FIBEROPTIC AC ELECTRIC-FIELD SENSOR BASED ON THE ELECTROSTRICTIVE EFFECT

We report a fiber-optic ac electric-field sensor based on the electrostrictive effect. The dc-biased electrostrictive transducer-lead magnesium niobate-based ferroelectric relaxor-displays an electric-field resolution of 7 (mu-V/m)/square-root Hz with a corresponding voltage resolution of 1 nV/square-root Hz for 15 cm of fiber. Such high resolution is possible in nonlinear transducers owing to the dependence of the ac strain on applied dc bias. Conversely, the ac strain in linear piezoelectric transducers does not vary with the dc field, and the ultimate resolution obtained with such devices is dependent only on the piezoelectric constant and the total fiber length.