Simple optical-fiber weak-field magnetometer based on a homodyne Mach–Zehnder interferometer

The possibility of using a few-mode optical fiber to measure weak magnetic fields (~ 10^–6 Oe) has been studied. A highly sensitive magnetometer has been designed on the base of an optical-fiber sensor and a homodyne Mach–Zehnder interferometer. Methods of homodyne interferometry can be used successfully for reliable stabilization of the pattern of interference fringes in an interferometer based on a few-mode fiber. The frequency and amplitude characteristics of an optical-fiber device for measuring weak magnetic fields, 10^–1–10^–6 Oe, in the frequency range 30–500 Hz have been studied.