PT Unknown AU Irimajiri, Y Kumagai, M Morohashi, I Kawakami, A Nagano, S Sekine, N Ochiai, S Tanaka, S Hanado, Y Uzawa, Y Hosako, I TI Phase-locking of a THz-QCL using a Low Noise HEB mixer, and a Frequency-comb as a Reference SE 39th Int. Conf. IRMMW-THz PY 2014 BP 1 EP 2 DI 10.1109/IRMMW-THz.2014.6956401 AB We have developed a phase-locking system of a 3.1THz QCL (Quantum Cascade Laser) using a low noise hot electron bolometer mixer (HEBM) and a THz reference. The THz reference was generated by photomixing two optical modes of a frequency comb. The THz-QCL and HEBM devices are fabricated in our laboratory. A line width of the phase-locked QCL of narrower than 1Hz was achieved. ER