Structural, luminescence and NMR studies on Nd3+-doped sodium–calcium-borate glasses for lasing applications

Abstract

In this work, Neodymium (Nd3+) -doped borate glasses were synthesised by melt-quenching method and their structural as well as optical properties were analysed through XRD, Raman, NMR, DSC, UV–Visible, luminescence and decay studies for the possible application as laser gain medium. DSC and XRD results revealed that the glasses have high transition temperature and are in amorphous nature, respectively. The vibrational characteristics of the host matrices as well as the effect of Nd3+ incorporation were analysed by using Raman spectra, which exhibit majorly borate groups as supported by NMR results. The band gap energy of the glasses decreases with an increase in Nd3+ concentration. Using Judd-Oflet theory the characteristic intensity parameters (Ωλ, λ = 2, 4 and 6) were calculated and further used for calculating the various radiative parameters from the emission spectra. The emission cross-section (σem) was estimated as high as 1.15 × 10−20 cm2 from the Füchtbauer–Landenburg (FL) equation for the dominant 4F3/2→4I11/2 (1056 nm) transition. The effect of Nd3+ concentration on the lifetime of the 4F3/2 luminescent level was analysed from the decay curve analyses. From which, the corresponding quantum efficiency (η) was estimated and found as high as 54%. The investigated result suggests the prepared glasses can be utilized as gain medium to generate laser at around 1.05 μm.