Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability

Upconversion luminescence (UCL) properties from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses excited by a 980 nm laser diode are investigated. The ln–ln plots of the UCL intensity versus laser power show abnormal relations: the slopes are larger than those reported in other papers. When tuning the laser power up and down successively, intrinsic optical bistability of Yb3+ ions is observed at room temperature in the visible and infrared range without external cavity. And this nonlinear effect induces the abnormal UCL phenomena.