用扫描近场光学显微镜技术研究金膜表面等离体子共振

表面等离体子波(SPW)可与入射光横磁波极化能量耦合并被共振激发,这种现象被称为表面等离体子共振现象(SPR)。主要利用扫描近场光学显微镜(SNOM)技术和表面等离体子共振现象技术相结合,来研究金膜表面等离体子共振。设计并建立了结构独特的新型Kretschmann型表面等离体子共振现象耦合装置,同时又设计了具有厚度梯度的表面等离体子的制备方法。在此基础上,测量了改变入射角条件下的表面等离体子共振曲线,测得该装置的等离体子共振角灵敏度为1°。并且对金膜表面进行表面等离体子共振条件下的扫描近场光学显微成像。实验结果表明,在共振时金膜表面的扫描成像比不共振时清晰,而且增加了很多细节。应用表面等离体子共振现象技术将可以明显提高扫描近场光学显微镜的信噪比、分辨力等性能。

Resonant Effects of FPL and SPP for Light Transmitting through Subwavelength Metallic Gratings

A new model is proposed to explain the physical mechanism of the extraordinary transmission enhancement in subwavelength metallic grating.The extraordinary transmission enhancement is described by the co-operation of Fabry-Perot-like(FPL) resonance and the surface plasmon polariton(SPP) resonance.The rigorous coupled-wave analysis(RCWA) and the finite difference time domain(FDTD) method are employed to illustrate the model by calculating the transmission and the field distributions in the subwavelength metallic grating,respectively.And the numerical calculations show that transmission enhancement is achieved when the coupling resonance of the incident light,the surface plasmon polariton mode and the Fabry-Perot-Like mode is happened,which are in good agreement with the proposed model.

Quasi-stationary planetary wave-mean flow interactions in the Northern Hemisphere stratosphere and their responses to ENSO events

Based on the ERA-40 reanalysis data from the European Centre for Medium-Range Weather Forecasts and the output of ECHAM5/MPI-OM, this study investigated the interactions between the quasi-stationary planetary wave （SPW） and mean flow, and their responses to E1 Nifio-Southern Oscillation （ENSO） events in the northern hemispheric stratosphere. Results show that the activity of SPW is the strongest in winter, when the SPW propagates along the polar waveguide into the stratosphere and along the low-latitude waveguide to the subtropical tropopause. The analysis of three dimensional SPW structure indicates that the main sources of SPW activity are located over the Eurasian continent and the North Pacific north of 45°N. On the one hand, the two waveguides of the SPW reflect the influence of mean flow on the propagation of the SPW. On the other hand, the upward propagating SPW can interact with the stratospheric mean flow, leading to deceleration of the zonal mean westerly. Furthermore, the SPW exhibits clear responses to ENSO events. During E1 Nifio winters, the SPW in the strat- osphere tends to propagate more upward and poleward. Its interactions with mean flow can induce a dipole pattern in zonal mean zonal winds, with accelerated westerly winds at low-middle latitudes and decelerated westerly winds at high latitudes. The ECHAM5/MPI-OM model reproduces the climatology of the SPW well. Although the simulated SPW is slightly weaker than the observations in the stratosphere, the model＇s performance has significant improvements compared with other GCMs used in previous studies. However, there are still some problems in the responses of the SPW to ENSO in the model. Although the model reproduces the responses of both the amplitude and the SPW-mean flow interactions to ENSO well in the troposphere, the stratospheric responses are quite weak. Therefore, further studies are needed to improve the simulation of the stratospheric atmospheric circulation and related dynamical processes.

Description of squeezed surface plasmons

Surface plasmon polaritons (SPPs) are the combined electron oscillations and electromagnetic waves propagating along the interface between a conductor and a dielectric. Recently Huck et al. [Huck A, et al. Phys Rev Lett, 2009, 102: 246802] proved that SPPs can be in a squeezed state, and the squeezed surface plasmons can propagate in a gold waveguide. In this paper, we introduce a quantum mechanical description of the squeezed surface plasmons at first, and discuss the influence of the waveguide losses on the squeezed surface plasmons.

Dust-Lower-Hybrid Surface Waves in Classical and Degenerate Plasmas

The dispersion relation for general dust low frequency electrostatic surface waves propagating on an interface between a magnetized dusty plasma region and a vacuum is derived by using specular reflection boundary conditions both in classical and quantum regimes. The frequency limit ω ≤ωei ≤ ωce is considered and the dispersion relation for the Dust-Lower-Hybrid Surface Waves （DLHSW＇s） is derived for both classical and quantum plasma half-space and analyzed numerically. It is shown that the wave behavior changes as the quantum nature of the problem is considered.

Surface plasmon interference pattern on the surface of a silver-clad planar waveguide as a sub-micron lithography tool

A new sub-micron photolithography tool has been realized by utilizing the interference of surface plasmon waves(SPWs) on the near surface of a silver(Ag)-clad ultraviolet(UV) planar waveguide.A laser beam with a wavelength of 325 nm was incident into the waveguide core,and suffered a series of total internal reflections on the interfaces between the waveguide core and the cladding layers.The incident light and the reflected light induced two beams of SPWs traveling in contrary directions,which interfered with each other and formed a standing wave as a sub-micron photolithography tool.A near-field scanning optical microscope(NSOM) was employed to measure the intensity distribution of the stationary wave field of the near surface of the Ag layer of the waveguide,anastomosed with theoretical values acquired by use of finite difference time domain(FDTD) simulations.And with this sub-micron photolithography tool a SMG with a period of 79.3 nm,in good agreement with the theoretical value of 80.1 nm,was inscribed on the surface of a self-processing hybrid SiO2/ZrO2 solgel film for the first time.

Excitation of Propagating Plasmons in Semi-Infinite Graphene Layer by Free Space Photons

By investigating the diffraction of plane waves by a semi-infinite solution for propagating surface plasmons in graphene, which can be excited graphene edge. The theoretical results are confirmed by numerical simulations. excite propagating surface plasmons in graphene where the graphene edge plays graphene layer, we present a rigorous by incident plane waves through the Our results reveal a convenient way to an important role.

Electrostatic Surface Waves on Semi-Bounded Quantum Electron-Hole Semiconductor Plasmas

The electrostatic surface waves on semi-bounded quantum electron-hole semiconductor plasmas are studied within the framework of the quantum hydrodynamic model, including the electrons and holes quantum recoil effects,quantum statistical pressures of the plasma species, as well as exchange and correlation effects. The dispersion characteristics of surface electrostatic oscillations are investigated by using the typical values of Ga As, Ga Sb and Ga N semiconductors. Numerical results show the existence of one low-frequency branch due to the mass difference between the electrons and holes in addition to one high-frequency branch due to charge-separation effects.