Random laser emission from neodymium doped zinc tellurite glass-powder presenting luminescence concentration quenching

Abstract

Random Laser (RL) operation is reported for the first time in neodymium ions (Nd3+) doped zinc-tellurite (TZO) glass-powders. TZO glass was prepared by conventional melt-quenching technique and polydisperse micrometric grains with varying Nd3+ concentrations were obtained after milling. The samples were excited by a pulsed (5 ns, 5 Hz) source at 585 nm, in resonance with transition 4I9/2 → {4G5/2, 2G7/2}. For low excitation intensities all powder samples showed a broad emission band centered at 1068 nm (corresponding to transition 4F3/2 → 4I11/2) with microseconds decay time. Random lasing was only achieved for samples with Nd2O3 concentrations higher than 2.0 wt. %, despite the occurrence of Luminescence Concentration Quenching (LCQ). Excitation pulse energy thresholds for laser action were observed at 8 and 5 μJ/mm2 for samples doped with 5.0 and 10.0 wt. % of Nd2O3, respectively. The glassy-grains act simultaneously as gain medium and scatterers and the RL feedback mechanism is attributed to the light reflections in the grains-air interfaces. Above the laser threshold, we observed RL emission at 1068 nm, in the nanosecond range. The experimental data are supported by a rate-equation model that corroborates the main results. The results herein reported show that TZO glass may be employed as promising disordered medium for operation of RL sources.