Lifetime of small polarons in nominally pure, reduced LiNbO_3

摘要

The processes of optical dissociation and recombination of bipolarons are investigated in congruently melting lithium niobate. Time-resolved and temperature-dependent measurements of the light-induced absorption in the blue, red and infrared spectral range after exposure to short, intense laser pulses (λ =532 nm) are performed and the lifetime of small free polarons is determined in undoped LiNbO_3 at room temperature for the first time. A qualitative charge-transport model for dissociation of bipolarons and recombination of small polarons is developed on the basis of our findings.