title: In-line interferometer for direction-sensitive displacement measurements by optical feedback detection.
abstract: We demonstrate a compact in-line interferometer for direction-sensitive displacement measurement by optical feedback detection with a semiconductor laser (SL) light source. Two reflected beams from a semitransparent reference mirror and a reflecting test object interfere in the SL medium, causing a variation in its output power. The reference mirror is located between the SL output facet and the test object. The performance of the interferometer is investigated numerically and experimentally to determine its optimal operating conditions. We have verified the operating conditions where the behavior of the SL output power profile could indicate accurately the displacement magnitude and direction of the moving test object. The profile behavior is robust against variations in optical feedback and scale of the interferometer configuration.
authors.affiliation: National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101, Philippines.
authors.forename: Alvarado
authors.initials: A
authors.lastname: Tarun
authors.forename: Julius
authors.initials: J
authors.lastname: Jecong
authors.forename: Caesar
authors.initials: C
authors.lastname: Saloma