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Search for "near-field" in Full Text gives 98 result(s) in Beilstein Journal of Nanotechnology.
Optical near-fields & nearfield optics
Beilstein J. Nanotechnol. 2014, 5, 186–187, doi:10.3762/bjnano.5.19
- -field in the vicinity of nanostructures. In this Thematic Series, various examples for the use of optical near-fields and near-field optics are presented. Metallic nanostructures, especially noble metals such as gold and silver, are efficient for nano-focusing and controlling light on the nanoscale
- , because they support surface plasmons, i.e., collective excitations of the electron gas, which couple strongly to light. As a result, the optical near-field around such plasmonic structures can be enhanced by orders of magnitude compared to the incident light intensity, and can be localized in “hot spots
- ” with a length of a few nanometers. This effect of strong near-field enhancement around sharp structures of noble metals has been known from Surface Enhanced Raman Scattering (SERS) for a long time [1]. Yet, the well-controlled tailoring of nanostructures necessary to quantitatively control the optical
Dye-doped spheres with plasmonic semi-shells: Lasing modes and scattering at realistic gain levels
Beilstein J. Nanotechnol. 2013, 4, 974–987, doi:10.3762/bjnano.4.110
- Nikita Arnold Boyang Ding Calin Hrelescu Thomas A. Klar Institute of Applied Physics, Johannes Kepler University, 4040 Linz, Austria 10.3762/bjnano.4.110 Abstract We numerically simulate the compensation of absorption, the near-field enhancement as well as the differential far-field scattering
- orientation of the electric field vector. In a recent experimental work, some of the most prominent eigenmodes of metallic voids have been imaged using a near-field microscope [14]. A further prominent feature of semi-shells with broken symmetry (compared to angularly symmetric shells) is their capability to
- incident plane wave. The images are cut in the x–z plane, i.e., the plane spanned by the k-vector (z-axis) and the polarization of the electric field (x-axis). A three dimensional representation of the near field enhancement just outside the semi-shell structure is given on the lower left of both panels
Challenges in realizing ultraflat materials surfaces
Beilstein J. Nanotechnol. 2013, 4, 875–885, doi:10.3762/bjnano.4.99
- nanophotonics in the next section. Optical near field: dressed photon–phonon Near-field optics has made it possible to reduce the size of photonic devices to the sub-wavelength scale or smaller [17]. In particular, nanoscale photonic devices such as AND-gates, NOT-gates, and focusing devices have been developed
- that utilize the optical near field generated in nanoscale semiconductor quantum structures and the dipole-forbidden near-field energy transfer. Moreover, near-field optics has been used to fabricate nanoscale structures beyond the diffraction limit of light. For example, photolithography has been used
- equipment involved is large and expensive [19]. Thus, with further development, near-field lithography will be able to satisfy the requirements of future semiconductor electronic devices, such as highly integrated DRAMs. The physics of these nanoscale optics has been developed under the assumption of a
Probing the plasmonic near-field by one- and two-photon excited surface enhanced Raman scattering
Beilstein J. Nanotechnol. 2013, 4, 834–842, doi:10.3762/bjnano.4.94
- particularly also for optical spectroscopy. Surface enhanced Raman signatures of single molecules can provide us with important information about the optical near-field. We discuss one- and two-photon excited surface enhanced Raman scattering at the level of single molecules as a tool for probing the plasmonic
- near-field of silver nanoaggregates. The experiments reveal enhancement factors of local fields in the hottest hot spots of the near-field and their dependence on the photon energy. Also, the number of the hottest spots and their approximate geometrical size are found. Near-field amplitudes in the
- hottest spots can be enhanced by three orders of magnitudes. Nanoaggregates of 100 nm dimensions provide one hot spot on this highest enhancement level where the enhancement is confined within less than 1nm dimension. The near-field enhancement in the hottest spots increases with decreasing photon energy
Controlling the near-field excitation of nano-antennas with phase-change materials
Beilstein J. Nanotechnol. 2013, 4, 632–637, doi:10.3762/bjnano.4.70
- the landscape of the plasmonic system at a step resolution of λ/20. These findings introduce a new approach for nano-circuitry, bio-assay addressing and imaging applications. Keywords: light localization; nano-antenna; near field; phase-change materials; plasmon coupling; Introduction With the rapid
- interference where an isolated energy hot-spot can be created and positioned at an appointed location in a confined area through the active control of light illumination on nanohole arrays with optimized amplitudes and phases [1]. With other methods, it is also possible to control the near-field excitation of
- plasmonic resonators placed on a thin film of phase-change material can be selectively excited, generating isolated near-field energy hot-spots with selective excitation under a monochromatic plane wave illumination. Unlike other proposed techniques, our method for energy hot-spot positioning is based on a
k-space imaging of the eigenmodes of sharp gold tapers for scanning near-field optical microscopy
Beilstein J. Nanotechnol. 2013, 4, 603–610, doi:10.3762/bjnano.4.67
- Abstract We investigate the radiation patterns of sharp conical gold tapers, which were designed as adiabatic nanofocusing probes for scanning near-field optical microscopy (SNOM). Field calculations show that only the lowest order eigenmode of such a taper can reach the very apex and thus induce the
- generation of strongly enhanced near-field signals. Higher-order modes are coupled into the far field at finite distances from the apex. Here, we demonstrate experimentally how to distinguish and separate between the lowest and higher-order eigenmodes of such a metallic taper by filtering in the spatial
- frequency domain. Our approach has the potential to considerably improve the signal-to-background ratio in spectroscopic experiments at the nanoscale. Keywords: adiabatic nanofocusing; Fourier optics; metallic wire modes; plasmonics; scanning near-field optical microscopy (SNOM); Introduction Metallic
Mapping of plasmonic resonances in nanotriangles
Beilstein J. Nanotechnol. 2013, 4, 588–602, doi:10.3762/bjnano.4.66
- a wavelength of 800 nm, which excited higher order plasmon modes in these triangles. The ablation distribution as well as the local melting of small parts of the nanostructures reflect the regions of large near-field enhancement. The observed patterns are reproduced in great detail by FDTD
- for the field enhancement are typically somewhat smaller than the calculated ones. The results demonstrate the caveats for FDTD simulations and the potential and the limitations of “near field photography” by local ablation and melting for the mapping of complex plasmon fields and their applications
- . Keywords: ablation; FDTD simulations; field enhancement; nanotriangles; near field; surface plasmons; Introduction Considering classical optics, light cannot be focused to a scale much smaller than half its wavelength. This phenomenon, commonly known as “diffraction limit”, represents a major obstacle in
3D nano-structures for laser nano-manipulation
Beilstein J. Nanotechnol. 2013, 4, 534–541, doi:10.3762/bjnano.4.62
- to be a trapping force of 2 pN/W/μm2 (numerical result) exerted on a 50-nm diameter bead in water. The simulations were based on the analytical Lorentz force model. Keywords: extraordinary transmission; near field; optical tweezing; plasmonics; reactive ion etching; self-induced back-action
Apertureless scanning near-field optical microscopy of sparsely labeled tobacco mosaic viruses and the intermediate filament desmin
Beilstein J. Nanotechnol. 2013, 4, 510–516, doi:10.3762/bjnano.4.60
- illuminated AFM cantilever tip apex exposes strongly confined non-propagating electromagnetic fields that can serve as a coupling agent for single dye molecules. Thus, combining both techniques by means of apertureless scanning near-field optical microscopy (aSNOM) enables concurrent high resolution
- are fluorescently labeled to a low degree. The simultaneous recording of topography and fluorescence data allows for the exact localization of distinct building blocks within the superordinate structures. Keywords: apertureless scanning near-field optical microscope; atomic force microscopy
- ; fluorescence microscopy; Introduction Scanning near-field optical microscopy (SNOM) provides sub-wavelength optical resolution [1]. The sample is excited by the strongly confined near-field at the tip apex, which is induced by the dipolar coupling between the incident light and the probe. Moreover, coupling
Femtosecond-resolved ablation dynamics of Si in the near field of a small dielectric particle
Beilstein J. Nanotechnol. 2013, 4, 501–509, doi:10.3762/bjnano.4.59
- “Rocasolano”, CSIC, Serrano 119, 28006 Madrid, Spain 10.3762/bjnano.4.59 Abstract In this work we analyze the ablation dynamics of crystalline Si in the intense near field generated by a small dielectric particle located at the material surface when being irradiated with an infrared femtosecond laser pulse
- material response at ordinary and large peak power densities enabling a direct comparison between both scenarios. The time resolved images of near field exposed regions are consistent with a remarkable temporal shift of the ablation onset which occurs in the sub-picosend regime, from about 500 to 800 fs
- after excitation. Keywords: crystalline Si; fs-resolved microscopy; laser ablation; near-field enhancement; ultrafast dynamics; Introduction The term “near field optics” is used to describe the phenomena associated to non-propagating and highly localized electromagnetic fields and their interaction
Near-field effects and energy transfer in hybrid metal-oxide nanostructures
Beilstein J. Nanotechnol. 2013, 4, 306–317, doi:10.3762/bjnano.4.34
- the absorption, especially in thin-film structures, as well as the exploitation of field enhancements in the near-field region. Another approach reviewed in [6] for “light trapping” in photovoltaics is the excitation of surface plasmon polaritons at the interface between metals and semiconductors
- . These studies will be reported in section D. On the other hand, the actual intensity distribution in the near field of the nanoantennas will depend not only on the size and thickness of the antennas, but also on the dielectric properties of its environment, i.e., both the substrate and the nanophosphor
Plasmonic oligomers in cylindrical vector light beams
Beilstein J. Nanotechnol. 2013, 4, 57–65, doi:10.3762/bjnano.4.6
- characterized by linear optical spectroscopy. The well characterized and designed structures are afterwards studied in depth by exciting them with radial and azimuthally polarized light and simultaneously measuring their plasmonic near-field behavior. Additionally, we attempt to model and simulate our results
- , a project which has, to the best of our knowledge, not been attempted so far. Keywords: near-field microscopy; oligomers; plasmons; radial and azimuthal polarization; Introduction Plasmonics is the optics of metal nanoparticles. If an external light field impinges on a metal nanoparticle
- derived the necessary prerequisites for the efficient launch of magnetic plasmon propagation. In our experiments we utilized high-resolution electron-beam lithography for the fabrication of the nanostructures. In order to study the excitation of magnetic modes we used a home-built combined near-field
Characterization and properties of micro- and nanowires of controlled size, composition, and geometry fabricated by electrodeposition and ion-track technology
Beilstein J. Nanotechnol. 2012, 3, 860–883, doi:10.3762/bjnano.3.97
Controlled positioning of nanoparticles on a micrometer scale
Beilstein J. Nanotechnol. 2012, 3, 773–777, doi:10.3762/bjnano.3.86
- through a thiol-group. To suppress interactions between nanoparticles or the molecules bound to them, usually interparticle distances of 50 nm are sufficient (for a recent study on near-field effects around a single dot see [27]). To guarantee single particle/molecule spectroscopy significantly larger
Assessing the plasmonics of gold nano-triangles with higher order laser modes
Beilstein J. Nanotechnol. 2012, 3, 674–683, doi:10.3762/bjnano.3.77
- laser modes; localised surface plasmons; near field; surface-enhanced Raman scattering; Introduction The interaction of light and matter is especially intriguing in those cases where the size of the matter particle is comparable to or smaller than the wavelength of the light. When illuminating metallic
- study called plasmonics. In addition, such particle plasmons yield an evanescent electromagnetic field at the outline of the nano-particles. This so-called near field can be highly enhanced and strongly confined in space. So far, the near field at the outline of nano-particles in general [2] and nano
- ], photopolymerisation [6] and near-field ablation [3][10][11] have been performed. It was found that the material of the triangles plays a distinct role [9], as do the triangles' edge length and height [3][8][10][11] and the material of the underlying substrate [12]. Additionally, nano-particles and nano-particle
Combining nanoscale manipulation with macroscale relocation of single quantum dots
Beilstein J. Nanotechnol. 2012, 3, 324–328, doi:10.3762/bjnano.3.36
- resolution comparable to the length scale of the system of interest, however, continues to present a challenge. A number of techniques have been developed to push the resolution of optical microscopy and spectroscopy to the single-molecule/particle limit. These include scanning near-field optical microscopy
Nano-FTIR chemical mapping of minerals in biological materials
Beilstein J. Nanotechnol. 2012, 3, 312–323, doi:10.3762/bjnano.3.35
- microscopy provide information about the shapes of nanoparticles; however, all of these methods fail on chemical recognition. Neither do they allow local identification of mineral type. We demonstrate that infrared near-field microscopy solves these requirements at 20 nm spatial resolution, highlighting, in
- its first application to natural nanostructures, the mineral particles in shell and bone. "Nano-FTIR" spectral images result from Fourier-transform infrared (FTIR) spectroscopy combined with scattering scanning near-field optical microscopy (s-SNOM). On polished sections of Mytilus edulis shells we
- osteopathies. Keywords: biomineralization; chemical mapping; infrared spectroscopy; nanocrystals; optical near-field microscopy; Introduction Fourier-transform infrared spectroscopy (FTIR) [1] is a standard tool in chemical analysis. It can identify virtually any substance through the "fingerprint" of the
Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications
Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94
- used, or otherwise one may imprint water-based ink patterns on the SAMs, which will prevent the photocatalytic degradation of the shadowed area [60]. Instead of exposure through a mask, one may “write” with a well-collimated beam of UV radiation, for example by using an UV laser, or by near-field
Distance dependence of near-field fluorescence enhancement and quenching of single quantum dots
Beilstein J. Nanotechnol. 2011, 2, 645–652, doi:10.3762/bjnano.2.68
- fluorescence emission I for arbitrary but constant Γexc was calculated. The normalized intensity of the electric field distribution propagating in the lower glass half-space was integrated over a sphere (Equation 4). To rule out the contribution of the nonpropagating near-field, the sphere radius was set to R
Towards multiple readout application of plasmonic arrays
Beilstein J. Nanotechnol. 2011, 2, 501–508, doi:10.3762/bjnano.2.54
- fluorescence enhancement was detected for distances in the range of 3–7 nm, whereas for shorter distances the molecular fluorescence was quenched [28]. Since the plasmonic behavior of a SPM probe for tip-enhanced near-field optical microscopy is comparable with that of a single metallic nanoparticle, the usage
Nanophotonics, nano-optics and nanospectroscopy
Beilstein J. Nanotechnol. 2011, 2, 499–500, doi:10.3762/bjnano.2.53
- nanophotonics, nano-optics and nanospectroscopy, and covers the field where nanoscience meets photonics, optics and spectroscopy. Since the pioneering days of scanning near-field optical microscopy [1][2], one of the main goals has been to combine scanning probe microscopy techniques with the spectroscopic
Plasmonic nanostructures fabricated using nanosphere-lithography, soft-lithography and plasma etching
Beilstein J. Nanotechnol. 2011, 2, 448–458, doi:10.3762/bjnano.2.49
- can be utilized in experiments requiring light confinement. Keywords: nanosphere-lithography; near-field enhancement; plasma etching; soft-lithography; surface plasmons; Introduction Classical electromagnetic theories describing optical transmission through small apertures [1][2] do not take into
- effects, such as optical resonances [5][6][7][8][9][10], near-field enhancements [11][12][13][14], enhanced scattering [15], enhanced transmission [3][4][16][17][18][19][20][21][22][23][24], and plasmonic whispering gallery modes [25][26][27]. Some of these effects have been explored in applications such
- structures with sharp edges, coated by gold films are suitable to confine light. The confinement efficiency and the plasmonic mode dispersion, leading to the highest near-field enhancements, need to be investigated in more depth. Conclusion Two novel methods of fabrication of plasmonic structures were
Scanning probe microscopy and related methods
Beilstein J. Nanotechnol. 2010, 1, 155–157, doi:10.3762/bjnano.1.18
- Microscopy, FMM: Force Modulation Microscopy, ic-AFM: intermittent contact AFM, TMAFM: tapping mode AFM, nc-AFM: non-contact AFM, KPFM: Kelvin probe force microscopy, EFM: Electrostatic force microscopy, MFM: Magnetic force microscopy, MRFM: Magnetic resonance force microscopy, NSOM: Near-field scanning
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