LUMINESCENCE PROCESSES IN TM3-ION-ACTIVATED AND ER3+-ION-ACTIVATED, YB3+-ION-SENSITIZED INFRARED UP-CONVERSION DEVICES()

Frequency upconversion characteristics in Er3+- or Tm3+-ion-activated and Yb3+-ion-sensitized luminescent materials have been investigated. The principal goal was to obtain high-brightness, blue and green light sources under 980 nm emitting laser diode light excitation. Processes leading to the efficient upconversion have been investigated both by experimental and analytical methods. It has been shown that upconversi on efficiencies are principally determined with Yb3+ ion excited state lifetime, which is highly influenced by device optical confinement as well as material characteristics. The effect of the optical confineme nt has been analyzed quantitatively on the basis of a rate equation mo del. Criteria for realizing efficient infrared upconversion devices ha ve been presented. A strong tendency toward temperature quenching has been observed especially in blue emitting materials. This temperature dependence has been shown to be principally due to increase of nonradi ative decay in the Yb3+ ion excited state.