ROOM-TEMPERATURE PHOTON AVALANCHE UP-CONVERSION IN ER-DOPED FLUORIDE GLASS AND FIBER PUMPED AT 700 NM

A strong emission at 550 nm as well as a series of other wavelengths h ave been observed in Er-doped ZrF4-BaF2-LaF3-AlF3-NaF fibres and bulk glass at room temperature when the excitation wavelength is about 700 nm, which is far away from the absorptions from the ground state of Er 3+ ions. Measurements of excitation, time delay and intensity dependen ce versus pump power suggest that these emissions are caused by the ph oton avalanche effect originating from the multiphonon side-band absor ption. The excitation mechanisms of this photon avalanche have been an alysed. Spectral measurement also show some strong emissions in the IR region, some features of which are probably linked with laser action.