Optical gain in Er3+-doped transparent LuVO4 crystal at 850Â nm

Evidence of a positive optical gain has been observed in an Er3+-doped LuVO4 crystal in a pump and probe experiment. The radiative transition from the 4S3/2(2H11/2) level to the 4I13/2 metastable level of the Er3+ ion gives rise to an intense emission centred at 850 nm. The 4S3/2(2H11/2) level of Er3+ ions is populated with high power laser pulses at 532 nm due to the 4I15/2 → 4S3/2(2H11/2) ground state absorption. The 4S3/2(2H11/2) → 4I13/2 electronic transition is stimulated with a low signal cw beam at 850 nm. Under these conditions, the high power pump pulses allowed to reach the population inversion necessary between the Er3+ levels of the transition 4S3/2(2H11/2) → 4I13/2. An increase of the emission intensity of the sample is observed at the signal wavelength, due to the stimulated emission. Positive optical gain around 2 cm−1 (8.6 dB/cm) has been measured in Er3+-doped LuVO4 crystal.