Search results for "electronics"
showing 10 items of 4340 documents
Near-field characterization of Bragg mirrors engraved in surface plasmon waveguides
2004
International audience; Surface plasmon waveguides (SPW's) are metal ridges featuring widths in the micrometer range and thicknesses of a few tens of nanometers. A focused ion beam has been used to carve microscatterers into gold SPW's and the near-field distributions around these microstructures are observed by means of photon scanning tunneling microscopy (PSTM). On the basis of near-field images, we show that a finite length periodic arrangement of narrow slits can reflect a surface plasmon mode propagating along a SPW. The reflection efficiency of the micrograting is found to depend upon the number of slits, the period of the grating, and the incident wavelength. The optimum reflection …
Influence of Fano resonance on SERS enhancement in Fano-plasmonic oligomers
2019
Plasmonic oligomers can provide profound Fano resonance in their scattering responses. The sub-radiant mode of Fano resonance can result in significant near-field enhancement due to its light trapping capability into the so-called hotspots. Appearance of these highly localized hotspots at the excitation and/or Stokes wavelengths of the analytes makes such oligomers promising SERS active substrates. In this work, we numerically and experimentally investigate optical properties of two disk-type gold oligomers, which have different strength and origin of Fano resonance. Raman analysis of rhodamine 6G and adenine with the presence of the fabricated oligomers clearly indicates that an increment …
Simulation of surface-modified porous silicon photonic crystals for biosensing applications
2012
In this work realistic biosensing structures based on the integration of porous silicon photonic crystals with polymer coating technology are presented. Microcavities and rugate filters are chosen as the photonic crystal configuration. The deposition of a polymer layer on the pore walls of these structures is proposed to improve the selectivity and sensitivity of the sensing function. A complete effective refractive index model including the polymer layer, the target and external effects like silicon oxidation has been developed in order to accurately simulate the structures. It is expected that the proposed structures could be used as low cost, highly integrated and highly sensitive biolog…
Thermo-optic control of dielectric-loaded plasmonic Mach-Zehnder interferometers and directional coupler switches
2012
We report detailed experimental studies of compact fiber-coupled dielectric-loaded plasmonic waveguide components-Mach-Zehnder interferometers (MZIs) and directional couplers (DCs)-whose operation at telecom wavelengths is controlled via the thermo-optic effect by electrically heating the gold stripe of dielectric-loaded plasmonic waveguides. The effect of the gaps isolating the heated part of the waveguide from the rest of the structure was examined showing the presence of a Fabry-Perot cavity in this MZI arm. Wavelength-dependent modulation is demonstrated with MZI-based components, and wavelength dependent low power (similar to 0.92 mW) rerouting is achieved with DC switches. Furthermore…
Theory of parabolic pulse propagation in nonlinear dispersion decreasing optical fiber amplifiers
2008
Optical fibers ; Nonlinear optics ; Optical fiber amplifiers ; Optical amplifier ; Optical solitons ; Electromagnetic wave propagation ; Pulse propagation ;; International audience; We show that pulse spectral broadening in normally dispersive nonlinear fiber amplifiers may be enhanced by introducing a suitable dispersion tapering. We obtain an analytical dispersion profile that permits one to reduce pulse propagation in a varying dispersion fiber to the case of an equivalent fiber with constant parameters.
Near-field coupling of a point-like dipolar source with a thin metallic film: Implication for STM plasmon excitations
2012
International audience; Recent experiments have shown that it is possible to excite surface plasmons on metallic films by injecting tunnel electrons from a sharp metal tip located in the immediate proximity of the sample. When working close to a bare metal film, the excitation of surface plasmons gives rise to typical circular patterns that can be recorded in both image and Fourier planes. Important physical parameters of surface plasmon propagation such as their propagation length can be extracted from these images. In this Letter, we discuss theoretically the physics of the plasmonic excitations induced by a STM tip.
High frequency microwave signal generation using dual-wavelength emission of cascaded DFB fiber lasers with wavelength spacing tunability
2010
[EN] A dual wavelength fiber laser source based on two cascaded phase-shifted fiber Bragg gratings is presented The gratings are written in an erbium-doped fiber each configuring the cavity of a distributed feedback fiber laser The spacing between lasing modes is controlled dynamically by the use of piezoelectric actuators A continuous tuning range of 5-724 pm of the wavelength difference which is equivalent to a photodetected 072-92 GHz range is obtained Efficient generation from the L to the W microwave and millimeter bands has been achieved by heterodyne photodetection of the dual-wavelength optical signal (C) 2010 Elsevier BV All rights reserved
Stiffer, Stronger and Centrosymmetrical Class of Pentamodal Mechanical Metamaterials
2019
Pentamode metamaterials have been used as a crucial element to achieve elastical unfeelability cloaking devices. They are seen as potentially fragile and not simple for integration in anisotropic structures due to a non-centrosymmetric crystalline structure. Here, we introduce a new class of pentamode metamaterial with centrosymmetry, which shows better performances regarding stiffness, toughness, stability and size dependence. The phonon band structure is calculated based on the finite element method, and the pentamodal properties are evaluated by analyzing the single band gap and the ratio of bulk and shear modulus. The Poisson&rsquo
Design, near-field characterization, and modeling of 45 circle surface-plasmon Bragg mirrors
2006
The development of surface plasmon polariton (SPP) optical elements is mandatory in order to achieve surface plasmon based photonics. A current approach to reach this goal is to take advantage of the interaction of SPP with defects and design elements obtained by the micro- or nano-structuration of the metal film. In this work, we have performed a detailed study of the performance and behavior of SPP-Bragg mirrors, designed for 45\ifmmode^\circ\else\textdegree\fi{} incidence, based on this approach. Mirrors consisting of gratings of both metal ridges on the metal surface and grooves engraved in the metal, fabricated by means of electron beam lithography and focused ion beam, have been consi…
Frequency tunable polarization and intermodal modulation instability in high birefringence holey fiber
2009
International audience; We present an experimental analysis of polarization and intermodal noise-seeded parametric amplification, in which dispersion is phase matched by group velocity mismatch between either polarization or spatial modes in birefringent holey fiber with elliptical core composed of a triple defect. By injecting quasi-CW intense linearly polarized pump pulses either parallel or at 45 degrees with respect to the fiber polarization axes, we observed the simultaneous generation of polarization or intermodal modulation instability sidebands. Furthermore, by shifting the pump wavelength from 532 to 625 nm, we observed a shift of polarization sidebands from 3 to 8 THz, whereas int…