Visible Upconverter Based on $\hbox{Eu}^{3+}{\hbox{–}}\hbox{Yb}^{3+}$ Codoped $\hbox{TeO}_{2}{\hbox{–}} \hbox{ZnO}$ Glass

The zinc tellurite glasses (TZO) codoped with
$\hbox{Eu}^{3+}{\hbox{–}} \hbox{Yb}^{3+}$
ions have been prepared by the conventional melt and quenching technique. The photoluminescence spectra of the glass samples have been measured under 976-nm CW diode laser excitation. Several upconversion emission bands ranging from the blue to near infrared region have been detected in the codoped samples. The sensitized cooperative energy transfer process from the
$\hbox{Yb}^{3+}$
to
$\hbox{Eu}^{3+}$
ions and cross-relaxation process has been found to be responsible mechanism for the upconversion emissions in
$\hbox{Eu}^{3+}$
ions.