We have observed persistent spectral hole burning (PSHB) in Eu3+ -doped sodium borate glasses irradiated with near-IR femtosecond laser pulses. As-prepared glasses, i.e., glasses melted in air, do not show PSHB even at low temperatures (similar to 77 K), but room-temperature PSHB occurs in the irradiated glasses. The exposure to IR radiation causes both the reduction of Eu3+ to Eu2+ and the formation of intrinsic defects. We propose that the photoinduced redistribution of electric charges between Eu3+ to Eu2+ is responsible for the occurrence of PSHB. (C) 2001 Optical Society of America.