The dynamic processes of the Er3+ ion's populations of ErP5O14 crystal excited by 650nm laser

Rate equations describing the dynamic processes in Er 3+ doped pentaphosphate crystals were built up. Using this rate equations the dynamic processes of the building up processes of the populations of the states of Er 3+ ions in ErP 5 O 14 crystal was gotten. The spontaneous radiative processes, multiphonon nonradiative processes, absorption of the pump photons and the possible energy transfer processes between all states of Er 3+ ions were included in the rate equations, and the pump power was supposed to be unchanged with time. Considered that the equation n(t 0 +(Delta) t)=n(t 0 +dndivided bydt(Delta) t would be held if (Delta) t was small enough, and using the initial condition n 1 =1.0, n i =0(idoes not equal1), the time dependent populations of all states could be gotten from the rate equations. When the pump power was 10 3 W, population of the ground state decreased rapidly with time and then tended to stable, at the same time, the population of 4 F 9/2 , the state excited directly by the pump light, formed a peak-like structure and then tended to stable. The gradient of the decay side and the rising side of this structure was close, which believed to be the result of the large number of the energy transfer processes between 4 F 9/2 and other states and the great rate of these processes. Populations of the other excited states lower than 4 F 9/2 were all increase at first and then decrease with time while excited states higher than 4 F 9/2 were all increase with time and then tended to be stable. The system came to be stable at about 140 microsecond(s) .