We describe a free-space common-path polarization Sagnac interferometer. The polarization Sagnac interferometer is used in a symmetric fashion with detection on the dark fringe of the interference to avoid photodetector saturation when high-powered illumination is used. By modulating the carrier field that is reflected from the interferometer, we generate a local oscillator for heterodyne detection of the signal field. We calculate the effect of optical element misalignments and imperfect polarization on the shot-noise–limited sensitivity of the interferometer. The predictions are experimentally verified with a 2-m arm-length tabletop polarization Sagnac interferometer.
© 1999 Optical Society of America
(120.2130) Instrumentation, measurement, and metrology : Ellipsometry and polarimetry
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(120.5790) Instrumentation, measurement, and metrology : Sagnac effect
Peter T. Beyersdorf, Martin M. Fejer, and Robert L. Byer, "Polarization Sagnac interferometer with a common-path local oscillator for heterodyne detection," J. Opt. Soc. Am. B 16, 1354-1358 (1999)