ENERGY-TRANSFER IN YB3+ER3+YLF

Yb3+ as codopant in Er3+ doped laser hosts is interesting due to the b road absorption band and the high absorption cross-section around 940 nm wavelength in Yb3+. We report on measurements to determine the cros s-relaxation parameter W-1b for the energy transfer from excited Yb3to ground-state Er3+ and W-a3 for the inverse process in LiYF4 (YLF). The micro-parameters, describing the electric dipole-dipole interactio n between a donor and an acceptor ion are determined for the normal an d the inverse process. Furthermore, the micro-parameters for the energ y migration between the Yb3+-ions and between the Er3+-ions are determ ined. (C) 1997 Elsevier Science B.V.