Search results for " and optics"
showing 10 items of 4468 documents
Local structure studies of SrTi16O3and SrTi18O3
2014
In this work we report on the local structure of Ti in SrTi 16 O3 (STO16) and SrTi 18 O3 (STO18) investigated in the low temperature range (6‐300K) by extended x-ray absorption fine structure and x-ray absorption near edge structure (XANES) spectroscopy at Ti K-edge and by optical second harmonic generation (SHG). By comparing XANES of STO16 and STO18 we have identified the isotopic effect which produces at T < 100K a noticeable difference in the measured mean square relative displacements (MSRD) of Ti‐O1 bonds: while STO16 follow the expected Einstein-like behavior, for STO18 we have measured an increase of MSRD values with decreasing temperature. This is an indication of an increasing off…
Nonlinear virtues of multimode fibre
2015
The finding that multimode optical fibres support a rich and complex mix of spatial and temporal nonlinear phenomena could yield a plethora of promising applications.
Atomic transition probabilities for selected Yb II lines emitted from a ferroelectric plasma source
2010
The relative intensities of several hundred emission lines of Yb II between 200 nm and 900 nm were obtained with the use of ferroelectric plasma source. These relative intensities obtained for lines from 21 energy levels have been used to determine the line branching fractions, which have then been combined with accurate experimental radiative lifetime measurements to give absolute transition probabilities for 111 Yb II lines. The obtained values were compared with theoretical and experimental data taken from available literature.
Highly Efficient Holmium-Doped All-Fiber ∼2.07-μm Laser Pumped by Ytterbium-Doped Fiber Laser at ∼1.13 μm
2018
We report a 2.07-μm Holmium-doped all-fiber laser (HDFL) pumped by a 1.13-μm Ytterbium-doped fiber laser (YDFL). Home-made alumino–germano–silicate holmium-doped fiber (HDF) served here as an active medium, optimized in terms of chemical composition and co-dopants’ concentrations. Laser action at 2.07 μm was assessed in simple Fabry–Perot cavity, formed by a couple of home-made fiber Bragg gratings (FBGs), inscribed directly in the HDF; this allowed notable diminishing of intracavity loss of the 2.07-μm laser. HDF was in-core pumped by the 1.13-μm double-clad YDFL with a power of ∼12.5 W, in turn pumped in-clad by a laser diode (LD) operated at 0.97 μm with ∼24.5-W output. Using optimal len…
All polarization-maintaining passively modelocked ytterbium-doped fiber lasers, behavior under two different cavity configurations
2020
Fil: Cuadrado-Laborde, Christian. Universidad de Valencia. Departamento de Física Aplicada; España Fil: Cuadrado-Laborde, Christian. Consejo Nacional de Investigaciones Científicas. Instituto de Física Rosario; Argentina Fil: Cuadrado-Laborde, Christian. Pontificia Universidad Católica Argentina. Facultad de Química e Ingeniería del Rosario; Argentina Fil: Carrascosa, Antonio. Universidad de Valencia. Departamento de Física Aplicada; España Fil: Diez, Antonio. Universidad de Valencia. Departamento de Física Aplicada; España Fil: Cruz, J. L. Universidad de Valencia. Departamento de Física Aplicada; España Fil: Andrés, M. V. Universidad de Valencia. Departamento de Física Aplicada; España Abs…
Kerr self-cleaning of pulsed beam in an ytterbium doped multimode fiber
2017
International audience; We experimentally demonstrate that Kerr spatial self-cleaning of a pulsed beam can be obtained in an amplifying multimode optical fiber. An input peak power of 500 W only was sufficient to produce a quasi-single-mode emission from the double-clad ytterbium doped multimode fiber (YMMF) with non-parabolic refractive index profile. We compare the self-cleaning behavior observed in the same fiber with loss and with gain. Laser gain introduces new opportunities to achieve spatial self-cleaning of light in multimode fibers at a relatively low power threshold.
Application of WGM Resonances to the Measurement of the Temperature Increment of Ho and Ho-Yb Doped Optical Fibers Pumped at 1125 and 975 nm
2021
Optical fiber characterization using whispering gallery mode resonances of the fiber itself has been demonstrated to be a powerful technique. In this work, we exploit the thermal sensitivity of whispering gallery mode resonances to characterize the pump-induced temperature increment in holmium doped and holmium-ytterbium codoped optical fibers. The technique relies on the measurement of the resonances’ wavelength shift due to temperature variation as a function of the pump power. Holmium doped fibers were pumped to the second excited level 5I6 of the Ho3+ ion using a laser diode at 1125 nm and ytterbium-holmium codoped fibers to the 2F5/2 level of the Yb3+ ion by a laser diode at 975 nm. Ou…
Impact of buffer gas quenching on the $^1S_0$ $\to$ $^1P_1$ ground-state atomic transition in nobelium
2017
International audience; Using the sensitive Radiation Detected Resonance Ionization Spectroscopy (RADRIS) techniquean optical transition in neutral nobelium (No, Z = 102) was identified. A remnant signal when delaying the ionizing laser indicated the influence of a strong buffer gas induced de-excitation of the optically populated level. A subsequent investigation of the chemical homologue, ytterbium (Yb, Z = 70), enabled a detailed study of the atomic levels involved in this process, leading to the development of a rate equation model. This paves the way for characterizing resonance ionization spectroscopy (RIS) schemes used in the studyof nobelium and beyond, where atomic properties are c…
Luminescence properties of zirconia nanocrystals prepared by solar physical vapor deposition
2014
Abstract Zirconia nanocrystals have attracted considerable interest as biolabels, which can be used as probes for medical imaging and biosensor applications. However, zirconia particle agglomeration forms a major limitation to its use for biolabeling. In this backdrop, for the first time, well-separated zirconia nanocrystals were obtained in a Heliotron reactor (PROMES CNRS, France) via the solar physical vapor deposition (SPVD) method. As the raw material target for solar evaporation, zirconia nanopowders obtained via the sol–gel process were used. The luminescence and upconversion luminescence properties of the Sol Gel nanopowders were compared with those of the SPVD nanocrystals. Erbium …
All polarization-maintaining passively mode-locked fiber-ring ytterbium-doped laser; from net-normal to net-anomalous dispersion
2020
We investigated the behavior of a fiber-ring polarization-maintaining passively modelocked ytterbium-doped laser in a broad range of dispersion values; i.e., from highly net-normal to net-anomalous, with a special emphasis near the zero of chromatic dispersion. Different lengths of an ad hoc polarization-maintaining photonic crystal fiber were used as intracavity dispersion compensator to shift the operation of this laser from net-normal to the net-anomalous regime. The laser generated the shortest light pulses around the zero of dispersion: 6 ps / 7ps for −0.023 ps2 / 0.045 ps2 ; in both cases, pulses were not transform-limited, being theoretically possible an out-of-cavity recompression d…