Quantum cascade laser frequency comb at 5 THz

As a compact light source with high output power, quantum cascade laser has excellent performance in the range of 1-5THz. By using THz QCL optical comb spectrum in this frequency range, drugs and industrial waste gas can be quickly and effectively detected and identified. In this paper, we report a semi-insulating surface-plasmon waveguide THz QCL emitting at 5 THz operating in continuous-wave mode at 4K. For the device with 3-mm-long cavity and 150-µm-wide ridge, the continuous peak power is up to 13mW and the total spectral range is about 5cm
^-1
. Furthermore, the stable optical comb is achieved in the range of 0.93-1.11A.