Pulse Velocity and Mode Pulling in a Laser with Equally Spaced Modes

Abstract

Mode pulling and pulse velocity in an inhomogeneously broadened laser are examined starting from the assumption that the steady‐state dispersion of the gain medium results in equally spaced modes. By summing the mode E‐fields in the cavity it is found that the pulse velocity is less than that of light and equal to the classical group velocity dω/dk. The pulse shape is stable with time even in the presence of dispersion. The ratio of the intermode beat frequency to that of the empty cavity equals the ratio of the pulse velocity to that of light. Previous measurements on the He–He self‐locked laser support these results.