Tunable quantum cascade VECSELs above 5 THz

We demonstrate a quantum-cascade (QC) laser above 5 THz in a metasurface VECSEL architecture using hybrid bound-to-continuum/resonant-phonon active region. Broadband THz QC-lasers in the 5 – 6 THz range are desirable for spectroscopic applications, however development in THz QCLs above 5 THz has been limited due to the challenges in the laser active region design and increased material losses. Furthermore, implementing metasurface VECSELs introduces further challenges due to unfavorable electromagnetic scaling relations of the amplifying metasurface. Initial results of the QC-VECSEL were successful in pulsed mode operation, with power output of 1.3 mW as well as single-mode tuning from 5.40 – 5.72 THz as the output coupler is mechanically stepped. The device lased up to a maximum heatsink temperature of 50 K.