A tunable Doppler-free dichroic lock for laser frequency stabilization

摘要

We propose and demonstrate a laser frequency stabilization scheme whichgenerates a dispersion-like tunable Doppler-free dichroic lock (TDFDL) signal.This signal offers a wide tuning range for lock point (i.e. zero-crossing)without compromising on the slope of the locking signal. The method involvesmeasurement of magnetically induced dichroism in an atomic vapour for a weakprobe laser beam in presence of a counter propagating strong pump laser beam. Asimple model is presented to explain the basic principles of this method togenerate the TDFDL signal. The spectral shift in the locking signal is achievedby tuning the frequency of the pump beam. The TDFDL signal is shown to beuseful for locking the frequency of a cooling laser used for magneto-optcaltrap (MOT) for $^{87}Rb$ atoms.