Investigation of an Не–Ne/I$_2^{129}$ ring laser stabilized utilizing saturated absorption resonances at the 623 nm wavelength

Theoretical and experimental investigations were made of an He–Ne ring laser ($\lambda=633$ nm) with an iodine intracavity absorption cell. It was shown that the absorption saturation effect is a decisive factor in the formation of absorption phase resonances, whilst saturation of the dispersion results in asymmetry of the phase resonances when the center of the profile of the gain phase resonance does not coincide with the center of the absorption profile. It was confirmed experimentally that the contrast of the absorption phase resonances depends weakly on the laser parameters. Investigations were made of the frequency shift of the stabilized laser radiation and the stability of the radiation frequency was measured and found to be $\sim2\cdot10^{-12}$ for an averaging time of 100 s.