title: Low-coherence heterodyne interferometry using an achromatic frequency shifter based on a frequency-domain optical delay line.
abstract: In this paper a high-sensitivity low-coherence heterodyne interferometric system consisting of two polarizing Michelson interferometers arranged in tandem is presented. A compact frequency-domain optical delay line was placed in the first interferometer to produce a 4.4 kHz frequency shift for broadband near-infrared light. The frequency shift was wavelength independent because the scanning delay line had a zero-group-delay configuration. The fringe amplitude and phase of a low-coherence interference signal were detected using a lock-in amplifier. The experimental results show that the signal-to-noise ratio in the proposed technique is more than 30-fold higher than that of conventional low-coherence homodyne interferometry.
authors.forename: Sheng-Hua
authors.initials: SH
authors.lastname: Lu
authors.forename: Hsiao-Ping
authors.initials: HP
authors.lastname: Chiang
authors.forename: Che-Yu
authors.initials: CY
authors.lastname: Lin
authors.forename: Che-Chung
authors.initials: CC
authors.lastname: Chou