High-resolution fiber-optic low-frequency voltage sensor based on the electrostrictive effect

A minimum detectable voltage of 40 nV/ square root Hz at 1 Hz is demonstrated in a fiber-optic interferometric low-frequency voltage sensor. The device maintains good resolution below 1 Hz, providing a minimum detectable voltage of 55 nV/ square root Hz at 0.1 Hz and 129 nV/ square root Hz at 0.03 Hz. High resolution at low frequencies is attainable due to the nonlinear strain response of the electrostrictive transducer under an applied electric field, which upconverts low-frequency voltage signals as sidebands of a high-frequency carrier where 1/f noise is not dominant. The measured low-frequency data represent an improvement of >45 dB over previously reported results.<
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