7C7 - Infrared quantum counter action in rare earth doped fluoride lattices

This paper reviews the results of a program of experimental work on infrared quantum counter action in trivalent rare earth doped CaF
2
, SrF
2
, BaF
2
, and LaF
3
lattices. The action has been found in eight of the nine possible ions that could give an output in the visible region. While the strengths of the various schemes at a 1 percent doping level are consistant with a low concentration theory, the strengths of the schemes at a 10 percent doping level indicate that there are ion-ion interactions influencing the systems. These ion-ion couplings are so effective that three photon addition schemes have been identified.