Ultra-low threshold THz microcavity lasers with sub-wavelength mode volumes

We demonstrate terahertz microcavity lasers at λ=112μm with ultra-low current thresholds of 4 mA and with mode volumes of less than one-cubic-wavelength. Confinement in the longitudinal direction is obtained using almost-circular micro-disk resonators. The guiding properties of surface-plasmons are exploited to guide the mode with the metal contact. The devices laser up to 70K in pulsed mode, and up to 60K in continuous-wave.