共查询到20条相似文献,搜索用时 31 毫秒
1.
F. Formanek Y. De Wilde L. Aigouy W. K. Kwok L. Paulius Y. Chen 《Superlattices and Microstructures》2004,35(3-6):315
We have used a home-made apertureless near-field scanning optical microscope (ANSOM) for mapping nanometric steps between SiC and gold regions under visible (λ=655 nm) and infrared (λ=10.6 μm) illumination. The images, obtained with a signal demodulation at the tip oscillation frequency and at higher harmonics, clearly show optical contrasts with a subwavelength resolution of about 30 nm. Other images recorded in the visible on a YBa2Cu3O7 crystal indicate that the tip used in our experiments is able to reveal polarization effects. We also present a near-field thermal optical microscope (NTOM) which operates without any external illumination. In this new kind of microscope, the laser source which is usually used to excite the evanescent waves, is replaced by a simple heating of the sample. The electromagnetic radiation locally scattered by the tip comes from the thermal radiation. Our results with this new technique prove a 200 nm lateral resolution. 相似文献
2.
Gómez-Santos G 《Physical review letters》2003,90(7):077401
The time evolution of evanescent modes in Pendry's perfect lens proposal for ideally lossless and homogeneous, left-handed materials is analyzed. We show that time development of subwavelength resolution exhibits universal features, independent of model details. This is due to the unavoidable near degeneracy of surface electromagnetic modes in the deep subwavelength region. By means of a mechanical analog, it is shown that an intrinsic time scale (missed in stationary studies) has to be associated with any desired lateral resolution. A time-dependent cutoff length emerges, removing the problem of divergences claimed to invalidate Pendry's proposal. 相似文献
3.
Imaging enhancement of a photonic crystal superlens due to a surface mode with a specific dispersion
Yifeng Shen Fangfang Wu Yongchun Wang Lulu Li Changqing Guo 《Photonics and Nanostructures》2012,10(4):485-492
We study the imaging process for a photonic crystal slab lens with a surface defect by the finite-difference-time-domain (FDTD) method. We demonstrate an odd surface mode with a specific dispersion curve in this system. The dispersion curve has an extreme point, which is corresponding to a slow light. If the working frequency is chosen at this extreme point the subwavelength resolution of image will be enhanced. Moreover, the subwavelength resolution of image is very sensitive to the position of this extreme point in the dispersion diagram. Longer interaction time and better field distribution may give a qualitative physical understanding for the enhancement of imaging quality. 相似文献
4.
A planar metamaterial structure consisting of two layers of split-ring resonator (SRR) arrays is demonstrated to form the
image of a point source with subwavelength resolution. The source frequency is swept through the resonance gap of the metamaterial
layers and the lateral field intensity distribution is recorded on the transmission side of the metamaterial. When the source
is tuned to the resonance frequency of SRRs, the metamaterial acts as a high permeability medium and a distinct image with
subwavelength resolution in the lateral direction is obtained. Increasing the distance between the individual SRR layers reduces
the interlayer coupling, and the intensity and spatial resolution of the image decrease rapidly. 相似文献
5.
Controlling the phase delay of light transmitted through double-layer metallic subwavelength slit arrays 总被引:1,自引:0,他引:1
Marcet Z Paster JW Carr DW Bower JE Cirelli RA Klemens F Mansfield WM Miner JF Pai CS Chan HB 《Optics letters》2008,33(13):1410-1412
We demonstrate that the phase of light transmitted through double-layer subwavelength metallic slit arrays can be controlled through lateral shift of the two layers. Our samples consist of two aluminum layers, each of which contains an array of subwavelength slits. The two layers are placed in sufficient proximity to allow coupling of the evanescent fields at resonance. By changing the lateral shift between the layers from zero to half the period, the phase of the transmitted electromagnetic field is increased by pi, while the transmitted intensity remains high. Such a controllable phase delay could open new capabilities for nanophotonic devices that cannot be achieved with single-layer structures. 相似文献
6.
In this Letter we investigate the subwavelength imaging of a three-dimensional plasmon superlens based on the full vector wave simulations of optical wave propagation and transmission. The optical transfer functions are computed. Comparisons are made between the results of lenses with flat and periodic/random rough surfaces. We also study the problem of practical imaging system geometry using laser as an illumination source. Results show that the lens with periodic or random roughness can reduce the field interference effects, and provide improved focus on the transmission field and the Poynting flux. We illustrate that the subwavelength roughness in a plasmon lens can enhance the image resolution over a flat lens for both matched and unmatched permittivity conditions. The enhancement of resolution occurs because the introduced subwavelength roughness can amplify the evanescent wave components and suppress the surface plasmon resonance peaks. 相似文献
7.
Lu Z Murakowski JA Schuetz CA Shi S Schneider GJ Prather DW 《Physical review letters》2005,95(15):153901
We experimentally demonstrate subwavelength resolution imaging at microwave frequencies by a three-dimensional (3D) photonic-crystal flat lens using full 3D negative refraction. The photonic crystal was fabricated in a layer-by-layer process. A subwavelength pinhole source and a dipole detector were employed for the measurement. By point-by-point scanning, we obtained the image of the pinhole source shown in both amplitude and phase, which demonstrated the imaging mechanism and subwavelength feature size in all three dimensions. An image of two pinhole sources with subwavelength spacing showed two resolved spots, which further verified subwavelength resolution. 相似文献
8.
We demonstrate the possibility to use near field optics to perform two-dimensional dopant profiling on silicon surface, with deep submicron spatial resolution. The sample surface is contacted by an aqueous electrolyte giving a reverse biased junction that is illuminated by a subwavelength optical source, in near filed conditions. A staircase calibration structure was used with several boron-doped layers with either 4 μm or 0.4 μm thickness and doping between 1017 and 1020 at/cm3. Measurements were performed on the sample cross section. It is shown that photocurrent surface mapping shows up the doped areas with a lateral resolution better than 100 nm. 相似文献
9.
Photoluminescence (PL) spectroscopy with subwavelength lateral resolution has been employed to probe individual localization centers in a thin InGaN/GaN quantum well. Spectrally narrow emission lines with a linewidth as small as 0.8 meV can be resolved, originating from the recombination of an electron-hole pair occupying a single localized state. Surprisingly, the individual emission lines show a pronounced blueshift when raising the temperature, while virtually no energy shift occurs for increasing excitation density. These findings are in remarkable contrast to the behavior usually found in macro-PL measurements and give a fundamental new insight into the recombination process in semiconductor nanostructures in the presence of localization and strong internal electric fields. We find clear indications for a biexciton state with a negative binding energy of about -5+/-0.7 meV. 相似文献
10.
Chernomyrdin N. V. Kucheryavenko A. S. Rimskaya E. N. Dolganova I. N. Zhelnov V. A. Karalkin P. A. Gryadunova A. A. Reshetov I. V. Lavrukhin D. V. Ponomarev D. S. Karasik V. E. Zaytsev K. I. 《Optics and Spectroscopy》2019,126(5):560-567
Optics and Spectroscopy - We propose a new method of terahertz microscopy for imaging of biological tissues with a subwavelength spatial resolution. It makes it possible to surmount the Abbe... 相似文献
11.
Anton A. Kolesnikov Yurii E. Lozovik Svetlana P. Merkulova 《Journal of Russian Laser Research》2010,31(5):469-474
We propose a new method of laser spectroscopy, which combines high subwavelength space resolution, high sensitivity, and spectral resolution. The method is based on using a fiber laser near the generation threshold instead of a fiber optical near-field microscope. The near-field subwavelength aperture in the “active” fiber is employed for probing. Absorption on the objects under consideration (atoms, molecules, nanostructure, etc.) leads to the failure of oscillations in the fiber laser. We make a computer simulation of the system under consideration and analyze the method’s sensitivity. 相似文献
12.
Chan HB Marcet Z Woo K Tanner DB Carr DW Bower JE Cirelli RA Ferry E Klemens F Miner J Pai CS Taylor JA 《Optics letters》2006,31(4):516-518
We present measurements of transmission of infrared radiation through double-layer metallic grating structures. Each metal layer contains an array of subwavelength slits and supports transmission resonance in the absence of the other layer. The two metal layers are fabricated in close proximity to allow coupling of the evanescent field on individual layers. The transmission of the double layer is found to be surprisingly large at particular wavelengths, even when no direct line of sight exists through the structure as a result of the lateral shifts between the two layers. We perform numerical simulations using rigorous coupled wave analysis to explain the strong dependence of the peak transmission on the lateral shift between the metal layers. 相似文献
13.
Thiel C Bastin T Martin J Solano E von Zanthier J Agarwal GS 《Physical review letters》2007,99(13):133603
We propose a technique to obtain subwavelength resolution in quantum imaging with potentially 100% contrast using incoherent light. Our method requires neither path-entangled number states nor multiphoton absorption. The scheme makes use of N photons spontaneously emitted by N atoms and registered by N detectors. It is shown that for coincident detection at particular detector positions a resolution of lambda/N can be achieved. 相似文献
14.
We propose and demonstrate the feasibility of a new microscopic technique, which is based on variable coherence illumination. By manipulating the spatial coherence properties of an incident evanescent field, subwavelength resolution is achieved over a large field of view from far-field intensity measurements. 相似文献
15.
We propose a half-cylindrical hyperlens with symmetrical metallodielectric structure which consists of five periods of the
symmetrical GaP/Ag/GaP films. Such hyperlens can transfer subwavelength information to the output surface (about one wavelength)
due to the flat dispersion. Compared with the half-cylindrical hyperlens composed of the resonant Ag/GaP structure, the symmetrical
GaP/Ag/GaP metallodielectric structure shows higher transmission and resolution for the propagating waves and evanescent waves,
which is also confirmed by the transfer matrix method. In addition, subwavelength imaging can be realized when the incident
wavelength varies from 550 nm to 650 nm. 相似文献
16.
We investigated a far-field superlens operating at mid-infrared wavelength that allows resolving subwavelength features in
the far-field. By utilizing evanescent enhancement provided by surface plasmon excitation of silver nanorods and Moiré effect,
we numerically demonstrated that subwavelength information of an object can be converted to propagating information. This
information can then be captured by conventional optical components. A simple image reconstruction algorithm can restore the
subwavelength object. A sub-diffraction-limited resolution of 2.5 μm at 6-μm wavelength is demonstrated. 相似文献
17.
银金属在特定波长范围内的负折射率性质可以放大倏逝波,在近场成像中能够保留次波长信息,因此是制造"完美透镜"的优良材料。由银金属和其他介质组成的复合材料能够通过其调整体积分数来改变"完美透镜"的工作波长,使其在可见光和近红外范围内实现完美成像。除体积分数外,复合材料中金属颗粒的大小和形状也会对透镜的工作波长和成像质量有影响。在考虑尺寸效应修正的基础上,通过分析尺寸对成像性质的影响发现:减小金属颗粒尺寸会使工作波长发生蓝移,当银颗粒尺寸减小到10nm时,会显著降低成像质量。 相似文献
18.
Ki Young Kim Boyang Liu Yingyan Huang Seng-Tiong Ho 《Optical and Quantum Electronics》2008,40(5-6):343-347
Simulation of detecting photoelectrons using multi-level multi-electron (MLME) finite-difference time-domain (FDTD) method with an application to near-field subwavelength imaging based on semiconductor nanophotodetector (NPD) array is reported. The photocurrents from the photodiode pixels are obtained to explore the resolution of this novel NPD device for subwavelength imaging. One limiting factor of the NPD device is the optical power coupling between adjacent detector pixels. We investigate such power coupling in the presence of absorbing media as well as the spatial distributions of the electric field and photoelectron density using the MLME FDTD simulation. Our results show that the detection resolution is about one tenth of the operating wavelength, which is comparable to that of a near-field scanning optical microscope based on metal clad tapered fiber. 相似文献
19.
Kulchin YN Vitrik OB Kuchmizhak AA Pustovalov EV Nepomnyashchii AV 《Optics letters》2011,36(19):3945-3947
We investigate numerically and experimentally the possibility of development of a cavity-based probe for near-field optical microscopy systems based on a fiber Fabry-Perot interferometer with a subwavelength protruding aperture. It was shown that the probe provides a spatial resolution of no worse than λ/37 for λ=1550 nm. 相似文献
20.
We present a novel method for the formation of a complete depolarizer that is based on a polarization-state scrambling procedure over the space domain. Such an element can be achieved by use of cascaded, computer-generated, space-variant subwavelength dielectric gratings. We introduce a theoretical analysis and experimentally demonstrate a depolarizer for infrared radiation at a wavelength of 10.6 microm. 相似文献