Vernier spectrometer using counterpropagating soliton microcombs.

Yang, Qi-Fan; Shen, Boqiang; Wang, Heming; Tran, Minh; Zhang, Zhewei; Yang, Ki Youl; Wu, Lue; Bao, Chengying et al. · Science · 2019

basic_science · Level V

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Abstract

Determination of laser frequency with high resolution under continuous and abrupt tuning conditions is important for sensing, spectroscopy, and communications. We show that a single microresonator provides rapid and broadband measurement of optical frequencies with a relative frequency precision comparable to that of conventional dual-frequency comb systems. Dual-locked counterpropagating solitons having slightly different repetition rates were used to implement a vernier spectrometer, which enabled characterization of laser tuning rates as high as 10 terahertz per second, broadly step-tuned lasers, multiline laser spectra, and molecular absorption lines. Besides providing a considerable technical simplification through the dual-locked solitons and enhanced capability for measurement of arbitrarily tuned sources, our results reveal possibilities for chip-scale spectrometers that exceed the performance of tabletop grating and interferometer-based devices.