Search results for "Wave"
showing 10 items of 6009 documents
Nonlinear pulse deceleration using photorefractive four-wave mixing
2009
We investigate the possibilities of the backward four-wave coupling based on the nonlocal photorefractive response for the nonlinear deceleration of light pulses. The presence of an additional external variable parameter—the pump intensity ratio—allows to improve the output characteristics of the decelerated pulses compared to those typical of the two-wave coupling. In particular, large delay times of the output pulses can be achieved without their strong amplification. This positive distinctive feature of the pulse deceleration occurs far from threshold of the mirrorless optical oscillation.
Conditions for waveguide decoupling in square-lattice photonic crystals
2004
We study coupling and decoupling of parallel waveguides in two-dimensional square-lattice photonic crystals. We show that the waveguide coupling is prohibited at some wavelengths when there is an odd number of rows between the waveguides. In contrast, decoupling does not take place when there is even number of rows between the waveguides. Decoupling can be used to avoid cross talk between adjacent waveguides.
Quantum Non-Markovian Collision Models from Colored-Noise Baths
2019
A quantum collision model (CM), also known as repeated interactions model, can be built from the standard microscopic framework where a system S is coupled to a white-noise bosonic bath under the rotating wave approximation, which typically results in Markovian dynamics. Here, we discuss how to generalize the CM construction to the case of frequency-dependent system–bath coupling, which defines a class of colored-noise baths. This leads to an intrinsically non-Markovian CM, where each ancilla (bath subunit) collides repeatedly with S at different steps. We discuss the illustrative example of an atom in front of a mirror in the regime of non-negligible retardation times.
Coupling evanescently low loss Silicon-on-insulator ridge waveguides including high Q nanocavities for light control
2011
Summary form only given. In this work, we propose an innovative way to achieve an air-slotted nanocavities by coupling evanescently low loss Silicon-on-insulator (SOI) ridge waveguides(WGs) including high Q nanocavities exhibiting an ultrasmall modal volume V. We first show that coupling two WGs allows us to achieve a field confinement within the air slot as low as lambda/30 while preserving a high group index of the guided modes. Then we demonstrate that merging such coupled WGs with state-of-the-art high-Q/small V nanocavities is a robust way to achieve a single compact (1 µm × 3 µm) air-slotted resonator on substrate. Finally, we extend the concept to multiple air-slotted resonator syste…
Purcell-enhancement of the radiative PL decay in perylenediimides by coupling with silver nanoparticles into waveguide modes
2017
In this work, an interesting approach to enhance the coupling between excitons and plasmons is proposed by integrating highly luminescent perylenediimides (PDIs) and Ag metal nanoparticles (MNPs) in the core of a multilayer dielectric waveguide. The combination of the weak plasmonic coupling and the high scattering of MNPs gives rise to a significant improvement of the PDI photoluminescence and Purcell factor (PF) in forward-scattering geometry. Furthermore, when the PDI-MNP system is used as the core of a multilayer waveguide, a Purcell factor enhancement larger than 10 is observed, which is explained by an increase in the exciton-plasmon coupling under the light confinement in the wavegui…
Aluminum Plasmonics: Fabrication and Characterization of Broadly Tunable Plasmonic Surfaces for Plasmon Molecule Strong-Coupling and Fluorescence Enh…
2018
Our work based on previous studies [1, 2] confirms, that simple aluminum nanostructures can be utilized as effective plasmonic resonators over a broad range of frequencies and wavelengths. The nanostructured surfaces, fabricated by electron-beam lithography demonstrated relatively narrow-band resonances and are suitable for various plasmonic applications ranging from metal enhanced fluorescence to strong-coupling [1, 2, 3, 4, 5] experiments. We represent data for molecule-plasmon coupling near the strong coupling limit and demonstrate that these aluminum structures do act as fluorescence increasing substrates. In this work, we used two different types of dyes. We studied the narrow band j-a…
Portable microwave assisted extraction: An original concept for green analytical chemistry.
2013
International audience; This paper describes a portable microwave assisted extraction apparatus (PMAE) for extraction of bioac-tive compounds especially essential oils and aromas directly in a crop or in a forest. The developed procedure, based on the concept of green analytical chemistry, is appropriate to obtain direct in-field information about the level of essential oils in natural samples and to illustrate green chemical lesson and research. The efficiency of this experiment was validated for the extraction of essential oil of rosemary directly in a crop and allows obtaining a quantitative information on the content of essential oil, which was similar to that obtained by conventional m…
Plasmon polaritons of metallic nanowires for controlling submicron propagation of light
1999
Laboratoire de Physique, Optique Submicronique, Universite´de Bourgogne, BP 47870, F-21078 Dijon, France~Received 29 April 1999!We use the Green dyadic technique to study the propagation of a local excitation along metallic nanowiresof a subwavelength cross section. The metallic nanowires are elongated parallelepipeds deposited on a trans-parent substrate. A tightly focused plane wave illuminates one end of the nanowires. The localized surface-plasmon resonances of the nanowires propagate the local excitations over distances larger than the incidentwavelength. The properties of the electromagnetic eigenmodes of the nanowires are analyzed in terms of thelocal density of states. @S0163-1829~9…
<title>Quantum chemistry studies of the O K-edge x-ray absorption in WO<formula><inf><roman>3</roman></inf></f…
2008
In this work we present an interpretation of experimental O K-edge x-ray absorption near edge structure (XANES) in perovskite-type WO3 and AWO3 compounds (A = H and Na) using three different first principles approaches: (i) fullmultiple- scattering (FMS) formalism (the real-space FEFF code), (ii) hybrid density functional theory (DFT) method with partial incorporation of exact Hartree-Fock exchange using formalism of the linear combination of atomic orbitals (LCAO) as implemented in the CRYSTAL code; (iii) plane-wave DFT method using formalism of the projectoraugmented waves (PAW) as implemented in the VASP code.
Carrier Transport in GaAs Nanowires Using Surface Acoustic Waves
2012
ABSTRACTThe oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited electrons and holes in GaAs nanowires (NWs) transferred to a SAW beam line on a LiNbO3 crystal. We show that carriers generated in the NW by a focused light spot can be acoustically transported to a second location, where they recombine emitting short light pulses. The results presented here demonstrate the high-frequency manipulation of carriers in NWs without the use of electrical contacts, which opens new perspectives for applications in opto-electronic devices operating at GHz frequencies.