Abstract
A fiber-optic magnetic-field sensor is constructed by bonding a single-mode fiber to a nickel cylinder. The magnetic field, by means of the magnetostrictive effect, alters the state of polarization of light in the fiber. A sensitivity of 1.76 × 10−2 rad/m Oe is demonstrated, permitting detection of fields as small as 4.4 × 10−6 Oe/m of fiber.