Broadening of the spectrum of a giant ruby laser pulse in molecular iodine vapor

An experimental investigation was made of the behavior of a ruby laser pulse transmitted by a resonantly absorbing medium of molecular iodine vapor. When the radiation power density was I > 80 MW/cm² and the iodine vapor pressure exceeded 60 mm Hg, the spectrum of the pulse at the exit from an iodine cell was 1.4 times wider than the spectrum at the entry to the cell. A possible explanation of the broadening is considered.