Magnetic-field enhanced modulation transfer spectroscopy: theory and experiment

We report a theoretical and experimental study on magnetic-field enhanced modulation transfer spectroscopy (MTS) for the 5S_1/2 (F = 1)→5P_3/2 (F′ = 0, 1, and 2) transitions of ⁸⁷Rb atoms. The density matrix equations are solved numerically to obtain the MTS spectra and an excellent agreement is found between the experimental and calculated results. In particular, the enhancement of the MTS signal for the F = 1→F′ = 0 transition in the presence of the magnetic field is directly verified based on the comparison of the results calculated by neglecting with those calculated including the Zeeman coherences in the F = 1 ground state. The unexpected behaviors of the F = 1→F′ = 1 transition are also examined with two different configurations of probe-pump beam polarization.