This paper introduces the continuously tunable THz radiation through sideband generation of a free running and solidnitrogen- cooled THz quantum cascade laser. The 2.324 THz QCL operating in a single longitudinal mode (SLM) in continuous-wave (cw) was mixed with a swept synthesized microwave signal by a THz Schottky-diode-balanced mixer. Through sideband generation, two frequency branches were observed at low and high frequency, characterized with a Fourier-transform spectrometer. At low frequency, the sideband generates frequencies from -50 GHz to +50 GHz. At high frequency, it generates sideband frequencies from 70 GHz to 115 GHz. The total ±100 GHz tuning range can be further expanded with higher frequency millimeter wave amplifier/multiplier source. The sideband generates total 1 μW of output power at both upper and lower frequency with 200 μW of driven power from the THz QCL, showing a power conversion efficiency of 5 × 10^-3. The demonstration of this SM, continuously tunable THz source enables its applications where SM, spatially coherent beam is required.

Date Published: 14 March 2015
PDF: 6 pages
Proc. SPIE 9362, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications VIII, 93620U (14 March 2015); doi: 10.1117/12.2175696

Published in SPIE Proceedings Vol. 9362:
Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications VIII
Laurence P. Sadwick; Tianxin Yang, Editor(s)