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Updated: Jul 8, 2026

Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
Balanced heterodyne signal extraction in a postmodulated Sagnac interferometer at low frequency
Abstract:
We describe a balanced-heterodyne postmodulated Sagnac interferometer signal extraction method that is suitable for gravitational wave detection. The method is simple to implement by placement of a polarization-selective modulator after the beam splitter in the dark port of the interferometer. The postmodulated Sagnac interferometer retains its common path advantage and exhibits insensitivity to laser frequency noise below, at, and above the heterodyne frequency. Balanced detection reduces sensitivity to laser amplitude noise. In this scheme mirror displacement signals were rf demodulated and observed from 0.2 to 10kHz.
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