Influence of Mg doping on the behaviour of polaronic light‐induced absorption in LiNbO₃

Abstract Transient light‐induced absorption changes α_li(t), caused by optically generated small polarons, are investigated in LiNbO₃:Mg below and above the optical‐damage‐resistance threshold (ODRT). The lifetime of α_li(t) is reduced by three orders of magnitude above the ODRT while a significantly enhanced amplitude $ \alpha ^{\rm max} _{\rm li} $ is observed in the infrared. Our observations are in full accordance with the predictions of microscopic models for the ODRT, namely the removal of Nb_Li antisite defects upon incorporation of Mg ions, and an enhanced dark conductivity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)