title: Environment-noise-free optical heterodyne retardation measurement using a double-pass acousto-optic frequency shifter.
abstract: We demonstrate an environment-noise-free optical heterodyne interferometer (OHI) based on a double-pass acousto-optic frequency shifter (AOFS) for phase retardation measurements. The OHI generates intermediate-frequency (IF) heterodyne beat signals for each orthogonal linear polarization mode of a birefringence sample. The phase differences of the IF signals are compared by using a wide-bandwidth lock-in amplifier. This scheme provides 20 dB rejection of common-mode environmental disturbances. Measurements of the half-wave voltage of an electro-optics modulator and the electro-optic coefficient of an LiNbO3plate are demonstrated as application examples.
authors.forename: Che-Chung
authors.initials: CC
authors.lastname: Chou
authors.forename: Shin-Yu
authors.initials: SY
authors.lastname: Lu
authors.forename: Tyson
authors.initials: T
authors.lastname: Lin
authors.forename: Sheng-Hua
authors.initials: SH
authors.lastname: Lu
authors.forename: Ru-Jong
authors.initials: RJ
authors.lastname: Jeng