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arXiv · 1501.06251

Real-time absolute frequency measurement of continuous-wave terahertz wave based on dual terahertz combs of photocarriers with different frequency spacings

Takeshi Yasui·Kenta Hayashi·Ryuji Ichikawa·Harsono Cahyadi·Yi-Da Hsieh·Yasuhiro Mizutani·Hirotsugu Yamamoto·Tetsuo Iwata·Hajime Inaba·Kaoru Minoshima
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Abstract

Real-time measurement of the absolute frequency of continuous-wave terahertz (CW-THz) waves is required for characterization and frequency calibration of practical CW-THz sources. We proposed a method for real-time monitoring of the absolute frequency of CW-THz waves involving temporally parallel, i.e., simultaneous, measurement of two pairs of beat frequencies and laser repetition frequencies based on dual THz combs of photocarriers (PC-THz combs) with different frequency spacings. To demonstrate the method, THz-comb-referenced spectrum analyzers were constructed with a dual configuration based on dual femtosecond lasers. Regardless of the presence or absence of frequency control in the PC-THz combs, a frequency precision of 10-11 was achieved at a measurement rate of 100 Hz. Furthermore, large fluctuation of the CW-THz frequencies, crossing several modes of the PC-THz combs, was correctly monitored in real time. The proposed method will be a powerful tool for the research and development of practical CW-THz sources, and other applications.

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Takeshi Yasui, Kenta Hayashi, Ryuji Ichikawa, Harsono Cahyadi, Yi-Da Hsieh, Yasuhiro Mizutani, Hirotsugu Yamamoto, Tetsuo Iwata, Hajime Inaba, Kaoru Minoshima. 2015-01-26. Real-time absolute frequency measurement of continuous-wave terahertz wave based on dual terahertz combs of photocarriers with different frequency spacings. https://doi.org/10.1364/oe.23.011367

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