All-optical, Three-axis Fiber Laser Magnetometer

: This report describes the development of an undersea fiber-optic magnetometer, suitable for remote deployment as a moving target detection system. A comprehensive overview of the operating principle and performance of this sensor system is given. The magnetic field sensor utilizes the Lorentzian force acting on a current carrying bridge in the presence of a magnetic field, which drives its oscillation measured with a fiber laser strain sensor. The undersea node occupies a footprint of 303 mm x 303 mm and is connected to the opto-electronics unit through an undersea cable 1 km in length. The deployed orientation of the node is measured with an integrated MEMS inclinometer, which is optically powered. The sensor is capable of achieving a magnetic field resolution of 343 pT/Hz(1/2) at 1 Hz for 75 mA (rms) dither current when operated in a moderate vacuum of 1 kPa.