Optical properties of Ce(3+)/Tb(3+)-codoped borosilicate glass

Absorption spectra, luminescence spectra and luminescence decay time are investigated for a borosilicate glass containing low 0.1 wt pct Ce(3+) and high 15 wt pct Tb(3+) concentrations, together with the time-resolved luminescence. A broad absorption band due to parity allowed f - d transition is observed for Ce(3+). Sharp absorption bands are observed in 3100-1600 nm region which are due to the 7F6 - 7F(sub J) (J = 0, 1, 2, 3, 4) transition of Tb(3+), while much weak absorption bands due to the spin-forbidden 7F6 - 5D(sub J) (J = 2, 3, 4), 5G(sub J) (J = 3, 5, 6), 5LJ (J = 7, 8, 9, 10), 5HJ (J = 4, 5, 6), 5I(sub J) (J = 7, 8) and 5F(sub J) (J = 2, 4) transitions are observed in visible-UV region. By excitation with 266 nm laser line, two broad UV emission bands due to Ce(3+) are observed at 360 and 390 nm besides the intense green emission bands due to the 5D4 - 7F(sub J) (J = 6, 5, 4, 3) transition of Tb(3+) and weak blue emission bands due to the 5D3 - 7F(sub J) (J = 6, 5, 4, 3) transition. The decay time of the UV, blue and green emission is estimated to be 17 ns, 3.8 microsec, and 2.17 ms, respectively. The rise time of the green emission is about 4 microsec after the Ce(3+) emission and the Tb(3+) blue emission. No rise time is observed for the latter emission.