Rb D \(_2\) -Line Polarization Spectroscopy for Laser Frequency Locking

We experimentally generate Doppler-free Rb D \(_{2}\) line spectra by using saturated absorption spectroscopy (SAS) and polarization spectroscopy. Using a full multi-level (including all the magnetic Zeeman sub-levels) rate equation model, we calculate the effect of several parameters such as pump power, pump-probe polarization configuration and beam diameter on the error signals thus produced for laser frequency locking, corresponding to the hyperfine transitions \(F_g=2\rightarrow F_e=1,2,3\) of \(^{87}\) Rb. The closed hyperfine transition, \(F_g=2\rightarrow F_e=3\) is found to provide the strongest error signal due to its large oscillator strength ( \(\sim 0.7\) ) as compared to the other two open hyperfine transitions.