Polarized radiation from a single-mode CO2 laser with internal mirrors

Linearly polarized radiation was generated in a single-mode CO₂ laser without any polarizing elements. The degree of the polarization was a function of the radiation power, while its direction was determined by the orientation of the mirrors and could flip to the orthogonal polarization when the mode and spectral characteristics changed. The effects observed were explained by an amplitude anisotropy of the active medium and of the resonator mirrors.