Fiber Bragg Grating Laser Magnetometer

Fiber lasers formed with rare earth doped fiber and fiber grating reflectors are being developed as tunable single frequency devices for a number of communications applications [1]. These devices can also be used as sensors, and can be multiplexed using the inherent wavelength encoded nature of their output. Recently we demonstrated that an exceptionally high sensitivity to cavity strain can be realized using an interferometric readout technique to monitor the wavelength shift of fiber Bragg grating lasers (FBGL) [2], This technique allows the strain-induced wavelength shift in a FBGL to be monitored to within a resolution of better than 1 part in 1014 for a 1 Hz measurement bandwidth in the frequency range above ~3 kHz. This wavelength resolution corresponds to an optical frequency resolution of ~1 to 10 ηζ/√ηζ, and consequently provides a high sensitivity to any perturbation induced via a suitable transduction mechanism designed to transpose the measurand field into FBGL cavity strain.