Multiplexed Low-Frequency Electric and Magnetic Field Fiber Optic Sensors

A frequency-multiplexed fiber optic interferometric sensor designed for the simultaneous measurement of low-frequency electric and magnetic fields is demonstrated. The sensor relies on the nonlinear transduction mechanism in electrostrictive and magnetostrictive materials for frequency-division multiplexing in a single interferometer with one unmodulated laser. The sensor exhibits extremely low cross talk (< −75 dB) between channels. Effects resulting from the nonlinear response of the fiber optic interferometer are discussed with regard to sensor multiplexing. Finally, low-frequency electromagnetic signals from remotely located electric and magnetic dipoles are detected with the fiber optic sensor.