title: Measurement of absolute frequency of continuous-wave terahertz radiation in real time using a free-running, dual-wavelength mode-locked, erbium-doped fibre laser.
abstract: A single, free-running, dual-wavelength mode-locked, erbium-doped fibre laser was exploited to measure the absolute frequency of continuous-wave terahertz (CW-THz) radiation in real time using dual THz combs of photo-carriers (dual PC-THz combs). Two independent mode-locked laser beams with different wavelengths and different repetition frequencies were generated from this laser and were used to generate dual PC-THz combs having different frequency spacings in photoconductive antennae. Based on the dual PC-THz combs, the absolute frequency of CW-THz radiation was determined with a relative precision of 1.2 × 10-9and a relative accuracy of 1.4 × 10-9at a sampling rate of 100 Hz. Real-time determination of the absolute frequency of CW-THz radiation varying over a few tens of GHz was also demonstrated. Use of a single dual-wavelength mode-locked fibre laser, in place of dual mode-locked lasers, greatly reduced the size, complexity, and cost of the measurement system while maintaining the real-time capability and high measurement precision.
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Hu
authors.affiliation: Graduate School of Science and Technology, Tokushima University, 2-1 Minami-Josanjima, Tokushima 770-8506, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Mizuguchi
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Graduate School of Science and Technology, Tokushima University, 2-1 Minami-Josanjima, Tokushima 770-8506, Japan.|JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1 Minami-Josanjima, Tokushima 770-8506, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Minamikawa
authors.affiliation: Graduate School of Science and Technology, Tokushima University, 2-1 Minami-Josanjima, Tokushima 770-8506, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Mizuno
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China.
authors.forename: Yuli
authors.initials: Y
authors.lastname: Yang
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China.
authors.forename: Cui
authors.initials: C
authors.lastname: Li
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Bai
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China.|Collaborative Innovation Centre of Geospatial Technology, 129 Luoyu Road, Wuhan 430079, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Graduate School of Science and Technology, Tokushima University, 2-1 Minami-Josanjima, Tokushima 770-8506, Japan.|JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1 Minami-Josanjima, Tokushima 770-8506, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yasui