Influence of the Cross-Relaxation on ESA-Process in Tm3+ Doped Fluorophosphate Glass

Abstract

Spectral properties of UV and blue upconversion fluorescences in Tm3+ doped fluorophosphate glass with use of a tunable DCM dye laser for single wavelength pumping were studied at room temperature. Two emission bands centered at 363, 451 nm from the 1D2 level and one emission band centered at 478 nm from the 1G4 level were observed. Two photon absorption mechanisms responsible for these fluorescences was confirmed by quadratic dependence of fluorescence intensities on the incident pumping intensity. Excitation spectra and decay profiles of the same fluorescences also proved that the mechanism leading to these emissions was the excited state absorption (ESA) originating from the 3F4 and the 3H4 levels to the 1D2 and the 1G4 levels, respectively.