Competition of modes having different Q factors in a gas laser with a uniformly broadened line

The effect of two longitudinal, orthogonally polarized, competing modes in a He-Ne laser having a uniformly broadened line is investigated in the case when the modes are characterized by different Q factors. It is shown that if the Q factors of the modes become different, the frequency range of stable mode generation does not change, but shifts away from the symmetrical position with respect to the center of the lasing line. The magnitude of the shift is determined experimentally as a function of the laser parameters. The possibility of using a two-mode laser with spatial mode separation for measuring low optical densities is examined.