Si lens-coupled, room-temperature quantum cascade laser sources operating in 0.4-3 THz range

Terahertz quantum cascade laser sources based on intra-cavity nonlinear frequency mixing are currently the only electrically pumped monolithic semiconductor light source operating in THz frequency range at room temperature. We demonstrated the power enhancement of the devices in 0.4-3 THz range by using a lens-coupled Cherenkov radiation scheme. Adopting this scheme, the device produces ∼1 milli-watt peak power at a frequency of 2.38 THz at room temperature, which was increased by a factor of approximately four compared to that of a conventional Cherenkov extraction scheme.