Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs.
Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10(-7) in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.
Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Yi-Da
YD
Hsieh
Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Yuki
Y
Iyonaga
Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Yoshiyuki
Y
Sakaguchi
1] Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan [2] Micro Optics Co., Ltd, 2-20, Oe-Nakayama, Nishikyo, Kyoto 610-1104, Japan.
Shuko
S
Yokoyama
1] National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan [2] ERATO Intelligent Optical Synthesizer Project, JST, 1-5-1, Chofugaoka, Chofu, Tokyo 182-8585, Japan.
Hajime
H
Inaba
1] ERATO Intelligent Optical Synthesizer Project, JST, 1-5-1, Chofugaoka, Chofu, Tokyo 182-8585, Japan [2] Graduate School of Informatics and Engineering, The University of Electro-Communications, 1-5-1, Chofugaoka, Chofu, Tokyo 182-8585, Japan.
Kaoru
K
Minoshima
Laboratoire de Physico-Chimie de l'Atmosphère, Université du Littoral Côte d'Opale, 189A Av. Maurice Schumann, Dunkerque 59140, France.
Francis
F
Hindle
Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Tsutomu
T
Araki
1] Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan [2] ERATO Intelligent Optical Synthesizer Project, JST, 1-5-1, Chofugaoka, Chofu, Tokyo 182-8585, Japan [3] Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Josanjima, Tokushima, Tokushima 770-8506, Japan.
Takeshi
T
Yasui