu配合物的热光系数和热致非线性折射率的数值较大,且受激发波长的变化影响很小,而Pd配合物的热致非线性随激发波长的增大而减小,这主要是由两种化合物分子结构的差异导致其吸收光谱分布不同决定的。     

生物大分子杂化处理的CdSe/ZnS核/壳量子点多层膜的超快三阶非线性研究

利用静电自组装技术，以生物大分子材料壳聚糖杂化处理具有稳定结构的CdSe/ZnS核/壳量子点，形成复合多层薄膜. 与薄膜的吸收谱线比较，在375nm飞秒激光激发下测量的量子点的光致发光谱存在Stokes位移. 采用Z扫描技术，利用790nm飞秒激光研究了其三阶非线性吸收和折射特性，发现饱和吸收信号来自CdSe/ZnS量子点，而自聚焦的折射信号则部分来自壳聚糖. 测出多层膜的三阶非线性系数分别是β＝6.5×10^-6cm/W，n₂＝1.5×10^-10cm²/W. 关键词： CdSe/ZnS量子点 非线性性能 光致发光谱     

热Fock态下量子效应对介观左手传输线负折射系数的影响

基于热场动力学理论研究了热Fock态下量子效应对介观左手传输线微波段负折射系数的影响.结果表明:负折射系数随电流涨落的增加表现出线性递增的特点,而随温度的升高、频率的增大表现出锐减特性;负折射系数的变化幅度受光子数调控.该结论可对基于左手传输线开发的微波器件的微型化、集成化研究提供参考.     

团簇WOS3Cu3I(2-MePy)3激发态非线性光学性质

用Z扫描方法测量了团簇WOS3Cu3I(2 MePy) 3对 5 32nm、8ns激光脉冲的非线性光学响应曲线。以速率方程为基础对实验结果进行拟合 ,理论计算和实验结果符合得很好。应用激发态折射理论研究了非线性折射率系数的符号变化和折射度比值Kr 的关系 ,Kr>1时非线性折射率系数为正 ,Kr<1时折射率系数为负。     

GaAs在光通讯波段的超快非线性光学研究

采用Z-扫描和泵浦-探测技术,在光通讯波段对砷化镓(GaAs)单晶进行了非线性动力学以及非线性光学的实验研究.飞秒泵浦-探测实验结果表明,三阶非线性光学效应源于砷化镓单晶对飞秒激光的瞬态双光子吸收,而五阶非线性光学效应源于砷化镓单晶双光子吸收诱导的自由载流子吸收效应.通过Z扫描实验,得到了关于GaAs单晶所有的非线性光学参数,包括双光子吸收系数、三阶非线性折射系数、双光子吸收诱导的自由载流子吸收截面以及双光子吸收诱导的自由载流子折射截面.结果表明,砷化镓单晶在制造光限幅器件和光电探测器方面具有良好的发展前景.     

双臂相位Z扫描测量稀溶液中溶质光学非线性

基于相位Z扫描技术提出了双臂相位Z扫描技术,在相位Z扫描技术的光路中并联一个相同的光路。与传统的Z扫描技术相比,相位Z扫描可区分溶液的三阶非线性折射和瞬态热致非线性,且可实现单脉冲测量,系统灵敏度也要比Z扫描技术高。以往的方法都不能很好地测量稀溶剂中纯溶质的光学非线性,采用双臂相位Z扫描技术可极大提高系统测量信噪比,从而可准确地测量出稀溶剂中纯溶质的光学非线性。     

Z—扫描技术及其应用

文章介绍了Ｚ－扫描技术的原理、特点及其应用，分析了单色Ｚ－扫描法测量非线性折射系数和非线性吸收系数，以及双色Ｚ－扫描法研究非简并非线性光学效应．     

Polarization controlled couplings of surface plasmon with asymmetrical nanoslit pairs

Light-driven surface plasmons offer an opportunity to ultrafast information processing combining the compactness of electric circuits with the bandwidth of photonic networks. For practical applications, the efficient and controllable conversion from signal light to surface plasmons is essential. This leads to the recent developments in the polarization controlled couplings of surface plasmons. Currently, most works only tailor the orientation and arrangement of nanoslits to control the launching of surface plasmons. In this paper, we consider both the orientation and size of each slit in a one-dimensional array of nanoslit dimers. We first realize the unidirectional propagation of surface plasmons with designed wavefronts. Next, the unidirectional coupling and bi-directional coupling of surface plasmons are realized for a pair of orthogonal polarizations, respectively. This is quite different from the conventional opposite propagating surface plasmons excited by two orthogonal polarizations. The manipulation of both orientation and size of nanoslits allows additional freedom in the photon-plasmon conversions.     

Surface plasmons in a free-electron metal

The dispersion and damping of the surface plasmons are calculated for a free-electron model of Al. At large wave-vector the frequency of the surface plasmons approaches that of the bulk plasmons. Their damping remains quite small up to a wave-vector close to the bulk plasmon cut-off. The change in zero-point energy of the plasmons is calculated, and it gives a large positive contribution to the surface energy.     

Tunable On‐Chip Sources with Aperiodic Metasurface

Surface plasmons show tremendous capability in integrated communication, quantum computing and sensing. Excitations and manipulations of surface plasmons are essential in developing integrated photonic devices. Here, a systematic study of tunable emission of surface plasmons with an eightfold quasicrystal metasurface, which acts as an on‐chip source, is presented. It is shown that the quasicrystal structure can switch on or off the surface plasmons propagation channels in the desired direction. Meanwhile, such a quasicrystal structure can be polarization‐dependent or polarization‐independent based on different constituent slit pairs. The proposed quasicrystal design provides more freedom for steering surface plasmons in the launching process. Thus, it may significantly simplify the design and fabrication of integrated plasmonic devices.     

Optical V(z) for high-resolution 2pi surface plasmon microscopy

Surface plasmons are electromagnetic surface waves whose k vectors are greater than that of free-space radiation. We excite surface plasmons by using an oil-immersion lens, which forms one arm of an interferometer. We demonstrate the way in which the characteristic output variation with defocus is determined by the propagation properties of the surface plasmons, which leads to diffraction-limited surface plasmon microscopy in the far field.     

Resonant surface plasmons of a metal nanosphere treated as propagating surface plasmons

On the assumption that the resonant surface plasmons on a spherical nanoparticle are formed by standing waves of two counter-propagating surface plasmon waves along the surface, by using Mie theory simulation, we find that the dispersions of surface plasmon resonant modes supported by silver nanospheres match with those of the surface plasmons on a semiinfinite medium-silver interface very well. This suggests that the resonant surface plasmons of a metal nanosphere can be treated as a propagating surface plasmon wave.     

Refractive and reflective behavior of polymer prisms used for surface plasmon guidance

Two-dimensional optics with surface plasmons was realized by the use of topographically structured dielectric polymer coatings. Triangles of polymethylmetacrylate (PMMA) with lateral dimensions of some tens of micrometers on top of a silver layer act as two-dimensional prisms for surface plasmons. Refraction and internal reflection of plasmons were investigated by scanning near-field optical microscopy. The change in propagation direction can be explained by Snell's law when taking an effective refractive index for plasmons into account. Furthermore, intensity modulations in the PMMA elements and in the transmitted plasmon beam were observed.     

Dispersive Fourier-transform spectroscopy of surface plasmons in the infrared frequency range

The optical scheme and the principle of operation of an asymmetric Mach-Zehnder interferometer for dispersive spectroscopy of surface IR plasmons are discussed. A thin-layer sample deposited on a conducting substrate, which guides surface plasmons, is placed in one of the arms of the interferometer. This makes it possible, by applying a complete Fourier transform to the interferogram, to obtain the spectrum of the complex refractive index of surface plasmons and, therefore, of the complex dielectric permittivity of the sample or the substrate material.     

Band gaps in the spectra of terahertz surface plasmons on metallic diffraction gratings

The effect of the appearance of band gaps in the energy spectra of terahertz surface plasmons has been experimentally observed and investigated. The band gaps are formed due to the interference interaction of the surface plasmons excited by pulsed terahertz radiation on metallic diffraction gratings. It has been shown that the experimental dispersion curves of terahertz plasmons are in good agreement with the dispersion curves obtained in the numerical simulation.     

Plasma resonance radiation from non radiative plasmons

Non radiative surface plasmons decay into photons on a rough surface. This light emission is studied with gold- and silver foils of different thicknesses. The surface plasmons are excited in this experiment by light. By this way a relatively accurate determination of the optical constants is possible.     

The observation of the localized surface plasmons and its coupling

The surface plasmons properties on gold film composed of inverted square pyramidal pits were investigated. The near‐field scanning optical microscopy image showed that the surface plasmons were mainly located in the cavity of the pits; this is consistent with the mapping image obtained using the Raman scattering intensity of Rhodamine 6G. The calculation results obtained by using the finite element method showed that the electric field mainly located in the pyramidal pits and the field distribution was not affected by the adjacent pits around it. Compared with the single pyramidal pit, the localized electric field intensity increased in the condition of the structure array because of the surface plasmons coupling effect. The surface‐enhanced Raman scattering spectra intensity decreased as the incident angle of the excited laser increased except that there are two peaks at around 5° and 17.5°, which can be attributed to the Bragg scattering of the surface plasmons. The reflectance spectra collected by a microscope at different magnifications were different. The intensity variation between surface‐enhanced Raman scattering spectra obtained using ×20 and ×50 objective illustrated that the adsorption peak in the reflectance spectra corresponded to the surface plasmons coupling effect. Copyright © 2011 John Wiley & Sons, Ltd.