Modification of stretched-exponentially dependent depopulation dynamics of small polaron in Fe:LiNbO₃ crystals

An improved stretched-exponential model for the analysis of the relaxation of small polarons in iron doped LiNbO₃ at high pump light intensities was discussed. It was found that depopulation of the small polarons in Fe:LiNbO₃ crystal was characterized by electron exchange between small polarons and Fe₊₃ ions and short-range energy interaction between small polarons and antisite defects. It is observed that short-range energy-transfer process plays a much weak role in the depopulation of the small polarons and is only effective during the first 100 μs. The results show that electron transition process mainly determines the relaxation dynamics behavior of the small polarons.