YAG and sapphire crystals were irradiated by 800 nm and 120 fs laser pulses. Crystals changed to dark and absorption increased after irradiation. Irradiation induced cracks were found in SEM photograph of CZ grown sapphire. After annealing at 500degreesC for an hour, absorption of YAG decreased and absorption of sapphire increased. Darkness of YAG crystal was attributed to formation of color centers, and the darkness of sapphire was caused by irradiation-induced micro-cracks. Irradiation resistance of YAG is better than sapphire according to micrograph and absorption spectrum. (C) 2003 Elsevier B.V. All rights reserved.