Stabilization of the frequency of a highly coherent injection laser using intra-Doppler saturated absorption resonances

Two injection lasers with an external resonator were stabilized using intra-Doppler resonances of saturated absorption at the D₂ line of cesium. The stability of the frequency of injection lasers was determined for the first time using fluctuations of the frequency representing the difference between two independently stabilized lasers and it reached (1.4–4) X 10^– 11 for times in the interval 0.1–10 s.