Looping mechanism in Er-doped fluoroindogallate glasses

In this work we report a room temperature green upconversion in Er-doped fl uoroindogallate glasses, pumped at 833 nm. The rise time and stationary int ensity of the S-4(3/2)+H-2(11/2)-->I-4(15/2) Er3+ transition as a function of laser intensity were monitored. Some possible pumping mechanisms are dis cussed in detail, and it is concluded that the main pumping route may be de scribed in terms of the looping mechanism. It is also shown that cross rela xation among neighboring pairs of Er3+ ions is near the threshold value to achieve the photon avalanche region. (C) 2000 American Institute of Physics . [S0021-8979(00)02212-X].