Polarization states and dynamics of the lowest order transverse modes in a Fabry-Perot CO2 laser

We characterize the polarization properties of the lowest order transverse patterns in a CO2 Fabry-Perot laser designed anisotropies in both the loss and detuning for different states of polarization. Emission with an annular intensity pattern for a single CO2 line is found to come from the superposition of two Gauss-Hermite modes with linear polarizations perpendicular to their nodal lines. The nodal lines of these modes are not perpendicular and the modes have slightly different frequencies.