Concentration dependence of up-conversion quenching rate in Er-doped glass fiber

For creation of planar and fiber amplifiers, the up-conversion processes in Er-doped glasses should be taken into account. We consider the up-conversion transition in a pair of Er/sup 3+/ions, when in initial state both the ions are at the /sup 4/I/sub 13/2/level, and in final state one ion is at the /sup 4/I/sub 15/2/ ground level and other at the /sup 4/I/sub 9/2/ level.