title: Variable-frequency lock-in detection for the suppression of beat noise in Brillouin optical correlation domain analysis.
abstract: We propose and experimentally demonstrate a novel lock-in detection method to avoid a beat noise in Brillouin optical correlation domain analysis (BOCDA) which appears in the sweep of the sensing position and deteriorates the measurement accuracy by distorting the acquired Brillouin gain spectrum. In our analysis, the origin of the beat noise is shown to be the fluctuation of the Brillouin gain induced by the chopping of the intensity-modulated pump wave, and the optimal relation between the modulation and the lock-in frequencies is developed as an effective solution to circumvent the beat noise.
authors.affiliation: Nanophotonics Center, Korea Institute of Science and Technology (KIST), Seoul, Korea.
authors.forename: Ji Ho
authors.initials: JH
authors.lastname: Jeong
authors.forename: Kwanil
authors.initials: K
authors.lastname: Lee
authors.forename: Kwang Yong
authors.initials: KY
authors.lastname: Song
authors.forename: Je-Myung
authors.initials: JM
authors.lastname: Jeong
authors.forename: Sang Bae
authors.initials: SB
authors.lastname: Lee