We report a novel phenomenon in sodium-calcium-silicate glass doped with Ta5+. Under irradiation with a 780 nm femtosecond pulsed laser, strong blue emission centered at about 420 mn 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. (c) 2006 Optical Society of America.