Stabilizing carrier-envelope offset frequency of a femtosecond laser using heterodyne interferometry

We propose a time-domain f_ceo stabilization method of a femtosecond laser using heterodyne interferometry. A femtosecond pulse train that is delayed by a spatial delay line interferes with the original pulse train. The phase difference between heterodyne interference signals extracted from different spectral regions is used to stabilize the relative position of the two pulse trains; then the heterodyne interference phase is used to stabilize the carrier-envelope offset frequency f_ceo. The experimental results show that, after being stabilized, the relative Allan deviations of f_ceo are 1.0×10^-9 at 0.5 s and 4.6×10^-10 at 50 s.