Femtotesla atomic magnetometry in a microfabricated vapor cell

We describe an optically pumped Rb-87 magnetometer with 5 fT/Hz(1/2) sensitivity when operated in the spin-exchange relaxation free (SERF) regime. The magnetometer uses a microfabricated vapor cell consisting of a cavity etched in a 1 mm thick silicon wafer with anodically bonded Pyrex windows. The measurement volume of the magnetometer is 1 mm(3), defined by the overlap region of a circularly polarized pump laser and a linearly polarized probe laser, both operated near 795 nm. Sensitivity limitations unique to the use of microfabricated cells are discussed. (C)2010 Optical Society of America