White light emission under 980 nm and Judd-Ofelt analysis of tellurite-zinc glasses doped with Er3+-Yb3+-Tm3+

• Autor(a) principal: Calderón, Gaston Lozano
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/76/76132/tde-15052020-133107/
• topic: Conversão ascendente; Energy transfer; Judd-Ofelt; Judd-Ofelt; Luz branca; Micro-parameters; Micro-parâmetros; Rare-earths; Tellurite; Telurito; Terras raras; Transferência de energia; Up-conversion; White light

In this dissertation, tellurite-zinc glasses doped with Tm3+, Yb3+ and Er3+ were fabricated by conventional melt-quenching method and characterized by absorption spectroscopy, refractive index, lifetime measurements, excitation, luminescence and up-conversion spectroscopy. Tunable white to blue light emission based on the colour mixing of red, green and blue light was observed in the triply-doped samples via up-conversion under 980 nm and by adjusting the laser excitation intensity. The balancing of the relative intensity of each colour is provided by the energy transfer process between the rare-earth ions. Moreover, luminescence spectroscopy was performed with a 405 nm laser to further understand the energy transfer mechanism. According to the Judd-Ofelt theory, the intensity parameters (&Omega;2, &Omega;4 and &Omega;6) of Er3+ and Tm3+ for all samples present the trend &Omega;2 < &Omega;4 < &Omega;6. These parameters are related to the bonding and local structure in the vicinity of the rare-earth ions, which give information regarding to physical and chemical properties. The spectroscopic parameters were calculated with the Judd-Ofelt theory and the energy transfer micro-parameters (critical radius of interaction and energy transfer coefficient) were determined by the Dexter model. Such results shall be used to give a comprehensive explanation for the energy transfer process between these rare earth ions.