Spectral study of the stimulated emission of Nd^3+ in fluorotellurite bulk glass

Abstract

Abstract:In this work we present, for the first time to our knowledge, laser emission under wavelength selective laser-pulsed pumping in Nd 3+ -doped TeO 2 -ZnO-ZnF 2 bulk glass for two different Nd 3+ concentrations. The fluorescence properties of Nd 3+ ions in this matrix which include, JuddOfelt calculation, stimulated emission cross-section of the laser transition and lifetimes are also presented. The site-selective emission and excitation spectra along the 4 I 9/2 → 4 F 3/2 absorption band show the inhomogeneous behaviour of the crystal field felt by Nd 3+ ions in this fluorotellurite glass which allows for spectral tuning of the laser output pulse as a function of the pumping wavelength. The emission cross-section obtained from the Judd-Ofelt analysis and spectral data (4.9x10 −20 cm 2 ) is in fairly good agreement with the value obtained from the analysis of the laser threshold data (4x10 −20 cm 2 ).

Laser emission of a Nd-doped mixed tellurite and zinc oxide glass

“…True continuous-wave (CW) laser action is achieved by pumping the sample with a CW Ti:sapphire laser inside a standard two-mirror laser cavity. A low laser threshold of 8 mW and a laser slope efficiency of 21% could be obtained for an output coupler transmission of 2.7%, which is an encouraging improvement compared to what was reported in the past with other Nd-doped tellurite bulk glasses [3][4][5][6][7].…”

“…In order to minimize the nonradiative multiphonon relaxations and optimize the quantum efficiency of the 4 F 3∕2 → 4 I 11∕2 emission of Nd 3 , it is also suitable to work with Nd 3 -doped host materials with low phonon frequencies and low contents of OH impurities. In that sense, laser emission of Nd 3 in glasses has been reported in fluorides [11][12][13], chalcogenides [14], aluminosilicates [15], germanates [16], and, as just mentioned, in tellurite glasses [3][4][5][6][7]. Among oxi-tellurites, the TeO 2 -ZnO glass which is considered here in the present article combines good mechanical stability, chemical durability, high linear and nonlinear refractive indices, together with low phonon energies (∼750 cm −1 ), a wide transmission window (0.4-6 μm), and a high rare-earth solubility [10,17,18].…”

“…This is the case for the instance of the recently developed CaF 2 laser crystal codoped with Nd 3 and Lu 3 or Y 3 ions, because of the conjunction of good thermo-mechanical properties, typical of crystals, and broadband spectral properties, typical of glasses [2]. This is also the case for some Nd-doped nonlinear tellurite glasses [3][4][5][6][7][8][9], because of a very interesting combination of large nonlinear refractive index (25 times larger than that of silica) and wide transmittance range, and also because of a low maximum phonon frequency which allows rare-earth ion laser emissions in a wide spectral range [10].…”

Er3+-doped fluorotellurite thin film glasses with improved photoluminescence emission at 1.53 µm

“…Te, Er, Zn, and O contents were determined by Rutherford backscattering spectrometry (RBS) using two different incident beams (H + at 1.5 MeV and 6 Li + at 3 MeV) and the SIMNRA code to analyze the experimental spectra [29], while Proton induced Gamma-ray emission (PIGE) was used to determine the fluorine content in the samples by using an incident proton beam at 2.3 MeV and looking at the Gamma ray peaks at 110 y 197 keV coming from the 19 F(p,p'γ) 19 F reaction [30]. The oxidation state of the cations was measured by X-ray photoelectron spectroscopy (XPS).…”

“…In addition, fluorotellurite glasses show an enhancement of RE radiative transition rates and a spectral broadening of their photoluminescence (PL) emission bands due to their high refractive index and the variety of sites for the RE ions [7,16]. In particular, fluorotellurite glasses belonging to the TeO 2 -ZnO-ZnF 2 system are promising RE hosts to be used in active optical applications, since they present high absorption cross-section [13,17], broad emission (≈ 150 nm) that covers S, C+L and U telecommunication bands when codoped with Er 3+ and Tm 3+ [18], and laser emission has been demonstrated in the case of Nd 3+ doped fluorotellurites [19]. Finally, we have recently reported the synthesis of fluorotellurite glass-ceramics, which opens a new range of applications [20].…”