Spectroscopic properties and energy transfer parameters of 'Tm POT.3+' ions in gallium lanthanum sulfide glass - de Camargo, Andrea Simone Stucchi; Oliveira, Samuel L.; Sousa, Dione Fagundes de; Nunes, Luiz Antônio de Oliveira; Hewak, Daniel (Journal of Physics-Condensed Matter, 2002)