Marcel Poulain

Verres fluores au tetrafluorure de zirconium proprietes optiques d'un verre dope au Nd3+

Abstract Glass formation has been observed in the ZrF4BaF2NaF system around the composition 50 % ZrF4, 25 % BaF2, 25 % NaF. A Nd3+ doped glass obtained by dissolving NdF3 in the previous material has been studied. Absorption spectra in the region 4 I 9 2 → 2 P 1 2 , I.R. fluorescence spectra and lifetime measurement of the 4 F 3 2 level show a good protection of Nd3+ against the fluorescence quenching.

Preparation and optical properties of neodymium fluorozirconate glasses

Abstract A vitreous domain is investigated in the ternary system ZrF 4 BaF 2 NdF 3 . A typical composition for a glass is 60% ZrF 4 , 34% BaF 2 , 6% NdF 3 ; it can be extended to other rare earths. Several spectroscopic properties of this new Nd glass are reported: absorption and fluorescence spectra, fluorescence lifetime and refractive index. The properties of fluorozirconate glasses are compared with those of other known glasses for laser applications.

Mid-infrared supercontinuum generation to 4.5 μm in ZBLAN fluoride fibers by nanosecond diode pumping

A mid-infrared supercontinuum (SC) is generated in ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF...) fluoride fibers from amplified nanosecond laser diode pulses with a continuous spectrum from approximately 0.8 microm to beyond 4.5 microm. The SC has an average power of approximately 23 mW, a pump-to-SC power conversion efficiency exceeding 50%, and a spectral power density of approximately -20 dBm/nm over a large fraction of the spectrum. The SC generation is initiated by the breakup of nanosecond laser diode pulses into femtosecond pulses through modulation instability, and the spectrum is then broadened primarily through fiber nonlinearities in approximately 2-7 m lengths of ZBLAN fiber. The SC long-wavelength edge is consistent with the intrinsic ZBLAN material absorption.

Nouveaux verres fluores

Abstract New fluoride glasses have been obtained in the ZrF 4 ThF 4 BaF 2 systems. Large samples have been prepared in order to determine some physical properties. Optical transmission range lies from 0,22 to 7μ, the refractive index is about 1, 53 and can be modulated by chemical composition. Glass temperature, crystallization and melting temperature have been measured.

Heavy metal oxide glasses: preparation and physical properties

Abstract Heavy metal oxide glasses have been investigated in the following systems: TeO2–PbO–PbCl2, TeO2–ZnO, Ga2O3–PbO–Bi2O3 glasses with low OH concentration were prepared. The influence of the processing conditions on the color, the structure and the optical properties of the prepared samples was also assessed. Mixtures of starting oxides were melted in various reactive conditions using Pt, Au, SiO2 and alumina crucibles. A set of physical measurements including chemical and X-ray analysis, scanning electron microscopy, absorption spectroscopy, ultraviolet and infrared absorption edges and thermo-physical properties, were carried out. Samples were doped with Nd, Pr and Er rare earth ions. Low temperature photoluminescence spectra show the expected rare earth transitions and the broad band emission of the base glass.

Etude de la conduction ionique de verres a base de ZrF4

Abstract The electrical and dielectric properties of new ZrF 4 based glasses have been studied in the frequency and temperature ranges 5Hz-500kHz and 130–280°C. Transport number measurements following Tubants method showed that the glasses investigated are F − conductors. The conductivities and activation energies for conduction are about 10 −6 (Ωcm) −1 at 200°C and 18 kcal.mole −1 respectively. Preliminary interpretation of the change of conductivity with composition is given.

Lanthanum fluorozirconate glasses

Abstract Investigations in the ZrF 4 -BaF 2 -LaF 3 ternary system show the existence of a vitreous area in the range: ZrF 4 : 56–67%, BaF 2 :25–36%, LaF 3 :3–13%. For a standard glass of molar composition 0.62 ZrF 4 , 0.30 BaF 2 , 0.08 LaF 3 , the refractive index is 1.5248 with the glassy transition occuring at 310°C and fusion occuring at 545°C. Quaternary glasses have been obtained by including a M F fluoride ( M = Na or Li) with the previous ternary glass according to the formula: (0.62 – 0.4 x )ZrF 4 (0.30 –0.5 x )BaF 2 (0.088 – 0.1 x )LaF 3 xM F. Evolution of glassy transition, refractive index, density and molar refractivity is discussed in relation to the structural role of the Na + and Li + ions. In these zirconium fluoride glasses, lithium could act as a network former at low concentration and as a network modifier at higher concentration.

Structural studies on TeO2-PbO glasses

Abstract Binary tellurite-based glasses in the TeO 2 –PbO system were prepared and its structure investigated by means of Raman Scattering and X-ray Absorption Spectroscopy. Both spectroscopies indicate strong modifications of the first coordination shell around tellurium atoms when the PbO content increases revealing for lead its glassy network modifier role. Also, Pb L 3 -edge EXAFS measurements reveal this structural role played by lead atoms, but the presence of a medium range order contribution indicates that lead also participates to the glassy network formation.

Power scalable mid-infrared supercontinuum generation in ZBLAN fluoride fibers with up to 1.3 watts time-averaged power

Mid-infrared supercontinuum (SC) extending to ~4.0 mum is generated with 1.3 W time-averaged power, the highest power to our knowledge, in ZBLAN (ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF...) fluoride fiber by using cladding-pumped fiber amplifiers and modulated laser diode pulses. We demonstrate the scalability of the SC average power by varying the pump pulse repetition rate while maintaining the similar peak power. Simulation results obtained by solving the generalized nonlinear Schrödinger equation show that the long wavelength edge of the SC is primarily determined by the peak pump power in the ZBLAN fiber.

Optical spectroscopy and frequency upconversion properties of Tm3+ doped tungstate fluorophosphate glasses

Tungstate fluorophosphate glasses of good optical quality were synthesized by fusion of the components and casting under air atmosphere. The absorption spectra from near-infrared to visible were obtained and the Judd–Ofelt parameters determined from the absorption bands. Transition probabilities, excited state lifetimes and transition branching ratios were determined from the measurements. Pumping with a 354.7 nm beam from a pulsed laser resulted in emission at 450 nm due to transition 1D2→3F4 in Tm3+ ions and a broadband emission centered at ≈550 nm attributed to the glass matrix. When pumping at 650 nm, two emission bands at 450 nm (1D2→3F4) and at 790 nm (3H4→3H6) were observed. Excitation spectra were also obtained in order to understand the origin of both emissions. Theoretical and experimental lifetimes were determined and the results were explained in terms of multiphonon relaxation.