Active Galactic Nuclei at the Crossroads of Astrophysics

Over the last five decades, AGN studies have produced a number of spectacular examples of synergies and multifaceted approaches in astrophysics. The field of AGN research now spans the entire spectral range and covers more than twelve orders of magnitude in the spatial and temporal domains. The next generation of astrophysical facilities will open up new possibilities for AGN studies, especially in the areas of high-resolution and high-fidelity imaging and spectroscopy of nuclear regions in the X-ray, optical, and radio bands. These studies will address in detail a number of critical issues in AGN research such as processes in the immediate vicinity of supermassive black holes, physical conditions of broad-line and narrow-line regions, formation and evolution of accretion disks and relativistic outflows, and the connection between nuclear activity and galaxy evolution.Comment: 16 pages, 5 figures; review contribution; "Exploring the Cosmic Frontier: Astrophysical Instruments for the 21st Century", ESO Astrophysical Symposia Serie

Soliton spectral tunnelling in photonic crystal fibre with sub-wavelength core defect

International audienceA numerical study of soliton spectral tunnelling in an index-guiding photonic crystal fibre with a sub-wavelength central air core defect is presented. Specifically, for a fibre design where two regions of anomalous dispersion bracket a 90 nm wide region of normal dispersion, simulations show tunnelling from 1300 to 1475 nm across the forbidden normal dispersion regime, with near unity efficiency. In addition, this effect can be exploited to obtain over a factor of two nonlinear pulse compression by interrupting propagation at the distance at which soliton tunnelling occurs

Génération de nanoparticules de niobate de lithium par ablation laser femtoseconde

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Studies and realization of an experimental set-up for micro Airy beams generation

International audienceIn this work, we propose a step up that combines a long focal lens L with a microscope objective lens (MO). A phase SLM positioned in the focal plane of the lens is illuminated by the Gaussian femtosecond beam. The modulation depth of the SLM introduces a bias that has to be filtered. Thus, we add to the cubic phase term a linear phase modulation directly onto the SLM

High aspect ratio nanochannel fabrication using non-diffracting femtosecond Bessel beams

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Optimized one-step compression of femtosecond fibre laser pulses to 30 fs in dispersion-flattened highly nonlinear fibre

International audienceIn this paper, however, we show that it is possible to obtain high quality nonlinear compressed pulses using only one segment of readily-available highly nonlinear fiber (HNLF). By directly splicing a very short (7 cm) length of HNLF to the output single mode fiber pigtail of a commercial femtosecond fiber laser, frequency resolved optical gating (FROG) confirms that nonlinear compression results in the generation of 28 fs pulses. This represents an extremely simple modification allowing an essentially loss-free factor-of-three reduction in pulse duration relative to the primary source

Morphological study of femtosecond laser nano-structured fused silica using atomic force microscopy

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Femtosecond micromachining of fused silica and applications to fiber optics

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