Search results for "Mixing"
showing 10 items of 795 documents
Multispectrum fits for line mixing in the ν3 band Q branch of methane
2003
International audience; First-order line-mixing coefficients and model relaxation matrix element scaling factors have been obtained for allowed transitions in the nu3 band Q branch of CH4 broadened by H2, He, N2, O2, Ar, and CH4. The broadening, shifting, Dicke-narrowing, and line-mixing parameters are determined by simultaneous least-squares fitting of spectra at pressures from 0.014 to 66.66 kPa recorded with a high-resolution difference-frequency laser. These results confirm, improve, and extend a previous analysis of the lower pressure (613.3 kPa) data [A.S. Pine, J. Chem. Phys. 97 (1992) 773] which yielded averaged coefficients of individually fit spectra where adjacent broadened lines…
Statistics of transitions for Markov chains with periodic forcing
2013
The influence of a time-periodic forcing on stochastic processes can essentially be emphasized in the large time behaviour of their paths. The statistics of transition in a simple Markov chain model permits to quantify this influence. In particular the first Floquet multiplier of the associated generating function can be explicitly computed and related to the equilibrium probability measure of an associated process in higher dimension. An application to the stochastic resonance is presented.
Titan's 3-micron spectral region from ISO high-resolution spectroscopy
2006
Abstract The near-infrared spectrum of Titan, Saturn's largest moon and one of the Cassini/Huygens' space mission primary targets, covers the 0.8 to 5 micron region in which it shows several weak CH 4 absorption regions, and in particular one centered near 2.75 micron. Due to the interference of telluric absorption, only part of this window region (2.9–3.1 μm) has previously been observed from the ground [Noll, K.S., Geballe, T.R., Knacke, R., Pendleton, F., Yvonne, J., 1996. Icarus 124, 625–631; Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., 1998. Nature 395, 575–578; Griffith, C.A., Owen, T., Geballe, T.R., Rayner, J., Rannou, P., 2003. Science 300, 628–630; Geballe, T.R., Kim, S.J.…
Suppression of plasma contribution in femtosecond degenerate four-wave mixing (fs-DFWM) at high intensity
2007
Femtosecond degenerate four-wave mixing (fs-DFWM) experiments in CO2 exhibit a strong background due to plasma produced at high intensity (≥20 TW/cm2), when significant molecular alignment is likely to arise. This perturbing phenomenon renders the measurements of alignment very difficult. It is shown that the plasma contribution can be avoided by employing perpendicular polarizations for the two pump pulses. The effect is explained on the basis of the different diffraction angles between signals produced by molecular alignment and plasma. Copyright © 2007 John Wiley & Sons, Ltd.
Generation of a 160-GHz transform-limited pedestal-free pulse train through multiwave mixing compression of a dual-frequency beat signal.
2002
International audience; We report the experimental generation of a 160-GHz picosecond pulse train at 1550 nm, using multiple four-wave mixing temporal compression of an initial dual-frequency beat signal in the anomalous-dispersion regime of a nonzero dispersion-shifted fiber. Complete intensity and phase characterizations of the pulse train were carried out by means of a frequency-resolved optical gating technique, showing that 1.27-ps transform-limited pedestal-free Gaussian pulses were generated.
Tunable source of infrared pulses in gas-filled hollow core capillary
2020
International audience; We report a tunable source that generates pulses in the infrared from an optical parametric amplification in a gas-filled hollow core capillary based on four-wave mixing process, in which the phase matching strongly depends on the gas pressure and the pump. In our case, we have generated pulses from 1 to 1.6 m in the sub-µJ level together with a parametric amplification in the visible.
Cascaded intermodal four-wave mixing in a few-mode fiber
2019
During the last few years, intensive works on multimode fibers allowed for the observation of a series of complex and novel nonlinear spatiotemporal phenomena such as: multimode solitons, geometric parametric instability, supercontinuum generation, and self-induced beam cleaning [1-4]. Among these phenomena, intermodal four-wave mixing (IMFWM) demonstrated larger frequency shifts in comparison with single-mode fibers. In this work, we studied IMFWM in a few-mode graded-index fiber (GRIN-FMF) pumped in the normal dispersion regime at 1064 nm. We report parametric sidebands detuned by hundreds of THz from the pump.
Gain sideband splitting in dispersion oscillating fibers
2014
International audience; We analyze the modulation instability spectrum in a varying dispersion optical fiber as a function of the dispersion oscillation amplitude, and predict a novel sideband splitting into different sub-sidebands for relatively large dispersion oscillations
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…
Four-wave mixing process induced by a self-phase modulated pulse in a hollow core capillary
2021
International audience; <span class="markedContent" id="page11R_mcid8"><span style="left: 247.583px; top: 366.24px; font-size: 16.6667px; font-family: sans-serif;" role="presentation" dir="ltr"></span><span style="left: 253px; top: 366.24px; font-size: 16.6667px; font-family: sans-serif; transform: scaleX(0.941702);" role="presentation" dir="ltr">In this work, we investigate the modal </span><span style="left: 518.183px; top: 366.24px; font-size: 16.6667px; font-family: sans-serif;" role="presentation" dir="ltr"> </span><span style="left: 519.8px; top: 366.24px; font-size: 16.6667px; font-family: sans-serif; transform: scaleX(0.958087);" role="presentation" dir="ltr">four wa…