Enhancement of upconversion in Nd3+/Yb3+ co-doped tellurite glass microspheres produced by a plasma arc

Abstract

In this paper, we report enhanced upconversion emission in Nd${}^{3+}$ and Yb${}^{3+}$ co-doped tellurite glass microspheres, fabricated via the plasma torch method. The upconversion efficiency was found to be much stronger in the produced microspheres in respect to the precursor glass, which we attribute to the change of luminiscence properties induced by the microsphere production process. The samples were excited using a 980 nm laser, and the upconversion behavior was analyzed under increasing power using Raman spectroscopy. The rapid thermal quenching of the glass powder during microsphere formation significantly enhanced the upconversion efficiency observed in the spherical samples. Emission and absorption characteristics were comprehensively analyzed using Raman and UV–visible spectroscopy, respectively. Furthermore, lifetime luminescence measurements were performed at emission wavelengths of 590 nm, 870 nm, and 980 nm.