Investigation and Optimization of Sub-Doppler DAVLL Error Signal for ECDL Stabilization

Sub-doppler dichroic atomic vapor laser lock (davll) is a modulation-free laser stabilization method that combines davll and saturated absorption spectroscopy (sas). the performance of this highly sensitive stabilization technique strongly depends on the characteristics of the generated error signal. the slope of the error signal determines the lock sensitivity or how fast the frequency compensation could be made in the feedback loop, and the amplitude of the error signal determines the lock stability or how much noise the feedback loop can tolerate before laser unlocking. we have analytically modeled the error signal of the sub-doppler davll considering all possible transitions between zeeman sublevels and compared it with the experimental results. using the analytical and experimental results, it is shown that the values of the required magnetic fields for maximizing the slope and amplitude of the error signal are close to each other. selecting the mentioned values of the magnetic field for optimization of the sub-doppler davll error signal is highly useful for sensitive and stable laser locking.