Fluorescence properties of Er3+-doped sol-gel glasses

Er3+-doped sol-gel silica was prepared and its fluorescence spectra measured. The samples were prepared from tetraethoxysilane (TEOS), water and ethanol, using Er(NO3)(3) . 5H(2)O as the Er3+ precursor. Transparent gel-glasses were obtained from two synthesis schemes (molar ratios of TEOS/H2O/C2H5OH = 1/4/4 and 1/16/0) for Er2O3 concentrations ranging from 0.1 to 10.0 wt%. All samples exhibited visible (S-4(3/2) --> I-4(15/2) and F-4(9/2) --> I-4(15/2)) and infrared fluorescence at room temperature, The Er3+ fluorescence intensity was observed to increase with increasing heat treatment temperature of a sample. The presence of Al3+ led to a broadening and blue shift of the Er3+ I-4(13/2) --> I-4(15/2) fluorescence. These effects are consistent with a more random site distribution and a more ionic bonding environment for Er3+ in the glass.