Sensitivity enhancement of a dead-zone free all-optical 4He atomic magnetometer based on a liquid-crystal polarization rotator

Abstract

We report our recent progress in the experimental implementing of an all-optical 4He atomic magnetometer being free from the dead-zone effect. A liquid crystal is adopted to constitute a polarization rotator. The light linear polarization vector can be adjusted and ultimately kept perpendicular with respect to the varying ambient magnetic field direction. We then make some further investigations to enhance the magnetometer sensitivity through reducing the laser intensity noise and optimizing parameters like the laser beam size, the input laser power and the modulation depth. The magnetometer demonstrates an improved magnetic field sensitivity of about 300 fT/Hz1/2 for frequencies above 10 Hz.