Modulation-free pump-probe spectroscopy of strontium atoms

We have performed polarization spectroscopy and sub-Doppler DAVLL on the (5s5s) 1^S_0 -> (5s5p) 1^P_1 transition of atomic strontium. Both techniques generated a dispersion-type lineshape suitable for laser stabilization, without the need for frequency modulation. In both cases the signal is generated primarily by saturation effects, rather than optical pumping. The dependence of the amplitude and gradient on intensity and magnetic field were also investigated.