共查询到20条相似文献,搜索用时 0 毫秒
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V. S. Volkov S. I. Bozhevolnyi K. Leosson† & A. Boltasseva‡ 《Journal of microscopy》2003,210(3):324-329
Surface plasmon polaritons (SPPs) propagation at a gold film surface covered by periodic arrays of ~40‐nm‐high scatterers arranged in a triangular lattice of different periods containing straight line defects is studied using collection scanning near‐field optical microscopy. The results reveal the dependence of the SPP band gap (SPPBG) effect manifested via the SPP reflection and guiding (along line defects) on the parameters of the surface structures (period, filling factor and lattice orientation). We find that the SPPBG effect is stronger along ΓK direction for all investigated periodic structures. Our results demonstrate that the SPPBG effect becomes less pronounced with a decrease of the filling factor and disappears for a filling factor close to 0.2. We also observe that the centre of the SPPBG shifts towards longer wavelengths with an increase of the lattice period. 相似文献
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S. I. Bozhevolnyi 《Journal of microscopy》2001,202(2):313-319
Using the general approach to image formation in collection near-field optical microscopy, I derive the symmetry relations for the amplitude coupling coefficients in the case of a weakly guiding single-mode fibre terminated with a probe tip possessing axial symmetry. It is shown that, for the symmetrical detection configuration, six elements of the coupling matrix can be expressed by using only three independent coupling coefficients. The obtained relations are further applied to describe near-field mapping of surface plasmon polariton (SPP) fields. I demonstrate that, for the symmetrical detection configuration, the near-field optical image reflects the intensity distribution of the SPP field components parallel to the surface plane, even though the strong perpendicular component is also being detected. This conclusion is supported with numerical simulations that elucidate the influence of symmetry of the fibre probe on the resulting near-field optical image. The near-field optical images simulated for scattering systems typical for SPP microoptics and localization are presented. It is found that the presence of asymmetry in the detection configuration increases the contribution of the perpendicular field component and results in the images approaching the corresponding SPP intensity distributions. 相似文献
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表面等离子体激元透镜设计及其数值计算 总被引:1,自引:0,他引:1
提出了一种新的表面等离子体激元透镜的设计方案,该方案通过在两个亚波长小孔的外表面放置电介质光栅实现对入射光束的有效会聚。利用遗传算法研究了波导中表面等离子体激元的色散关系,结果表明,通过调节亚波长小孔的宽度和介电常数可以有效地调控有效折射率,从而实现对亚波长金属平板波导结构中表面等离子体激元传播特性的调控。利用时域有限差分方法(FDTD)结合完美匹配层(PML)边界条件数值模拟了此结构中的光场分布,讨论了光栅周期数对成像特性的影响,从而深入理解了纳米聚焦效应的物理机制。结果显示,随着表面光栅数的增多,焦距和焦斑大小都在增加。光栅数从5增加至11时,焦距由1.715μm增大至2.325μm,焦斑大小由0.615μm增大至1.715μm,这一结构有可能被用作未来集成光路中的纳米聚焦器件。 相似文献
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The optical wave behaviour around a subwavelength aperture in a thick metallic screen is examined through three‐dimensional computer simulation. Treating the metallic screen as a dielectric slab with complex‐valued permittivity, it is possible to design an aperture that simultaneously provides high intensity and small spot size through the excitation of surface plasmon polaritons on the side walls of the aperture. 相似文献
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A prism coupling arrangement is used to excite surface plasmons at the surface of a thin silver film and a photon scanning tunnelling microscope is used to detect the evane-scent field above the silver surface. Excitation of the silver/air mode of interest is performed at λ1 = 632.8 nm using a tightly focused beam, while the control of the tip is effected by exciting a counter-propagating surface plasmon field at a different wavelength, λ2 = 543.5 nm, using an unfocused beam covering a macroscopic area. Propagation of the red surface plasmon is evidenced by an exponential tail extending away from the launch site, but this feature is abruptly truncated if the surface plasmon encounters the edge of the silver film — there is no specularly reflected 'beam'. Importantly, the radiative decay of the surface mode at the film edge is observable only at larger tip–sample separations, emphasizing the importance of accessing the mesoscopic regime. 相似文献
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为增强基于Ag膜光纤表面等离子体共振(SPR)传感器的抗氧化能力,可将Au膜镀于Ag膜表面。利用TFCalc软件对不同厚度Ag膜和Au-Ag复合膜的光纤SPR传感特性进行理论仿真研究。仿真结果表明:光纤SPR吸收峰显著依赖于Ag膜厚度,当Ag膜厚度由40nm逐渐增加到80nm时,共振吸收峰的半峰全宽逐渐减小,且共振波长随Ag膜厚度的增大而减小,共振波长变化范围较小,仅为7nm左右;Au膜的引入对共振吸收峰反射率影响不大,不同厚度Au-Ag复合膜的SPR共振波长随Au膜厚度的增大而增大。 相似文献
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待测介质折射率对光纤SPR光谱的特性研究 总被引:1,自引:1,他引:0
为提高光纤传感器的灵敏度和检测精度,达到精确测量的目的。基于表面等离子体共振(SPR)理论及TFCalc软件,仿真研究光纤表面等离子体共振传感器的反射光谱特性,考查待测介质折射率在一定范围内变化对反射光谱特性的影响。研究结果表明,当入射角一定时,表面等离子体共振的最佳膜厚随待测介质折射率的减小而减小;当膜厚和入射角度不变时,表面等离子体共振波长随待测介质折射率的减小向短波长方向移动。共振吸收峰随待测介质折射率的减小移动的距离越小,且逐渐变窄,传感器的灵敏度逐渐提高。 相似文献
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T. Niwa Y. Mitsuoka K. Kato S. Ichihara N. Chiba M. Shin-Ogi K. Nakajima H. Muramatsu & T. Sakuhara 《Journal of microscopy》1999,194(2-3):388-392
We develop a novel optical microcantilever for scanning near-field optical microscopy controlled by atomic force mode (SNOM/AFM). The optical microcantilever has the bent channel waveguide, the corner of which acts as aperture with a large tip angle. The resonance frequency of the optical microcantilever is 9 kHz, and the spring constant is estimated to be 0.59 N/m. The optical microcantilever can be operated in contact mode of SNOM/AFM and we obtain the optical resolution of about 200 nm, which is as same size as the diameter of aperture. We confirm that the throughput of optical microcantilever with an aperture of 170 nm diameter would be improved to be more than 10−5 . 相似文献
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表面等离子波是指在金属和介质表面传播的电磁波,在垂直界面方向上呈指数衰减,提出了一种棱镜结构用以耦合出由K retschm ann结构产生的表面等离子波,使反射、吸收能量转化为透射光。棱镜结构在数值模拟中可以被简化为多层介质结构,利用传输矩阵方法模拟了高斯光束入射到这种结构中的传播情况,形象地得到了产生表面等离子体共振和表面等离子波耦合的结果。模拟结果显示提出的棱镜结构达到了接近70%的耦合效率,可以应用于偏振分光器件;并且利用这种结构还可观察到高斯光束分裂现象。 相似文献
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G. MeYer T. CreCelius A. BaUer D. WeGner I. MaUch & G. KaIndl 《Journal of microscopy》2003,210(3):209-213
In this study, guiding of surface plasmon polaritons excited at a gold film surface along corrugation‐free channels in regions that are covered with randomly located surface scatterers, is considered using near‐field microscopy for imaging of surface plasmon polariton intensity distributions at the surface. In the wavelength range 713–815 nm, we observed complete inhibition of the surface plasmon polariton propagation inside the random structures composed of individual (≈ 70 nm high) gold bumps (and their clusters) placed on a 55 nm thick gold film with a bump density of 75 µm?2. We demonstrate well‐defined surface plasmon polariton guiding along corrugation‐free 2 µm wide channels in random structures and, in the wavelength range 738–774 nm, low‐loss guiding around 20° bends having a bend radius of ≈ 15 µm. 相似文献
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H.-J. Maas J. Heimel H. Fuchs U. C. Fischer J. C. Weeber† & A. Dereux† 《Journal of microscopy》2003,209(3):241-248
Scanning near‐field optical microscopy images of metal nanostructures taken with the tetrahedral tip (T‐tip) show a distribution of dark and bright spots at distances in the order of 25–50 nm. The images are interpreted as photonic nanopatterns defined as calculated scanning near‐field optical microscopy images using a dipole serving as a light‐emitting scanning near‐field optical microscopy probe. Changing from a positive to a negative value of the dielectric function of a sample leads to the partition of one spot into several spots in the photonic nanopatterns, indicating the excitation of surface plasmons of a wavelength in the order of 50–100 nm in metal nanostructures. 相似文献
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Imaging of optical disc using reflection-mode scattering-type scanning near-field optical microscopy
M. Yamaguchi Y. Sasaki H. Sasaki T. Konada Y. Horikawa A. Ebina T. Umezawa & T. Horiguchi 《Journal of microscopy》1999,194(2-3):552-557
A phase-change optical disc was observed using a reflection-mode scattering-type scanning near-field optical microscope (RS-SNOM). In an a.c.-mode SNOM image, the 1.2 μm × 0.6 μm recording marks were successfully observed although the data were recorded on the groove. In contrast, no recording marks could be resolved in a d.c.-mode SNOM image. These results are in good agreement with those from a numerical simulation using the finite difference time domain method. The resolution was better than 100 nm with a.c.-mode SNOM operation and the results indicate that recording marks in phase-change optical media can be directly observed with the RS-SNOM. 相似文献
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We studied a nanometre-sized optical probe in a scanning near-field optical microscope. The probe profile is determined by using a knife-edge method and a modulated transfer function evaluation method which uses nanometre-sized line-and-space tungsten patterns (with spaces 1 μm to 50 nm apart) on SiO2 substrates. The aluminium-covered, pipette-pulled fibre probe used here has two optical probes: one with a large diameter (350 nm) and the other with a small diameter (10 nm). The small-diameter probe has an optical intensity ≈63 times larger than that of the large-diameter probe, but the power is about 1/25 of that of the large probe. 相似文献