Compound-Specific δ^(34)S Analysis of Volatile Organics by Coupled GC/Multicollector-ICPMS

We have developed a highly sensitive and robust method for the analysis of δ^(34)S in individual organic compounds by coupled gas chromatography (GC) and multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The system requires minimal alteration of commercial hardware and is amenable to virtually all sample introduction methods. Isobaric interference from O_2^+ is minimized by employing dry plasma conditions and is cleanly resolved at all masses using medium resolution on the Thermo Neptune MC-ICPMS. Correction for mass bias is accomplished using standard−sample bracketing with peaks of SF6 reference gas. The precision of measured δ^(34)S values approaches 0.1‰ for analytes containing >40 pmol S and is better than 0.5‰ for those containing as little as 6 pmol S. This is within a factor of 2 of theoretical shot-noise limits. External accuracy is better than 0.3‰. Integrating only the center of chromatographic peaks, rather than the entire peak, offers significant gain in precision and chromatographic resolution with minimal effect on accuracy but requires further study for verification as a routine method. Coelution of organic compounds that do not contain S can cause degraded analytical precision. Analyses of crude oil samples show wide variability in δ^(34)S and demonstrate the robustness and precision of the method in complex environmental samples

Modelling of figure-eight all-fiber laser

The figure-eight fiber laser is considered in two configurations, with either a unidirectional active ring cavity coupled with a nonlinear optical loop mirror (NOLM) or a unidirectional passive cavity and a nonlinear amplifying loop mirror (NALM). In each case, we derive a master equation of cubic complex Ginzburg Landau (CGL) type, in which the coefficients explicitly depend on the characteristics of the cavity. Single-pulse and continuous wave (cw) solutions in both normal and anomalous dispersion are discussed analytically

Pluie de solitons dans un laser à fibre co-dopée Er:Yb en forme de huit

Nous rapportons ici l\u27observation expérimentale d\u27un comportement collectif d\u27un ensemble de soliton, appelé pluie de solitons, dans un laser à fibre en forme de huit avec un miroir à boucle non linéaire (NOLM). Cette dynamique non linéaire a été précédemment observée dans un laser à fibre verrouillé passivement par la technique de rotation de polarisation non linéaire. A partir d\u27un fond continu, des solitons se créent et dérivent vers la phase condensée de plusieurs solitons. L\u27observation de cette dynamique tend à renforcer l\u27idée de l\u27universalité du comportement collectif des solitons. 

Auto-organisation d’un grand nombre d’impulsions dans un laser à fibre dope Er:Yb

Nous proposons une étude inédite de l’interaction d’un grand nombre d’impulsions dans un laser à fibre double gaine dopée à l\u27Er :Yb fonctionnant par rotation non linéaire de la polarisation. A cause des phénomènes d\u27attractions et de répulsions entre solitons, des régimes auto-organisés peuvent être générés. Par analogie avec les états de la matière, nous nous sommes intéressés aux régimes "gaz de solitons", "jet supersonique de solitons", "polycristal de solitons", "liquide de solitons" et "cristal de solitons"

Comparative study of soliton complexes in different laser configurations

We investigate the formation of self-organized and disorganized soliton structures in passively mode-locked Er:Yb doped double-clad fiber laser. Two laser configurations are studied. The first one is based on mode-locking through nonlinear polarization rotation while the second geometry is a figure-eight cavity in which the mode-locking is obtained with a nonlinear optical loop mirror. Although the physical mechanisms of mode-locking are different, we demonstrate that collective behaviours and soliton complexes are similar in both configurations. That demonstrates the universality of the solitonic structures

Soliton pattern formation in figure-of-eight laser

We investigate the soliton pattern formation in an erbium-doped figure-of-eight double-clad fiber laser. The mode-locking is realized with a nonlinear amplifying loop mirror. Different soliton complexes have been obtained similar to those obtained when the mode-locking is achieved through the nonlinear polarization rotation technique

Intricate solitons state in passively mode-locked fiber lasers

We report a novel spontaneous soliton pattern formation in a figure-of-eight passively mode-locked erbium-doped double-clad fiber laser. It consists in a condensate phase in which there is almost periodic arrangement of alternate crystal and liquid soliton phases. Thanks to an adapted ansatz for the electric field, we perform a reconstruction allowing to clearly identify the soliton distribution along the cavity

Laser à fibre verrouillé en phase à haute cadence

We investigate different ways to considerably increase the repetition-rate of passively mode-locked fiber lasers. We first report the harmonic mode-locking of a double-clad fiber laser passively mode-locked through nonlinear polarization rotation. We then consider the theoretical possibility to generate a bound-state filling the optical cavity thus resulting in ultra-high repetition rate with a remarkable stability

Dissipative Soliton Resonance in Passive Mode-Locked Lasers

By numerical simulation it is found that the dissipative soliton resonance prevents to an appearance in generation of new pulses with increasing pump power. It can be used for generation of high-energy pulses