Our recent paper “Multi-bounce self-mixing in terahertz metasurface external-cavity lasers” has been highlighted as an Editor’s Pick in Optics Express! We investigated the effect of controlled optical feedback of a THz QC-VECSEL for the first time, and showed that (a) compared with waveguide-based THz QCLs, THz QC-VECSELs are particularly sensitive to optical feedback due to their large emitting aperture, and (b) the feedback is dominated by light circulating over multiple round-trips in the external cavity. While often undesirable, the self-mixing phenomenon can be harnessed for a variety of THz sensing and imaging applications, without the need for an external detector.

Anthony D. Kim, Daniel McGovern*, and Benjamin S. Williams, “Multi-bounce self-mixing in terahertz metasurface external-cavity lasers,” Optics Express, vol. 32, 18880-18895 (2024). https://doi.org/10.1364/OE.523012