Polarization properties and frequency stabilization of an internal mirror He-Ne laser emitting at 543.5 nm wavelength

Frequency stabilization to the gain profile of an internal mirror He–Ne laser emitting at 543.5 nm wavelength is described. The dependence of the power and polarization on frequency was investigated for multi-mode and two-mode operation. The emitted laser modes are linearly polarized. Two orthogonal eigenpolarizations fixed to the laser tube were observed. Spontaneous switching between these polarizations occurred when the laser frequency was scanning through the gain profile. In two-mode operation, these polarization flips have been suppressed by applying a weak magnetic field transversal to the gas discharge. Under such operation conditions the frequencies of the laser could be stabilized to the gain profile by controlling the power difference of the two modes to zero. The fractional frequency reproducibility is in the region of f/f3×10^–8.