Green-to-red light tuning by up-conversion emission via energy transfer in Er3+–Tm3+-codoped germanium–tellurite glasses

• Published in: Journal of non-crystalline solids 2014-06, Vol.392-393 (C), p.45-50
• Main Authors: Rivera, V.A.G., Ledemi, Y., El-Amraoui, M., Messaddeq, Y., Marega, E.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Energy transfer; Exact sciences and technology; Excited state absorption; Fundamental areas of phenomenology (including applications); Germanium–tellurite glass; Glasses (including metallic glasses); Lasers; Materials science; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Optics; Photoluminescence; Physics; Semiconductor lasers; laser diodes; Specific materials; Upconversion emission
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2014.04.007

The luminescence properties through up-conversion emission process of Er3+–Tm3+-codoped germanium–tellurite glasses was carefully investigated by using UV–visible–near-infrared absorption spectroscopy, emission spectroscopy and lifetime measurement under near-infrared laser diode excitation at 976nm. The glass samples were prepared by the conventional melt-casting technique. The Er3+ and Tm3+ ions act in this glass matrix as donor and acceptor, respectively, and can generate under 976nm laser excitation a visible emission tunable from the green to the red color by varying the Tm3+ ion concentration. Two mechanisms are involved to obtain this up-conversion emission and its tunability from the green to the red light: (i) the excited state absorption (ESA) of Erbium ions Er3+:(4I11/2→4F7/2) and; (ii) the energy transfers (ETs) between Erbium Er3+ and Thulium Tm3+ ions. Such processes were studied by means of quantum efficiency and ET probability. It was verified that both of them depend on the Tm3+ ion concentration. The relative intensity of the red emission was increased up to 2.6 times for the glasses containing 0.1mol% and 1.0mol% of Thulium oxide Tm2O3 if compared with the Erbium Er3+ single doped glass. The spectroscopic study presented in this work has permitted to fully describe the color rendering, ranging from green to red through yellow and orange, of the light emitted by the Er3+–Tm3+-codoped germanium–tellurite glasses under a low power laser diode excitation at 976nm (30mW). •Visible emission from green to red color in Er3+–Tm3+ germanium–tellurite glass•Two mechanisms are involved to obtain this NIR for the visible up-conversion emission.•Intensity in the UC emission is favored by the absorption of three excitation photons.•The color tunability emission makes these glasses promising for photonic devices.