NIR emission from Nd3+-doped Na2O + Li2O + CdO + B2O3 glasses: a study of structural, physical and radiative properties

Abstract

By changing the concentration of Nd3+ ions, the alkalicadmino borate glasses with molar composition of 15Na2O + 15Li2O + 20CdO + 50B2O3 (NaLiCdBNd) were fabricated by the suddenly melt-quenching technique. The XRD pattern and Raman spectroscopy indicate the amorphous nature and determinations of the various vibrational modes for undoped NaLiCdB glass, respectively. The fundamental radiative properties such as radiative emission probability (AR), branching ratio (βR), and radiative lifetime (τR), including effective line width (Δλeff) and stimulated emission cross-section (σemi), were calculated for Nd3+:4F3/2 → 4I9/2,11/2,13/2 transitions by following the Judd–Ofelt parameters (Ω2,4,6), and infrared (NIR) emission spectra. The optical bandgap energy corresponding to the direct, (αhυ)2 and indirect, (αhυ)1/2 allowed transitions was found to be decrease in the order of 3.92–3.86 eV and 3.51–3.36 eV by increasing of Nd3+ ions. Under 808 nm excitation, the NIR emission spectra show a strong 4F3/2 → 4I11/2 (1060 nm) transition, and two less intensity of 4F3/2 → 4I9/2(889 nm) and 4F3/2 → 4I13/2 (1332 nm) emission transitions. The lifetimes of 4F3/2 level are found to decrease with respect to increase in Nd3+ concentration and the decay curves of the title glasses exhibit non-exponential nature. The higher optical gain (175.2 × 10−25 cm2s) and low threshold (1.23 × 108 W/m2) together with superior stimulated emission cross-section (5.69 × 10−20 cm2) and 87% of quantum efficiency for NaLiCdBNd05 glass show the potential laser performance at 1.06 μm for high gain-low threshold laser materials.