Search results for " Emission"
showing 10 items of 1496 documents
Experimental demonstration of 160-GHz densely dispersion-managed soliton transmission in a single channel over 896 km of commercial fibers
2003
International audience; We experimentally demonstrate the first 160-GHz densely dispersion-managed soliton transmission in a single channel at 1550 nm over nearly 900 km using commercially available non-zero dispersion-shifted fibers. This performance has been achieved by using a 16 km-long recirculating loop configuration and an appropriate design of the dispersion map.
Flaticon pulses in optical fibers
2014
International audience; We experimentally investigate the nonlinear reshaping of a continuous wave which leads to chirp-free and flat-top intense pulses or flaticons exhibiting strong temporal oscillations at their edges and a stable self-similar expansion upon propagation of their central region.
Far-field imaging of the electromagnetic local density of optical states.
2008
International audience; We introduce a new experimental method to measure the local electromagnetic density of states (LDOS) by integrating the differential scattering cross section. The signal detected essentially reflects the intrinsic scattering response of the photonic structures and renders the partial LDOS dominated by evanescent modes. We give a theoretical understanding of the LDOS image formation and show a qualitative agreement between experimental images and theoretical maps. This approach can be practically applied to the direct measurement of an optical antenna's scattering efficiency and can provide valuable information for designing optimum structures utilized in radiative de…
Single-mode room-temperature emission with a silicon rod lattice
2006
The authors experimentally evidence an increase of light emission efficiency at room temperature in a silicon-on-insulator photonic crystal. The photonic crystal is made of a triangular lattice of silicon rods and operates as a single-mode light extractor. It exhibits a luminescence intensity two orders of magnitude higher than silicon-on-insulator substrate. In light of photoluminescence experiments, emission diagram measurements, and finite difference time domain calculations, they identify the different optical properties of the photonic crystal and they demonstrate the existence of at least a fivefold emission efficiency enhancement per surface unit.
New concepts based on nonlinear polarization effects and Raman amplification in optical fibers
2009
We report a theoretical analysis and experimental demonstration of a polarization attraction process at telecommunication wavelengths in isotropic optical fibers. The combined effects of polarization attraction and Raman amplification are also presented.
New developments in the study of optical parabolic pulses in normally dispersive fibers
2011
International audience; We report two recent studies dealing with the evolution of parabolic pulses in normally dispersive fibers. On the one hand, the nonlinear reshaping from a Gaussian intensity profile towards the asymptotic parabolic shape is experimentally investigated in a Raman amplifier. On the other hand, the significant impact of the fourth order dispersion on a passive propagation is theoretically discussed: we numerically demonstrate flat-top, coherent supercontinuum generation in an all-normal dispersion-flattened photonic crystal fiber. This shape is associated to a strong reshaping of the temporal profile what becomes triangular.
All optical solition-based 2R regeneration at 170 Gbps
2010
[NMB4]; International audience; We report the numerical and experimental studies of a spectrally filtered-based all-optical 2R regenerator at 170 Gbps. The fiber device is combined with a fast saturable absorber. BER assessment exhibits a receiver sensitivity improvement.
Differential Responses of Nitrate Reducer Community Size, Structure, and Activity to Tillage Systems
2009
ABSTRACT The main objective of this study was to determine how the size, structure, and activity of the nitrate reducer community were affected by adoption of a conservative tillage system as an alternative to conventional tillage. The experimental field, established in Madagascar in 1991, consists of plots subjected to conventional tillage or direct-seeding mulch-based cropping systems (DM), both amended with three different fertilization regimes. Comparisons of size, structure, and activity of the nitrate reducer community in samples collected from the top layer in 2005 and 2006 revealed that all characteristics of this functional community were affected by the tillage system, with increa…
Origin and diversity of testate amoebae shell composition: Example of Bullinularia indica living in Sphagnum capillifolium
2017
Testate amoebae are free-living shelled protists that build a wide range of shells with various sizes, shapes, and compositions. Recent studies showed that xenosomic testate amoebae shells could be indicators of atmospheric particulate matter (PM) deposition. However, no study has yet been conducted to assess the intra-specific mineral, organic, and biologic grain diversity of a single xenosomic species in a natural undisturbed environment. This study aims at providing new information about grain selection to develop the potential use of xenosomic testate amoebae shells as bioindicators of the multiple-origin mineral/organic diversity of their proximal environment. To fulfil these objective…
Left-Ventricle Segmentation of SPECT Images of Rats
2015
Single-photon emission computed tomography (SPECT) imaging of the heart is helpful to quantify the left-ventricular ejection fraction and study myocardial perfusion scans. However, these evaluations require a 3-D segmentation of the left-ventricular wall on each phase of the cardiac cycle. This paper presents a fast and interactive graph cut method for 3-D segmentation of the left ventricle (LV) of rats in SPECT images. The method is carried out in three steps. First, 3-D sampling of the LV cavity is made in a spherical-cylindrical coordinate system. Then, a graph-cut-based energy minimization procedure provides delineation of the myocardium centerline surface. From there, it is possible to…