New lock point offset correction-based frequency stabilization method for longitudinal Zeeman laser

In order to study the lock point offset in the longitudinal Zeeman-stabilized laser, we establish the mathematic model for the offset between the lock point and the power-balanced point of the two oppositely circularly polarized beams out-putted from the longitudinal Zeeman laser, and propose a new frequency stabilization method based on the lock point offset correction. In the proposed method, the random elements of the lock point offset are greatly suppressed by dividing the two circularly polarized beams efficiently and detecting the beam power precisely, while the relatively stable elements are compensated in real-time, and the beam frequency is effectively stabilized. Experiments show that, for the longitudinal Zeeman-stabilized laser based on lock point offset correction, the peak-to-peak range of the beam frequency is 2 MHz (4 × 10^-9) during 2.4 hours, and the average beam frequency drifts by less than 0.6 MHz (1.3 × 10^-9) in 24 hours, and the root Allan variance is 1.9 × 10^-10 (sample time 1000 s). It comes to the conclusion that the proposed method can depress beam frequency drift of the longitudinal Zeeman-stabilized laser.