Spectroscopic studies of Nd 3+ doped lead tungsten tellurite glasses for the NIR emission at 1062 nm M. Venkateswarlu a , Sk. Mahamuda a , K. Swapna a , M.V.V.K.S. Prasad a , A. Srinivasa Rao a,b,⇑ , A. Mohan Babu c , Suman Shakya d , G. Vijaya Prakash d a Department of Physics, KL University, Green Fields, Vaddeswaram 522 502, Guntur (Dt.), AP, India b Department of Applied Physics, Delhi Technological University, Bawana Road, New Delhi 110 042, India c Department of Physics, Chadalawada Ramanamma Engineering College, Renigunta Road, Tirupati 517 506, AP, India d Nanophotonics Laboratory, Department of Physics, Indian Institute of Technology-Delhi, Hauz Khas, New Delhi 110 016, India article info Article history: Received 18 June 2014 Received in revised form 1 October 2014 Accepted 16 October 2014 Available online 16 November 2014 Keywords: Amorphous materials Glasses JO parameters Optical materials Luminescence Optical properties abstract Lead Tungsten Tellurite (LTT) glasses doped with different concentrations of Nd 3+ ions were prepared by using the melt quenching technique to study the absorption, emission and decay spectral profiles with an aim to understand the lasing potentialities of these glasses. From the absorption spectra, the Judd–Ofelt (J–O) parameters are evaluated and in turn used to calculate the transition probability (A R ), total transition probability (A T ), radiative lifetime (s R ) and branching ratios (b R ) for prominent emission levels of Nd 3+ . The emission spectra recorded for LTT glasses gives three emission transitions 4 F 3/2 ? 4 I 9/2 , 4 F 3/2 ? 4 I 11/2 and 4 F 3/2 ? 4 I 13/2 for which effective band widths (Dk P ) and stimulated emission cross-sections (r se ) are evaluated. Branching ratios (b R ) measured for all the LTT glasses show that 4 F 3/2 ? 4 I 11/2 transition is quite suitable for lasing applications. The intensity of emission spectra increases with increase in the concentra- tions of Nd 3+ up to 1.0 mol% and beyond concentration quenching is observed. Relatively higher emission cross-sections and branching ratios observed for the present LTT glasses over the reported glasses suggests the feasibility of using LTT glasses for infrared laser applications. From the absorption, emission and decay spectral measurements, it was found that 1.0 mol% of Nd 3+ ion concentration is aptly suitable for LTT glasses to give a strong NIR laser emission at 1062 nm. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction In recent years, rare earth doped materials are playing a vital role in the modern optical technology as an active constituents to produce low price integrated laser sources, integrated optical amplifiers, 3D display devices, sensors, up-conversion fibres and low loss components [1]. The above mentioned applications pos- sessed by the rare earth doped materials have stimulated the research on rare earth doped glasses [2–6]. Among different rare earth ions, neodymium ion is one of the utmost efficient ions used to prepare solid-state lasers because of its intense emission at 1060 nm [7]. For this reason, trivalent neodymium (Nd 3+ ) ion doped variety of crystals and glasses were studied extensively under 808 and 885 nm laser diode excitation with an aim to develop high power NIR (at 1060 nm) solid state lasers [8,9]. Different glass hosts like borates, phosphates, germanates, vana- dates and tellurite families have been studied extensively for this purpose [10–14]. Among all oxide glasses, Lead Tungsten Tellurite (PbF 2 –WO 3 –TeO 2 ) glass system (LTT) has unique optical proper- ties. Tellurite based glasses besides having high linear and third order nonlinear optical constants (nonlinear refractive indices), can possess high mechanical stability, good corrosion resistance and low phonon energies equal to 750 cm 1 . All these novel prop- erties make them to have their transitions range extended up to mid IR (5–6 lm) region. Tellurite based glasses are also having good capacity to accept lanthanide dopants at different concentra- tions [15]. The low phonon energy, extended transmission range and high refractive index of tellurite glasses allow the observation of laser emission from rare earth ions in a wide spread spectral range [5,16–20]. Such materials are also useful in optical wave- guides. Tungsten oxide (WO 3 ) is a precise noble semi conducting and transition-metal oxide which has fascinated considerable attention for several years. It is also one of the most examined and used material for electro-chromic and photo-chromic devices in which colouration and bleaching can be reversibly obtained by http://dx.doi.org/10.1016/j.optmat.2014.10.031 0925-3467/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author at: Department of Applied Physics, Delhi Technological University, Bawana Road, New Delhi 110 042, India. Tel.: +91 85860 39007; fax: +91 01127871023. E-mail address: drsrallam@gmail.com (A. Srinivasa Rao). Optical Materials 39 (2015) 8–15 Contents lists available at ScienceDirect Optical Materials journal homepage: www.elsevier.com/locate/optmat