title: Polarization-based balanced heterodyne detection method in a Sagnac interferometer for precision phase measurement.
abstract: We describe a balanced heterodyne detection method for a Sagnac interferometer that uses a polarization-dependent beam splitter. The signal and the local oscillator are orthogonally polarized components of a single laser beam, permitting the detection of the signal by subtraction of two photocurrents produced in appropriate polarization projections. Using this scheme, we experimentally demonstrate a phase measurement with a sensitivity of 9x10(-10) rad/ radicalHz. The measurement is robust in the presence of laser frequency noise, as a result of preserving the common-path nature of the Sagnac interferometer, and of laser-amplitude noise, as a result of balanced detection.
authors.forename: K X
authors.initials: KX
authors.lastname: Sun
authors.forename: E K
authors.initials: EK
authors.lastname: Gustafson
authors.forename: M M
authors.initials: MM
authors.lastname: Fejer
authors.forename: R L
authors.initials: RL
authors.lastname: Byer