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Achieving tuneable photoluminescence via controlled co-doping of rare earth ions in lithium niobate based glasses are challenging. A series of Er3+/ Nd3+ co-doped tellurite glasses of composition (70-x-y) TeO2 – 15 Li2CO3 – 15 Nb2O5 – (x) Er2O3 – (y) Nd2O3 with x = 0; 1.0 mol % and 0 ≤ y ≤ 1.0 mol % are prepared using melt quenching technique. The influence of co-dopants on the emission properties is analyzed and discussed using partial energy level diagram of rare earth ions. The dopants concentration dependent physical properties such as refractive index, molar volume, density, polarizability and molar refractions are determined. The down-converted luminescence spectra for 2G9/2 à4I9/2 transition reveal a strong green emission band centred at 497 nm is attributed to the energy transfer from erbium to neodymium ion. The emission spectra exhibit five prominent peaks centred at 497, 539, 553, 616 and 634 nm corresponding to the transitions from 2H11/2, 4S3/2 and 4F9/2 excited states to the ground state of Er3+ ion and the transitions from 2G9/2, 2G7/2, 2H11/2 and 4F9/2 excited states to ground state of Nd3+ ion. The highest intensity is achieved for x = y = 1.0 mol%. The excellent luminescence response suggests that our glasses may be nominated for solid state lasers and other photonic applications.

Optimizing the rare earth doping in inorganic binary glasses for tuneable structural and optical properties is ever-demanding for lasing glass. A series of Er3+ and Nd3+ doped lithium niobate tellurite glasses with compositions of (70-x-y)TeO2–15Li2CO3–15Nb2O5–(x)Er2O3–(y)Nd2O3, where x = 0.0, 1.0 mol % and 0 ≤ y ≤ 1.0 mol% are synthesized using melt-quench technique. Influence of Nd3+ ion concentrations on physical and optical behaviour is examined. X–Ray diffraction pattern confirm the amorphous nature of glasses. The strong dependence of spectral properties on rare-earth dopant indicates the alteration in structures and bonding of glass network. The structural properties of the glass represented by the FTIR spectrum indicate that as Nd2O3 content increases, the sharp infrared absorption peaks are shifted from 474.7 cm-1 to 499.4 cm-1. These peaks are due to Nb-O, Te-O-Te and O-Te-O bond linkage bending vibrations. For TeO4 trigonal bipyramid, the peak occurred at 676.5 cm-1 whereas for TeO3 trigonal pyramid, two infrared band peaks are found at 787.5 cm-1 and 887.6cm-1, respectively. The absorption peaks around 1382.7 cm-1 is due to the Te – O – Nb stretching vibration while peaks at 1635.5cm-1 and 3411.7 cm-1 are due to the stretching vibrations of the hydroxyl group participating in the strong metal bonding as well as in the hydrogen bonding, respectively.

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