Optical bistability in Yb3+:YCa4O(BO3)3 crystal

Abstract A hysteresis cycle has been observed in 15 mol.% Yb 3+ :YCa 4 O(BO 3 ) 3 by varying infrared excitation power while recording Yb 3+ cooperative luminescence. The sample was mounted in a cryostat maintained at 12.5 K. Two mechanisms have been considered to explain this optical bistability: Yb 3+ pair interaction and effects of heating by the laser excitation. The former process, which should involve a large transition displacement, has not been identified. On the other hand, a monitoring of the sample temperature by Yb 3+ infrared emission showed that thermal effects cannot be neglected. However, a simple model of thermal equilibrium is unable to reproduce the hysteresis. This suggests that other processes should be taken into account, like temperature-dependent energy transfer towards traps.