Search results for "Glass"
showing 10 items of 1153 documents
Octave-spanning ultraflat supercontinuum with soft-glass photonic crystal fibers
2009
We theoretically identify some photonic-crystal-fiber structures, made up of soft glass, that generate ultrawide (over an octave) and very smooth supercontinuum spectra when illuminated with femtosecond pulsed light. The design of the fiber geometry in order to reach a nearly ultraflattened normal dispersion behavior is crucial to accomplish the above goal. Our numerical simulations reveal that these supercontinuum sources show high stability and no significant changes are detected even for fairly large variations of the incident pulse. Ministerio de Ciencia e Innovación (TEC2008-05490) and Generalitat Valenciana (GV/2007/043).
Solidification of a colloidal hard sphere like model system approaching and crossing the glass transition
2014
We investigated the process of vitrification and crystallization in a model system of colloidal hard spheres. The kinetics of the solidification process was measured using time resolved static light scattering, while the time evolution of the dynamic properties was determined using time resolved dynamic light scattering. By performing further analysis we confirm that solidification of hard sphere colloids is mediated by precursors. Analyzing the dynamic properties we can show that the long time dynamics and thus the shear rigidity of the metastable melt is highly correlated with the number density of solid clusters (precursors) nucleated. In crystallization these objects convert into highly…
Low loss microstructured chalcogenide fibers for large non linear effects at 1995 nm
2010
International audience; Microstructured optical fibers (MOFs) are traditionally prepared using the stack and draw technique. In order to avoid the interfaces problems observed in chalcogenide glasses, we have developed a new casting method to prepare the chalcogenide preform. This method allows to reach optical losses around 0.4 dB/m at 1.55 µm and less than 0.05 dB/m in the mid IR. Various As(38)Se(62) chalcogenide microstructured fibers have been prepared in order to combine large non linear index of these glasses with the mode control offered by MOF structures. Small core fibers have been drawn to enhance the non linearities. In one of these, three Stokes order have been generated by Ram…
Chalcogenide Microstructured Fibers for Infrared Systems, Elaboration, Modelization, and Characterization
2009
special issue " Fiber Optic Research in France " (Part III of III); International audience; Chalcogenide fibers present numerous possible applications in the IR field. For many applications, single mode fibers must be obtained. An original way is the realization of microstructured optical fibers (MOFs) with solid core. These fibers present a broad range of optical properties thanks to the high number of freedom degrees of their geometrical structure. In this context, we have developed MOFs for near and mid IR transmission with different geometries and properties such as multimode or endless single-mode operation, small or large mode area fibers. We have also investigated numerically the mai…
Mid-infrared 2000-nm bandwidth supercontinuum generation in suspended-core microstructured Sulfide and Tellurite optical fibers
2012
International audience; In this work, we report the experimental observation of supercontinua generation in two kinds of suspended-core microstructured soft-glass optical fibers. Low loss, highly nonlinear, tellurite and As2S3 chalcogenide fibers have been fabricated and pumped close to their zero-dispersion wavelength in the femtosecond regime by means of an optical parametric oscillator pumped by a Ti:Sapphire laser. When coupled into the fibers, the femtosecond pulses result in 2000-nm bandwidth supercontinua reaching the Mid-Infrared region and extending from 750 nm to 2.8 mu m in tellurite fibers and 1 mu m to 3.2 mu m in chalcogenide fibers, respectively.
Theoretical study of cascade laser in erbium-doped chalcogenide glass fibers
2010
International audience; A theoretical investigation of an innovative cascade laser source is performed. The main goal of the work is the design of a continuous-wave (CW) photonic crystal fiber (PCF) laser, based on an erbium-doped chalcogenide glass. Due to the comparable lifetimes of the 4I13/2, 4I11/2 and 4I9/2 erbium energy levels, the simultaneous emissions at the wavelengths close to 2.7 μm and 4.5 μm are obtained with a pump wavelength close to 806 nm (direct pumping into the level 4I9/2). This scheme could be useful to develop high efficiency, high beam-quality and compact Near-IR and Mid-IR oscillators with single-mode output for applications not only in surgery but also in spectros…
Mid-IR Fibres from Various Soft Glasses for Wide Band Sources
2013
Optical fibres from various soft glasses (tellurite, sulphide…) are designed, drawn and characterized with the purpose of light generation, through non linear effects, on a wide infrared band, targeting a 1-5 µm continuum source.
Gd 3+ -doped sol-gel silica glass for remote ionizing radiation dosimetry
2019
Gadolinium-doped silica glass was prepared, using the sol-gel route, for ionizing radiation dosimetry applications. Such a glassy rod was drawn to a cane at a temperature of 2000 °C. The structural and optical properties of the obtained material were studied using Raman, optical absorption, and photoluminescence spectroscopies. Thereafter, a small piece of this Gd-doped scintillating cane was spliced to a transport passive optical fiber, allowing the remote monitoring of the X-ray dose rate through a radioluminescence (RL) signal. The sample exhibited a linear RL intensity response versus the dose rate from 125 µGy(SiO2)/s up to 12.25 Gy/s. These results confirm the potentialities of this m…
Nanoindentation and Raman Spectroscopic Study of Graphite Irradiated with Swift238U Ions
2012
Modifications of the structure and mechanical properties of the isotropic fine-grained graphite R6650 irradiated with 2.6 GeV 238U ions at fluences up to 1013 ions/cm2 at room temperature are studied. A strong ion-induced increase of Young's modulus and hardness is observed that points to the formation of a hard form of carbon. Raman spectra ascertain the disordering of graphite and its transformation to glassy carbon.
Triphenyl group containing molecular glasses of azobenzene for photonic applications
2016
Abstract D-π-A type organic molecules have attracted considerable attention of scientists due to their potential applications in nonlinear optics and holographic data storage as light, flexible and low-cost photonic materials. To provide a better understanding on the relation between the compound chemical structure and their physical properties necessary for the mentioned purposes, eight glassy triphenyl group containing derivatives of azobenzene with incorporated 5,5-dimethylcyclohex-2-enylidene or 4H-pyran-4-ylidene structural fragments and dicyanomethylene, indene-1,3-dione and pyrimidine-2,4,6(1H,3H,5H)-trione acceptor groups have been synthesized and investigated. Thermal stability of …