The processes of optical dissociation and recombination of bipo-larons 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 (l = 532 nm) are performed and the lifetime of small free polarons is determined in undoped LiNbO<sub>3</sub> 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.

© 2005 Optical Society of America

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