Search results for "Mixing"
showing 10 items of 795 documents
Influence of parametric four-wave mixing effects on stimulated Raman scattering in bimodal optical fibers.
2007
We analyze stimulated Raman scattering in normally dispersive bimodal fibers under single-frequency pumping conditions. Experiments show that whenever the interacting nonlinear waves propagate in the LP(01) and LP(11) modes, a parametric four-wave mixing enters unavoidably into play in the wave-coupling behavior, which causes qualitatively different phenomena compared with the ordinary process of Raman scattering, such as the parametric suppression of the first-order Raman Stokes radiation.
Effects of refractive index changes on four-wave mixing bands in Er-doped photonic crystal fibers pumped at 976 nm.
2012
An experimental study of the effects of an auxiliary 976 nm pump signal on the four-wave mixing parametric bands generated with a 1064 nm pump in a normal dispersion Er-doped photonic crystal fiber is presented. The four-wave mixing signal and idler bands shift to shorter and longer wavelengths, respectively, with increasing 976 nm pump power. It is shown that the wavelength-dependent resonant refractive index change in the erbium-doped core under 976 nm pumping is at the origin of the effect.
Broadband tuning of polarization modulation instability in microstructured optical fibers
2020
The wideband tuning of strong bands generated through polarization modulation instability (PMI) in microstructured optical fibers (MOFs) is reported. Tunability is achieved by exploiting the dependence of the phase-matching condition on the fiber’s chromatic dispersion and birefringence, which is particularly sensitive when the fiber is pumped near the zero-dispersion wavelength. MOFs designed to accomplish PMI phase-matching when they are infiltrated with ethanol and pumped at 1064 nm were designed and fabricated. Taking advantage of the large thermo-optic coefficient of ethanol, both chromatic dispersion and birefringence were varied through temperature. Wavelength shifts from 937 nm to 8…
Multiple four-wave mixing in optical fibers: 1.5–3.4-THz femtosecond pulse sources and real-time monitoring of a 20-GHz picosecond source
2010
International audience; In this work, we report recent progress on the design of all-fibered ultra-high repetition-rate pulse sources for telecommunication applications around 1550 nm. The sources are based on the non-linear compression of an initial beat-signal through a multiple four-wave mixing process taking place into an optical fiber. We experimentally demonstrate real-time monitoring of a 20 GHz pulse source having an integrated phase noise 0.01 radian by phase locking the initial beat note against a reference RF oscillator. Based on this technique, we also experimentally demonstrate a well-separated high-quality 110 fs pulse source having a repetition rate of 2 THz. Finally, we show…
Global impact of monocyclic aromatics on tropospheric composition
2017
Abstract. Aromatic compounds are reactive species influencing ozone formation, OH concentrations and organic aerosol formation. An assessment of their impacts on the gas-phase composition at a global scale has been performed using a general circulation atmospheric-chemistry model. Globally, we found a small annual average net decrease (less than 3 %) in global OH, ozone, and NOx mixing ratios when aromatic compounds are included in the chemical mechanism. This inclusion of aromatics also results in CO mixing ratio increases, which cause a general decrease in OH concentrations. The largest changes are found in glyoxal and NO3, with increases in the atmospheric burden of 10 % and 6 %, respect…
A composite study on the structure and formation of ozone miniholes and minihighs over central Europe
2005
[1] Two different mechanisms have been proposed to be important for the formation of extreme total ozone events in mid-latitudes, so-called miniholes: (A) far-range meridional transport of air masses from regions with different climatological ozone mixing ratios, and (B) (local) adiabatic vertical displacement of isentropes. Here, the relative importance of these two mechanisms is studied using two different ozone profile reconstruction techniques for all miniholes and minihighs (events with anomalously high ozone) during the time period 1980–1989 over Switzerland. Composites for the two types of events of their vertical potential vorticity (PV) reveal a vertical dipole structure of PV anom…
Photo-stabilization of biopolymers-based nanocomposites with UV-modified layered silicates
2020
Abstract Eco-friendly in-situ stabilised biopolymer nanocomposites based on polyamide 11 (PA11) and polylactic acid (PLA) were prepared by melt mixing in the presence of a modified organo-montmorillonite clay containing a chemically-bound hindered amine UV-stabilising function, [(UV)OM-MMt]. Characterisation of the newly synthesised organo-modifier containing the reactive hindered amine (HAS) UV-stabilising function [(UV)OM] has confirmed a successful synthesis. The (UV)OM was then introduced into NaMMt through ion exchange reaction to prepare the UV stabiliser-bound organo-modified-MMt, [(UV)OM-MMt]. The in-situ stabilised PA11- and PLA- nanocomposites (PA11-(UV)OM-MMt and PLA-(UV)OM-MMt) …
Non-Unitarity of the lepton mixing matrix at the European spallation source
2022
If neutrinos get mass through the exchange of lepton mediators, as in seesaw schemes, the neutrino appearance probabilities in oscillation experiments are modified due to effective nonunitarity of the lepton mixing matrix. This also leads to new CP phases and an ambiguity in underpinning the ''conventional'' phase of the three-neutrino paradigm. We study the CP sensitivities of various setups based at the European spallation source neutrino super-beam (ESSnuSB) experiment in the presence of nonunitarity. We also examine its potential in constraining the associated new physics parameters. Moreover, we show how the combination of DUNE and ESSnuSB can help further improve the sensitivities on …
Fick Diffusion Coefficients in Ternary Liquid Systems from Equilibrium Molecular Dynamics Simulations
2012
An approach for computing Fick diffusivities directly from equilibrium molecular dynamics (MD) simulations is presented and demonstrated for a ternary chloroform–acetone–methanol liquid mixture. In our approach, Fick diffusivities are calculated from the Maxwell–Stefan (MS) diffusivities and the so-called matrix of thermodynamic factors. MS diffusivities describe the friction between different molecular species and can be directly computed from MD simulations. The thermodynamic factor describes the deviation from ideal mixing behavior and is difficult to extract from both experiments and simulations. Here, we show that the thermodynamic factor in ternary systems can be obtained from density…
Evidence of basaltic magma intrusions in a trachytic magma chamber at Pantelleria (Italy)
2012
In the last 50 ka basalts have erupted outside the margin of the young caldera on the island of Pantelleria. The inner portion of the caldera has instead been filled by trachyte lavas, pantellerite lavas and pumice fall deposits. This paper focuses on a low-volume benmoreite lava topping the trachyte lava pile in the middle of the young caldera. The mineral chemistry, including trace elements in clinopyroxene (LA-ICP-MS), suggests that benmoreite is a hybrid product resulting from mixing between a trachytic magma and a basaltic end member even more primitive than those erupted during the past 50 ka. The principal inference is that basaltic magmas intruded the trachytic magma chamber below t…