Room-temperature pulsed laser action has been obtained in chromium-activated forsterite (Cr:Mg2SiO4) for excitation of the near-infrared absorption band of the system by the 1064 nm radiation from a Nd:YAG laser. The characteristics of laser emission are similar to those observed for 532 nm pumping. It is suggested that the laser action is due to a ‘‘center’’ other than the trivalent chromium (Cr3+), presumably the tetravalent chromium (Cr4+).

Room-temperature vibronic pulsed laser action in trivalent chromium-activated forsterite (Cr3+:Mg2SiO4) is reported for the first time. The free-running laser emission is centered at 1235 nm of the broad 4T2→4A2 fluorescence band, and has a bandwidth of ∼22 nm.

We have shown that the broadband near-IR (NIR) fluorescence recently discovered in Bi-doped glasses is not specific due solely to Bi ions. Glasses doped with different 6p (Bi, Pb) and 5p (Sn, Sb) ions exhibit very similar behavior characterized by four major spectral peaks observed in two-dimensional excitation-emission plots and the lifetime of metastable level of about 400 micros. Our results challenge the existing models of optical centers in Bi-doped glasses. Point defect optical centers caused by the presence of 6p (Bi, Pb) and 5p (Sn, Sb) ions are proposed for the explanation of NIR emission in these laser materials.