Spectroscopic properties of water free Nd2O3-doped low silica calcium aluminosilicate glasses
ABSTRACT In this work, low silica calcium aluminosilicate glasses (LSCA) doped with different concentrations of Nd2O3 were prepared under vacuum conditions and investigated through spectroscopic measurements. UV, visible and near IR optical absorption spectra, IR luminescence spectra, and fluorescent time decay were measured. Judd–Ofelt model was used in conjunction with these data to calculate intensity parameters and ), emission cross-section, radiative lifetime, branching ratio and fluorescence quantum efficiency. The up-conversion properties of Nd3+ were investigated following excitation, and both visible and UV up-conversion have been observed. These results combined with its high fluorescence quantum efficiency and excellent mechanical properties, suggest that this glass may be a candidate to be used as laser host material for near IR with a further possibility of application in the UV and visible spectral regions.
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ABSTRACT: In this work the time resolved thermal lens method is combined with interferometric technique, the thermal relaxation calorimetry, photoluminescence and lifetime measurements to determine the thermo physical properties of Nd(2)O(3) doped sodium zincborate glass as a function of temperature up to the glass transition region. Thermal diffusivity, thermal conductivity, fluorescence quantum efficiency, linear thermal expansion coefficient and thermal coefficient of electronic polarizability were determined. In conclusion, the results showed the ability of thermal lens and interferometric methods to perform measurements very close to the phase transition region. These techniques provide absolute values for the measured physical quantities and are advantageous when low scan rates are required.Optics Express 01/2009; 16(26):21248-55. · 3.55 Impact Factor
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ABSTRACT: By means of ADE-FDTD method, this paper investigates the electromagnetic modelling of a rib-loaded waveguide composed of a Nd3+ doped Silicon Rich Silicon Oxide active layer sandwiched between a SiO2 bottom cladding and a SiO2 rib. The Auxilliary Differential Equations are the rate equations which govern the levels populations. The Finite Difference Time Domain (FDTD) scheme is used to solve the space and time dependent Maxwell equations which describe the electromagnetic field in a copropagating scheme of both pumping (λpump = 488 nm) and signal (λsignal = 1064 nm) waves. Such systems are characterized by extremely different specific times such as the period of electromagnetic field ~ 10-15 s and the lifetimes of the electronic levels between ~ 10-10s and ~ 10-4 s. The time scaling method is used in addition to specific initial conditions in order to decrease the computational time. We show maps of the Poynting vector along the propagation direction as a function of the silicon nanograin (Si-ng) concentrations. A threshold value of 1024 Si-ng m-3 is extracted below which the pump wave can propagate so that a signal amplication is possible.Nanoscale Research Letters 01/2011; 6(1):278. · 2.52 Impact Factor
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ABSTRACT: Optical absorption and luminescence spectra as well as luminescence kinetics of the Nd 3+ centres in glasses with Ca 3 Ga 2 Ge 3 O 12 :Nd composition, containing 0.2 and 1.0 wt% of the Nd 2 O 3 were presented and analysed. The oscillator strengths and phenomenological intensity parameters Ω t (Ω 2 , Ω 4 , and Ω 6) were obtained using standard Judd–Ofelt theory. Calculated Ω t parameters, radiative transitions rates, branching ratios and radiative lifetime for Nd 3+ centres in the glass with Ca 3 Ga 2 Ge 3 O 12 composition were analysed and compared with corresponding Nd 3+ parameters in their crystalline analogue with garnet structure. Experimental lifetimes are compared with those calculated, and quantum efficiency of Nd 3+ centres from 4 F 3/2 emitting level in the glass with Ca 3 Ga 2 Ge 3 O 12 composition is estimated. Incorporation peculiarities and local structure of Nd 3+ luminescence centres in the glass with Ca 3 Ga 2 Ge 3 O 12 composition and corresponding Ca 3 Ga 2 Ge 3 O 12 :Nd 3+ garnet laser crystals are considered. On the basis of extended X-ray absorption fine structure (EXAFS) spectra (L 3 -edge) of rare-earth elements analysis it has been shown that Nd 3+ luminescence centres in the CaO–Ga 2 O 3 –GeO 2 glass network occupy structural sites with the coordination number to oxygen N = 6.Optica Applicata 01/2008; · 0.54 Impact Factor