Nonlinear cooperative energy transfer in La/sub 1-x/Ce/sub x/F/sub 3/ crystals

Summary form only given. We report on a new nonlinear optical phenomenon in LaCeF/sub 3/:Nd crystals of cooperative energy transfer-cooperative cross-relaxation, that is the energy transfer from single donor ion simultaneously to the pair (or more) ions, acting as nonlinear cooperative acceptor. The dependence of fluorescence intensity and decay rate at the kinetic stage of the process here can not be described by linear dependence on acceptor´s concentration and becomes essentially nonlinear.