Skip to main content
placeholder image

Displacement sensing using the relaxation oscillation frequency of a laser diode with optical feedback

Journal Article


Abstract


  • A laser diode (LD) with external optical feedback can generate undamped relaxation oscillation (RO) under certain operational conditions. The RO frequency can be modified by the external cavity length of the LD and is highly sensitive to the variation of the cavity length (ΔL). This work first investigates the relationship between the RO frequency and ΔL by solving the well-known Lang–Kobayashi (L–K) equations and then verifies the relationship by experiments. Both theory and experiment show that the RO frequency changes in a sawtooth-like quasi-periodic manner with respect to ΔL. The fundamental period is half laser wavelength. This sawtooth feature enables us to achieve period unwrapping and thus extend the measurement range up to a few micrometers. This work shows a possible new solution for achieving high-resolution, large-range displacement measurements.

Publication Date


  • 2017

Citation


  • B. Liu, Y. Yu, J. Xi, Q. Guo, J. Tong & R. A. Lewis, "Displacement sensing using the relaxation oscillation frequency of a laser diode with optical feedback," Applied Optics, vol. 56, (24) pp. 6962-6966, 2017.

Scopus Eid


  • 2-s2.0-85027560737

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers1/566

Number Of Pages


  • 4

Start Page


  • 6962

End Page


  • 6966

Volume


  • 56

Issue


  • 24

Place Of Publication


  • United States

Abstract


  • A laser diode (LD) with external optical feedback can generate undamped relaxation oscillation (RO) under certain operational conditions. The RO frequency can be modified by the external cavity length of the LD and is highly sensitive to the variation of the cavity length (ΔL). This work first investigates the relationship between the RO frequency and ΔL by solving the well-known Lang–Kobayashi (L–K) equations and then verifies the relationship by experiments. Both theory and experiment show that the RO frequency changes in a sawtooth-like quasi-periodic manner with respect to ΔL. The fundamental period is half laser wavelength. This sawtooth feature enables us to achieve period unwrapping and thus extend the measurement range up to a few micrometers. This work shows a possible new solution for achieving high-resolution, large-range displacement measurements.

Publication Date


  • 2017

Citation


  • B. Liu, Y. Yu, J. Xi, Q. Guo, J. Tong & R. A. Lewis, "Displacement sensing using the relaxation oscillation frequency of a laser diode with optical feedback," Applied Optics, vol. 56, (24) pp. 6962-6966, 2017.

Scopus Eid


  • 2-s2.0-85027560737

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers1/566

Number Of Pages


  • 4

Start Page


  • 6962

End Page


  • 6966

Volume


  • 56

Issue


  • 24

Place Of Publication


  • United States