THE NONRADIATIVE ENERGY-TRANSFER IN HIGH ACCEPTOR CONCENTRATION CODOPED ND,HO-YAG AND ND,ER-YAG

For three luminescent laser crystals it is found that the dipole-dipol e interaction between donor-acceptor pairs at short distances is domin ated by higher order multipolar interactions. This effect is reflected as a fast initial decay in the donor emission transient of the codope d systems Nd,Ho:YAG and Nd,Er:YAG at high acceptor concentrations. The effect is enhanced as the acceptor concentration is increased. At lon g times the donor emission transients show the effects of the dipole-d ipole interaction between donor-acceptor pairs, that is, the long rang e multipolar interaction drives the non-radiative energy transfer. The Monte Carlo model shows these effects for the non-radiative energy tr ansfer process applied to those luminescent systems. For this model th e discreteness of the YAG lattice is kept since dopants are randomly p laced into the 24c sites. The donor emission transients are obtained b y calculating the probabilities of the events that occur after a donor is excited.