110 research outputs found
Interplay of Kerr and Raman beam cleaning with a multimode microstructure fiber
We experimentally study the competition between Kerr beam self-cleaning and
Raman beam cleanup in a multimode air-silica microstructure optical fiber. Kerr
beam self-cleaning of the pump is observed for a certain range of input powers
only. Raman Stokes beam generation and cleanup lead to both depletion and
degradation of beam quality for the pump. The interplay of modal four-wave
mixing and Raman scattering in the infrared domain lead to the generation of a
multimode supercontinuum ranging from 500 nm up to 1800 nm
Self-cleaning on a higher order mode in ytterbium-doped multimode fiber with parabolic profile
We experimentally demonstrate polarization-dependent Kerr spatial beam self-cleaning into the LP11 mode of an Ytterbium-doped multimode optical fiber with parabolic gain and refractive index profiles
Spatiotemporal Characterization of Supercontinuum Extending from the Visible to the Mid-Infrared in Multimode Graded-Index Optical Fiber
We experimentally demonstrate that pumping a graded-index multimode fiber
with sub-ns pulses from a microchip Nd:YAG laser leads to spectrally flat
supercontinuum generation with a uniform bell-shaped spatial beam profile
extending from the visible to the mid-infrared at 2500\,nm. We study the
development of the supercontinuum along the multimode fiber by the cut-back
method, which permits us to analyze the competition between the Kerr-induced
geometric parametric instability and stimulated Raman scattering. We also
performed a spectrally resolved temporal analysis of the supercontinuum
emission.Comment: 5 pages 7 figure
Genes encoding multiple forms of phospholipase A(2) are expressed in immature forms of human leukemic blasts.
International audiencenon
Spatial beam self-cleaning and supercontinuum generation with Yb-doped multimode graded-index fiber taper based on accelerating self-imaging and dissipative landscape
We experimentally demonstrate spatial beam self-cleaning and supercontinuum generation in a tapered Ytterbium-doped multimode optical fiber with parabolic core refractive index profile when 1064 nm pulsed beams propagate from wider (122 µm) into smaller (37 µm) diameter. In the passive mode, increasing the input beam peak power above 20 kW leads to a bell-shaped output beam profile. In the active configuration, gain from the pump laser diode permits to combine beam self-cleaning with supercontinuum generation between 520-2600 nm. By taper cut-back, we observed that the dissipative landscape, i.e., a non-monotonic variation of the average beam power along the MMF, leads to modal transitions of self-cleaned beams along the taper length
Frequency-Resolved Spatial Beam Mapping in Multimode Fibers: Application to Mid-Infrared Supercontinuum Generation
We present a new spatial-spectral mapping technique permitting to measure the
beam intensity at the output of a graded-index (GRIN) multimode fiber with
sub-nanometric spectral resolution. We apply this method to visualize the fine
structure of the beam shape of a sideband generated at 1870 nm by geometric
parametric instability (GPI) in a GRIN fiber. After spatial-spectral
characterization, we amplify the GPI sideband with a Tm-doped fiber amplifier
to obtain a microjoule-scale picosecond pump whose spectrum is finally
broadened in a segment of InF3 optical fiber to achieve supercontinuum ranging
from 1.7 {\mu}m up to 3.4 {\mu}mComment: 4 pages, 6 Figure
Spatiotemporal Nonlinear Interactions in Multimode Fibers
We observe experimentally a novel spatiotemporal dynamics of multimode fibers allowing for a new type of parametric instability and an original phenomenon of light self-organisation. Our experiments agree well with theoretical predictions and numerical simulations based on the Gross-Pitaevskii equation
- …