Cs magnetometers optically pumped with radiation of diode lasers

Atomic magnetometers optically pumped with resonance lamps have been explored and used in applications for more than 40 years. After many improvements these devices have reached high level of performance and fundamental limits make further progress difficult. Development of reliable single mode diode lasers (DL) that can be tuned to D lines of alkali atoms opened new possibilities such as increasing sensitivity of magnetic field measurements in multilayer shield with applications in encephalography and cardiography or dramatic decrease of the volume and power consumption in chip scale atomic magnetometers. This paper investigates Cs M_x magnetometer and gradiometer that operate in terrestrial magnetic field. Circularly polarized radiation of extended cavity DLs and/or short cavity edge-emitting DLs has been used for optical pumping. Efficiencies of optical pumping at all hyperfine (HF) transitions of D₁ and D₂ lines have been measured and compared. For cells with buffer gas pressure less than 30 Torr and for the antirelaxation coated (ARC) cells all 4 HF components of the D₁ line can be excited separately while for D₂ the simultaneous pumping occurs via three HF sublevels of the 6P_3/2. The efficiencies of laser pumping are compared with lamp pumping. The basic advantage of the laser pumping is a possibility to tune laser line to the center of absorption line for maximum efficiency or to make a proper offset to provide minimum of the noise and/or of the optical shift. For applications in cardiomagnetometry the required spatial resolution can be provided by using multichannel gradiometer.