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International audience; We report on a nonlinear compression down to 20 fs in air-filled HCPCF. Novel spectraltemporal dynamic is demonstrated. Spectral bouncing of the compressed pulse is triggered by the interplay between Raman redshift and plasma blueshift.

International audience; We report on the use and qualification of the recently developed single-mode hybrid hollow-core photonic crystal fiber for a robust and long-life acetylene photonic micro-cell based optical frequency reference.

Gas-filled Hollow Core Photonic Cristal Fibres (HCPCF) or Photonic MicroCell (PMC) [1] has proven to offer an outstanding gas-cell for laser metrology and spectroscopy applications. Sub-Doppler spectral features, generated via electromagnetically induced transparency (EIT) or saturated absorption (SA), have been generated in molecular gases despite the weak strength of their optical transitions [1–4], and an optical frequency reference with excellent accuracy has been demonstrated [1]. So far, the reported stand-alone PMCs are either made by hermetically splicing the HCPCF tips to an all-solid optical fibre [1,2] or by encapsulating them to a glass cell [3]. All these techniques show limitations. For example, the splicing based all-fibre PMC technique is not adapted to all fibres as it requires matching the outer-diameter and/or mode-field-diameters of the two fibres. Also the use of fibre tapering to reduce this mismatch [2] remains too cumbersome for the obtained splice-loss figures, which are >2 dB and exhibit asymmetric loss. Furthermore, the use of Helium (He) gas during the "air-ambient" splicing process to avoid air pollution in the fibre core renders this technique too sensitive to residual gas contamination. Conversely, the technique of encapsulating the fibre tip in an enlarged borosilicate capillary [3] presents potential contamination during and after fabrication because of the use of Epoxy glue, and the ensued outgassing, which is detrimental for optimized observation of sub-Doppler features and for the life time of the PMC.

International audience; In this letter, we report on the fabrication of an inhibited-coupling guiding fiber with a cladding amorphous lattice of nine tubes exhibiting a record loss of 13.8 dB/km at 539 nm. The fiber has been drawn over a length of 1 km with high stability during the drawing process (outer diameter variation of ±0.2%). To our knowledge, this is the first time that loss figures and the fundamental Rayleigh scattering limit of silica are reported for a hollow-core optical fiber in the green spectral range. Also, this is the first report on a tubular fiber draw over such a long length. Additionally, this record loss figure is the lowest ever demonstrated with any kind of optical fibers in the green spectral range.

Hollow-core photonic crystal fibre (HCPCF) proved to be a powerful platform for optical pulse compression. Several results, reported in the last few years, show both exceptional compression performances over a large energy dynamic range and varied experimental conditions [1][2][3], and new physical dynamics [4]. Among the reported performances, we list those achieved with Inhibited-Coupling guiding HCPCF (IC-HCPCF), and where soliton self-compression down to the single or a few cycle regime were achieved with a ∼1.8 μm wavelength and 80 fs duration input-pulse [1], and with a 790 nm wavelength and 24 fs duration input-pulse [2]. Conversely, the low values and spectral profile of the IC-HCPCF dispersion, combined with its fine control through a judicious choice of a filling gas, enabled the observation of several nonlinear optical regimes as varied as modulation instability, self-phase modulation, supercontinuum generation, or plasma-induced soliton blue-shift and fission. Remarkably, in the latter regime, experimental and theoretical results show that soliton-plasma interaction and its high sensitivity to the input laser and IC-HCPCF parameters are overarching several novel solitonic phenomena[4]-[6] such as strong soliton self-compression, blue and red frequency-shift and fission.

International audience; We report on a user-friendly sub-100 fs nonlinear pulse compression platform named FastLas. The compressor is based on gas fillable inhibited-coupling fibers and can be scaled over a large parameter-space of the input pulse. OCIS codes: 320.5520, 320.7140, 060.5295 1. Introduction Over the last two decades, ultra-short pulse (USP) lasers have witnessed a dramatic progress in their design, performance and in their applications. Nowadays, commercially available table-top lasers emitting pulses with duration of hundreds of femtosecond and milli-Joule energy have become a common place. Among the most representative of these USP lasers, we count Ti:Sapph laser emitting at around 800 nm for, Yb-based laser emitting around 1 µm, and Er-based laser emitting around 1.5 µm, and their frequency-doubled and tripled versions. Within this landscape, the laser pulse-duration is often larger than 100 fs, and achieving sub-100 fs pulse duration still remains a challenge. Among the limiting factors in pulse compression is the narrow gain-bandwidth of some lasers (e.g. Yb-based and Er-based lasers), which requires further spectral-broadening followed with a post-compression, and/or nonlinear compression. Furthermore, even with larger gain bandwidth lasers such as Ti:Sapph, complex setup are required for efficient dispersion compensation. Finally, the high sensitivity of current pulse-compression schemes to well defined parameter set of the input laser such as pulse energy, pulse duration, and wavelength, makes it extremely challenging to have efficient and scalable USP compressors. This situation is illustrated by state-of-the-art of Yb-based lasers. The latter offers a superior power-scaling, it can be operated in different operational modes, such as emitting from CW regime to 100 fs pulses with repetition rate from kHz to GHz repetition rate. Achieving sub-100 fs remains a challenging task despite the implementation of ingenious schemes to overpass this limitation [1]. In turn, this limits their impact in some of the emerging industrial applications where processing of some materials such as dielectric or semiconductor require 10-100 µJ level pulses with pulse-width below 300 fs. Here, we exploit the engineerable dispersion, the broadband transmission and high energy handling of Inhibted-Coupling guiding hollow-core photonic crystal fiber (IC-HCPCF) to propose a USP compression platform coined FastLas, which operates on energy range between few microjoules to hundred microjoules and efficient for a wide variety of wavelengths.

The dramatic progress in power-scaling of ultra-short pulse (USP) lasers and their continuous expansion use in industrial applications call for flexible and robust beam delivery systems (BDS) over several meters. Recently, a new branch of hollow-core photonic crystal fiber (HC-PCF) based on inhibited coupling (IC) mechanism has been proposed and successfully applied to demonstrate the delivery of milliJoule 600 femtosecond pulses in a several meter long piece and in robustly single-mode fashion [1]. Despite this breakthrough, it is desirable to reduce further the attenuation and enlarge the operating bandwidth of such fiber to increase the capability of the BDS whilst keeping the same delivery performances. In this context, a carefully optimization of the geometrical parameters of the core contour (i.e., the curvature b [2] and the silica thickness t) is studied resulting in the fabrication of new state-of-the-art IC Kagome HC-PCF combining losses less than 10 dB/km for the first time and associated to an enlarged transmission bandwidth able to cover all the entire industrial spectral range.

Le mode de détention des biens professionnels est une problématique actuelle pour les chefs d’entreprises français. La holding apparaît comme un outil intéressant sur le plan fiscal, juridique, comptable et patrimonial. Le thème des holdings étant très vaste, ce mémoire n’a pas vocation à aborder toutes les notions les concernant. Nous verrons en quoi une société holding peut être considérée comme un outil de transition efficace pour passer d’un patrimoine professionnel à un patrimoine privé. Ce travail pourra alors servir de conseil à des chefs d’entreprises s’interrogeant sur les avantages que présente la holding dans le rachat et l’exploitation d’une société cible ainsi que sur l’impact que pourrait avoir une cession ou une transmission de cette même société. Les aspects abordés correspondront donc à deux phases importantes de la vie du chef d’entreprise, à savoir la naissance de son projet professionnel et l’optimisation de son départ en retraite.