Fig. 1. (a) Experimental setup for magneto-optical detection; (b) timing sequence of the experiment. Cooling time tc and the repumping time tr are 177.5 and 179 ms, respectively. Probe time tp is 7.5 ms which is switched on immediately after the cooling light is turned off.

Fig. 2. Transmitted probe light intensity when the biased magnetic field is 20.6 and 0 mG (solid and dashed lines, respectively). There is repumping light leakage at B=0; pure transmitted probe light intensity is obtained by subtracting such repumping light leakage.

Fig. 3. Rotation angle versus the biased magnetic fields at different incident probe powers where the uncertainty of the data points is 5%. Probe light transition is from 5 S1/22,F=2 to 5 P3/22,F′=2. Magnetic field is from 0 to 34.2 mG. Incident probe intensities are 0.43, 1.39, 2.19, and 2.46  mW/cm2. Largest rotation angle is 0.046 mrad when the magnetic field is 20.6 mG and the probe light intensity is 0.43  mW/cm2.

Fig. 4. Rotation angle versus the probe light intensity where the uncertainty of the data points is 5% at different detunings 0, −3.9, and, −6.3 MHz, respectively. Probe light transition is from 5 S1/22,F=2 to 5 P3/22,F′=2, and the magnetic field is set as 20.6 mG. Profiles are similar as for different probe detunings; there is a peak at about 0.31  mW/cm2 and then decreases slowly.

Fig. 5. Rotation angle versus probe light detuning where the uncertainty of the data points is 5%. Probe light transition is from 5 S1/22,F=2 to 5 P3/22,F′=2. Magnetic field is 20.6 mG and the incident power is 0.31  mW/cm2. Maximum rotation angle of 0.087 mrad is at red detuning −3.9  MHz.