Precise Evaluation of a Phase-Locked THz Quantum Cascade Laser

• Published in: IEEE transactions on terahertz science and technology Vol. 6; no. 1; pp. 115 - 120
• Main Authors: Irimajiri, Yoshihisa, Kumagai, Motohiro, Morohashi, Isao, Kawakami, Akira, Nagano, Shigeo, Sekine, Norihiko, Ochiai, Satoshi, Tanaka, Shukichi, Hanado, Yuko, Uzawa, Yoshinori, Hosako, Iwao
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.01.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Frequency instability; Harmonic analysis; hot electron bolometer mixer (HEBM); Hot electrons; Instability; Microwave oscillators; Microwaves; Mixers; Oscillators; Phase noise; phase-locking; Quantum cascade lasers; Receivers; Superconductivity; Superlattices; Synthesizers; terahertz quantum cascade laser (THz-QCL)
• ISSN: 2156-342X; 2156-3446
• DOI: 10.1109/TTHZ.2015.2504792

We have demonstrated the phase-locking of a THz quantum cascade laser (THz-QCL) toward the realization of an accurate and stable local oscillator for a high-resolution receiver. The beat note between the THz-QCL and a THz reference was obtained by heterodyne mixing in a superconducting hot electron bolometer mixer (HEBM) and used for stabilizing the phase of 3.1 THz radiation from the THz-QCL. The phase-locked 3.1 THz radiation was fully evaluated with a superlattice harmonic mixer operating in the THz band, and this revealed that the THz-QCL synchronized with the microwave reference with a fractional frequency instability of 3×10 -15 at an averaging time of 100 s, corresponding to a center frequency deviation within 1 mHz, and the imposed phase noises during the heterodyne mixing were negligibly small.