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 CaF2, SrF2, BaF2, and LaF3lattices. 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.