PHOTON AVALANCHE LUMINESCENCE OF ER3+ IONS IN LIYF(4) CRYSTAL

Photon avalanche effect has been found in Er3+:LiYF4 crystal at room temperature when pumped at two wavelengths regions, 579 and 690 nm. These two pump schemes correspond to excitations energies from the ground state falling between S-4(3/2) and F-4(9/2), and between F-4(9/2) and I-4(9/2) levels, respectively. Spectra and excited state dynamics of these nonlinear processes have been investigated. The link between the photon avalanche initial step and multiphonon side band absorption has been explored. Results show that the initial absorption region comes essentially from the anti-Stokes multiphonon contribution. The role of an independent injection of population into the metastable level is also investigated showing that the system may behave as a conditionally stable positive feed-back system. Temperature dependant measurements have shown that, a higher temperature is favorable for the avalanche emission in this system, which is different from other ion and crystals systems having displayed an avalanche effect to date.