Low silica calcium aluminate glasses doped with erbium and yterbium to near and mid infrared lasers - Souza, D F de; Zonetti, L F C; Sampaio, J. A.; Baesso, Mauro Luciano; Gama, S; Nunes, Luiz Antônio de Oliveira (Brazilian Symposium on Glasses and Related Materials, 1998)