Hysteretic behaviour in the fluorescence of Yb3+ in LiNbO3:MgO crystals

Hysteretic behaviour in the luminescence of Yb3+ ions in LiNbO3:MgO crystals at low temperatures is observed as a function of the excitation power inside the 2F7/2(0)→2F5/2(1) transition of Yb3+ ions. The results are tentatively explained in terms of the laser heating effect on the thermal distribution between the crystal field levels of the 2F5/2 excited state which varies along the hysteresis loop. This fact would be responsible for the nonlinear population change needed for the observation of bistability.