Optical properties of rare earth doped oxyfluoride glass-ceramics
|Fernando Lahoz , Inocencio R. Martín , Víctor Lavín , Ulises Rodríguez , José M. Cáceres , Fernando Rivera , Javier Plata , Sara González-Pérez|
Universidad La Laguna, La Laguna 38206, Spain
Oxyfluoride glass-ceramics are obtained when a precise thermal treatment is applied to a precursor glass. This thermal treatment causes that fluoride nanocrystals precipitate in the vitreous matrix. X-ray diffraction measurements have been performed and reveal that two phases coexist in the glass-ceramic. One is vitreous and has an oxyfluoride composition and the second one is crystalline and provides a fluoride environment. In fact, the macroscopic properties of the glass-ceramic are characteristic of the aluminosilicate glassy phase except the optical properties of the rare-earth (RE) ions, which are characteristic of low-phonon energy fluoride crystals. The fluoride nanocrystals have low-phonon energy and, as a consequence, the probability of nonradiative relaxation processes is expected to be low, giving place to longer excited state lifetimes than in the oxyfluoride precursor glass. A very efficient IR to visible upconversion process is reported in Ho3+ doped glass-ceramics. Three strong emission bands in the primary color components, red, green, and blue give place to an intense white emission light, which is observed by the naked eye under IR excitation at 750nm. The excitation mechanism of this efficient upconversion emission is studied and it was found to be due to a photon avalanche process.
Finally, laser action in Nd3+ doped gass-ceramics has been studied. A relatively low pump threshold of about 18 mJ was detected. Losses due to UV and visible upconverted emission inside the laser cavity have been observed.
Presentation: oral at E-MRS Fall Meeting 2005, Laser Ceramic Symposium, by Fernando Lahoz
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-20 15:08 Revised: 2009-06-07 00:44