title: Two-photon-excited fluorescence from silicate glass containing tantalum ions pumped by a near-infrared femtosecond pulsed laser.
abstract: We report a novel phenomenon in sodium-calcium-silicate glass doped with Ta(5+). Under irradiation with a 780 nm femtosecond pulsed laser, strong blue emission centered at about 420 nm could be observed. The spectral characteristics are similar to those pumped by ultraviolet photons. The log-log correlation between integrated emission intensity and pump power reveals that a two-photon absorption process is involved in the phenomenon. It is suggested that the presence of localized Ta(5+)5d(0) energy levels is responsible for the appearance of the blue emission. The results indicate that transition metal ions without d electrons play an important role in fields of optics when embedded into glass hosts.
authors.affiliation: Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto, Japan.
authors.forename: Xiangeng
authors.initials: X
authors.lastname: Meng
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Tanaka
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Murai
authors.forename: Koji
authors.initials: K
authors.lastname: Fujita
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Miura
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hirao