Abstract
Free-carrier absorption was observed in intrinsic crystals of strontium titanate when excited by two-photon absorption of laser pulses. The temperature dependence of the recombination time was found to be exponential, with an activation energy of 0.105 eV. This energy may correspond to the depth of the valleys at the edges of the Brillouin zone in the lowest conduction band or to the activation energy of localized traps.