Sub-chirp-multiplexed spectral matching-enabled FMCW-DAS with enhanced frequency and strain ranges
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Updated: Nov 1, 2026

Multiplex Chemical Imaging Based on Broadband Stimulated Raman Scattering Microscopy
Published on: July 25, 2022
Can Chen1, Zhonghong Lin1, Zhiyong Zhao1
1Wuhan National Lab for Optoelectronics (WNLO) & National Engineering Laboratory for Next Generation Internet Access System, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China.
Abstract:
We propose what we believe to be a novel frequency-modulated continuous-wave distributed acoustic sensing (FMCW-DAS) system utilizing the sub-chirp-multiplexed spectral matching (SCM-SM) method. Multiplexing N sub-chirp probe signals enhances the theoretical maximum measurable frequency N-fold beyond the conventional single-shot limit. By extracting strain via sub-chirp spectral matching rather than phase demodulation, the measurable range is solely governed by the sub-chirp bandwidth, which enables large-strain detection with high spatial resolution while fundamentally eliminating the strict inter-frequency phase alignment required in conventional frequency-division multiplexing schemes, thereby exhibiting intrinsically high measurement reliability. A proof-of-concept experiment interrogating a 10-km fiber with an 8-GHz, 125-µs FMCW signal achieved a 40-kHz effective sampling rate and a 10.5-µε theoretical maximum measurable strain at a 2.5-m spatial resolution. This scheme provides a robust paradigm for simultaneous high-frequency and large-strain distributed acoustic sensing.
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