title: Optical feedback laser with a quartz crystal plate in the external cavity.
abstract: We studied the optical feedback characteristics of a single-mode He-Ne laser with a quartz crystal plate in the external cavity. The fringe frequency of the laser system can be doubled when the quartz crystal plate is positioned at a certain angle between the crystalline axis and the beam in the crystal plate. Theoretical analysis shows that the birefringent effect of the quartz crystal plate and the laser beam's second pass through the external cavity result in this phenomenon. The experimental results are in good agreement with the theoretical analysis. A quartz crystal plate can double the resolution of a self-mixing sensing system.
authors.affiliation: State Key Laboratory of Precision Measurement Technology, Department of Precision Instruments, Tsinghua University, Beijing 100084, China. liugang98@mails.tsinghua.edu.cn
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Shulian
authors.initials: S
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: Yan
authors.initials: Y
authors.lastname: Li