We present an experimental and theoretical investigation of the coherent population trapping (CPT) resonance excited on the D1 line of 87 Rb atoms by bichromatic linearly polarized laser light. The experimental results show that a lin‖lin transition scheme is a promising alternative to the conventional circular-circular transition scheme for an atomic magnetometer. Compared with the circular light transition scheme, linear light accounts for high-contrast transmission resonances, which makes this excitation scheme promising for high-sensitivity magnetometers. We also use linear light and circular light to detect changes of a standard magnetic field, separately.

We demonstrate experimentally an atomic magnetometer based on optical pumping theory, a magnetic resonance that is induced by a radio frequency field and dependent on the magnetic field strength. Compared with the conventional method using one radiation field, which is used not only as the probe beam but also as a pump beam, the additional re-pump beam can increase remarkably the amplitude of the signal. It is shown that the amplitude of the magnetic field resonance signal can increase more than 55% by using an additional re-pump beam, which makes the sensitivity of the magnetometer higher. Finally, we investigate the relation between amplitude of the signal and re-pump laser power, and calculate the atomic population in the trapping states with rate equations.