Spectroscopic studies of rare earth ions in silica glasses prepared by the sol-gel process

Spectroscopic properties of Tb3+, Eu3+, Er3+ and Pr3+ ions in silica glasses prepared by sol-gel techniques have been investigated. The results showed that the emission spectrum of Tb3+ consisted of transitions from the D-5(4) excited level and the D-5(4) excited level to the F-7 manifold of the ground state. The emission bands of Eu3+, Er3+ and Pr3+ consisted of transitions from the single excited level (D-5(0) excited level of Eu3+, S-4(3/2) excited level of Er3+ and D-1(2) excited level of Pr3+) to the manifold of the ground state. It was also found that the emission intensities of rare earth ions in silica glasses were significantly dependent upon the energy gap between the emitting level and the next level. The relative emission intensities of rare earth ions in silica glasses followed the series Tb3+ > Eu3+ > Er3+ > Pr3+.