© 2015 Optical Society of America. We demonstrate an active phase-nulling scheme for terahertz (THz) frequency quantum cascade lasers (QCLs) under optical feedback, by active electronic feedback control of the emission frequency. Using this scheme, the frequency tuning rate of a THz QCL is characterized, with significantly reduced experimental complexity compared to alternative approaches. Furthermore, we demonstrate real-time displacement sensing of targets, overcoming the resolution limits imposed by quantization in previously implemented fringe-counting methods. Our approach is readily applicable to high-frequency vibrometry and surface profiling of targets, as well as frequency-stabilization schemes for THz QCLs.
CITATION STYLE
Dean, P., Keeley, J., Valavanis, A., Bertling, K., Lim, Y. L., Taimre, T., … Davies, A. G. (2015). Active phase-nulling of the self-mixing phase in a terahertz frequency quantum cascade laser. Optics Letters, 40(6), 950. https://doi.org/10.1364/ol.40.000950
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