A marked enhancement of the intensity of the 0.98μ emission of Yb3+ ions in porous material was obtained by pre-annealing in O2 or H2 before Yb3+ ion incorporation and post-doping annealing. The luminescence intensity exhibited a slight temperature quenching, decreasing from 20 to 300K by a factor of about 10. Time-decay measurements showed that there were 2 major Yb3+-related luminescence centers in Yb-doped porous material. One was a fast-decaying center with a decay time of about 30μs at 20K, which decreased rapidly with increasing temperature. The other was a slowly-decaying center with an almost temperature-independent decay time of some 400μs. The latter was responsible for the slight temperature-quenching of the Yb3+-related 0.98μ emission.

T.Kimura, Y.Nishida, A.Yokoi, R.Saito: Journal of Applied Physics, 1998, 83[2], 1005-8