Ultra-Fast Decay Process of Electrons in LiNbO₃ Crystal Induced by Femtosecond Pulse

Temporal evolution of absorption induced by single femtosecond pulse (130fs, 800nm) with high intensity in LiNbO₃ is obtained using the probe shadow imaging technique in order to investigate light-induced electron relaxation processes. By saturating the polaron density with a high intensity laser pulse, ultra-fast decay process on picosecond time scale is observed. The decay time constant is about 141ps and it is attributed to the direct interband electron--hole recombination process.