Abstract
Erbium-doped tin dioxide (SnO2:Er3+) was obtained by the sol-gel method. Spectroscopic properties of the SnO2:Er3+ are analyzed from the Judd-Ofelt (JO) theory. The JO model has been applied to absorption intensities of Er3+ ((4)f(11)) transitions to establish the so-called Judd-Ofelt intensity parameters: ohm(2), ohm(4), and ohm(6). With the weak spectroscopic quality factors ohm(4)/ohm(6), we expect a relatively prominent infrared laser emission. The intensity parameters are used to determine the spontaneous emission probabilities of some relevant transitions, the branching ratios, and the radiative lifetimes of several excited states of Er3+. The emission cross section (1.31x10-20 cm2) is evaluated at 1.54 mu m and was found to be relatively high compared to that of erbium in other systems. Efficient green and red up-conversion luminescence were observed, at room temperature, using a 798-nm excitation wavelength. The green up-conversion emission is mainly due to the excited state absorption from I-4 (11/2), which populates the F-4 (3/2,5/2) states. The red up-conversion emission is due to the energy transfer process described by Er3+ (I-4(13/2))+Er3+(I-4(11/2)) -> Er3+(F-4(9/2))+Er3+ (I-4 (15/2)) and the cross-relaxation process. The efficient visible up-conversion and infrared luminescence indicate that Er3+-doped sol-gel SnO2 is a promising laser and amplifier material.