Effect of intracavity back reflections on the accuracyand stability of optical frequency standards

The shifts of centres of nonlinear absorption and dispersion resonances in lasers with an internal absorbing cell are described. The shifts are caused by parasitic reflection of light from an intracavity plate and oscillate depending on the plate position. It is shown that this reflection leads to losses oscillating depending on the plate position. The main reasons of shifts in this case are frequency modulation used for laser frequency stabilisation and the curvature of the gain line in the two-mode regime. The results of a model experiment agree with theoretical estimates.