Search results for " and optics"
showing 10 items of 4468 documents
Bend- and splitting loss of dielectric-loaded surface plasmon-polariton waveguides.
2008
International audience; The design, fabrication, characterization, and modeling of basic building blocks of plasmonic circuitry based on dielectric- loaded surface polariton waveguides, such as bends, splitters, and Mach- Zehnder interferometers are presented. The plasmonic components are realized by depositing subwavelength dielectric ridges on a smooth gold film using mass-production- compatible UV-photolithography. The near-field characterization at telecommunication wavelengths shows the strong mode confinement and low radiation and bend losses. The performance of the devices is found in good agreement with results obtained by full vectorial three-dimensional finite element simulations.…
Caustic Interpretation of the Abruptly Autofocusing Vortex beams
2021
We propose an effective scheme to interpret the abruptly autofocusing vortex beam. In our scheme, a set of analytical formulae are deduced to well predict not only the global caustic, before and after the focal plane, but also the focusing properties of the abruptly autofocusing vortex beam, including the axial position as well as the diameter of focal ring. Our analytical results are in excellent agreement with both numerical simulation and experimental results. Besides, we apply our analytical technique to the fine manipulation of the focusing properties with a scaling factor. This set of methods would be beneficial to a broad range of applications such as particle trapping and micromachi…
Polarization control in spun and telecommunication optical fibers
2011
International audience; We consider the counterpropagating interaction of a signal and a pump beam in a spun fiber and in a randomly birefringent fiber, the latter being relevant to optical telecommunication systems. On the basis of a geometrical analysis of the Hamiltonian singularities of the system, we provide a complete understanding of the phenomenon of polarization attraction in these two systems, which allows to achieve a control of the polarization state of the signal beam by adjusting the polarization of the pump. In spun fibers, all polarization states of the signal beam are attracted toward a specific line of polarization states on the Poincaré sphere, whose characteristics are d…
Influence of third-order dispersion on the propagation of incoherent light in optical fibers
2010
International audience; We study the influence of third-order dispersion effects on the propagation of an incoherent nonlinear wave in an optical fiber system. The wave spectrum is shown to exhibit a highly asymmetric deformation characterized by a lateral spectral shoulder and the subsequent formation of an unexpected constant spectral pedestal. A kinetic approach to the problem reveals the existence of an invariant that explains in detail the essential properties of such asymmetric spectral evolution of the wave.
Supercontinuum spectral-domain ghost imaging
2018
International audience; Ghost imaging is a technique that generates high-resolution images by correlating the intensity of two light beams, neither of which independently contains useful information about the shape of the object. Ghost imaging has been demonstrated in both the spatial and temporal domains, using incoherent classical light sources or entangled photon pairs. Here we exploit the recent progress in ultrafast real-time measurement techniques to demonstrate ultrafast, scan-free, ghost imaging in the frequency domain using a continuous spectrum from an incoherent supercontinuum light source with random spectral fluctuations. We demonstrate the application of this technique to broa…
Field-free one-dimensional alignment of ethylene molecule
2006
International audience; We report an experimental study of non-adiabatic laser-induced molecular alignment of ethylene (C2H4) using a linearly polarized short laser pulse of moderate intensity. The information about the confinement of the C=C bond axis along the direction of the applied electric field is obtained by measuring the depolarization of a second short pulse of weak intensity interacting with the molecules after they have been exposed to the first pulse. The experimental data are compared with the numerical simulation of the Schr¨odinger equation written for the non-resonant interaction of an asymmetric top rigid rotor with a linearly polarized electric field. The field-free align…
Wave turbulence in integrable systems: nonlinear propagation of incoherent optical waves in single-mode fibers.
2011
International audience; We study theoretically, numerically and experimentally the nonlinear propagation of partially incoherent optical waves in single mode optical fibers. We revisit the traditional treatment of the wave turbulence theory to provide a statistical kinetic description of the integrable scalar NLS equation. In spite of the formal reversibility and of the integrability of the NLS equation, the weakly nonlinear dynamics reveals the existence of an irreversible evolution toward a statistically stationary state. The evolution of the power spectrum of the field is characterized by the rapid growth of spectral tails that exhibit damped oscillations, until the whole spectrum ultima…
Numerical Maps for Fiber Lasers Mode Locked with Nonlinear Polarization Evolution: Comparison with Semi-Analytical Models
2008
We have used a fully vectorial model based on two coupled nonlinear Schrodinger equations to study mode locking and pulse generation initiated and stabilized by nonlinear polarization evolution in a stretched pulse, double-clad, Yb-doped, fiber laser. The model takes explicitly into account gain saturation, finite amplification bandwidth, Kerr-induced self- and cross-phase modulations, group velocity dispersion, polarization control, and linear birefringence. Complete maps versus the orientation of intra-cavity wave-plates have been established. They comprise a large variety of pulse regimes that can be simply obtained by turning the intracavity wave-plate: stable single pulse per round tri…
Methane line parameters in HITRAN
2003
Abstract Two editions of the methane line parameters (line positions, intensities and broadening coefficients) available from HITRAN in 2000 and 2001 are described. In both versions, the spectral interval covered was the same (from 0.01 to 6184.5 cm −1 ), but the database increased from 48,033 transitions in 2000 to 211,465 lines in 2001 because weaker transitions of 12 CH 4 and new bands of 13 CH 4 and CH3D were included. The newer list became available in 2001 in the “Update” section of HITRAN. The sources of information are described, and the prospects for future improvements are discussed.
Field-free molecular alignment induced by elliptically polarized laser pulses: Noninvasive three-dimensional characterization
2007
International audience; An investigation of field-free molecular alignment produced by elliptically polarized laser pulses is reported. Experiments are conducted in CO2 at room temperature. A noninvasive all-optical technique, based on the cross defocusing of a probe pulse, is used to measure the alignment along two orthogonal directions which is sufficient to provide a three-dimensional characterization. The field-free molecular alignment produced by a laser of elliptical polarization is in good agreement in terms of amplitude and shape with theoretical predictions. It turns out to be almost equivalent to the superposition of the effects that one would obtain with two individual cross-pola…