Two-beam nonlinear Kerr effect to stabilize laser frequency with   sub-Doppler resolution
  Avoiding laser frequency drifts is a key issue in many atomic physics experiments. Several techniques have been developed to lock the laser frequency using sub-Doppler dispersive atomic lineshapes as error signals in a feedback loop. We propose here a two-beam technique that uses non-linear properties of an atomic vapor around sharp resonances to produce sub-Doppler dispersive-like lineshapes that can be used as error signals. Our simple and robust technique has the advantage of not needing either modulation or magnetic fields. 
Weliton Soares Martins, Hugo L. D. de S. Cavalcante, Thierry Passerat   de Silans, Marcos Ori\'a, Martine. Chevrollier
physics.atom-ph physics.optics