Polarization competition in a quasi-isotropic CO2 laser

We experimentally study the polarization dynamics of a single-mode CO2 lase r during the switch-on transient of the laser intensity. We find a strong c ompetition between two linearly polarized fields, which finally collapse in to a single field. As a result of this competition, the two coexisting fiel ds oscillate out of phase by rr rad for time intervals much longer than tha t of the relaxation oscillation. One can control the oscillation frequency of the two polarized fields by varying the intracavity anisotropies. This p henomenon is interpreted in the framework of Maxwell-Bloch equations by add ition of nonlinear terms to the polarization equations that allow the field s to compete while they interact with the same population inversion. (C) 20 01 Optical Society of America.