Fig. 5: Long-distance spectral strain sensing based on phase-shifted fiber Bragg grating (PS-FBG). | Nature Communications

Fig. 5: Long-distance spectral strain sensing based on phase-shifted fiber Bragg grating (PS-FBG).

From: Single-photon dual-comb ghost imaging spectroscopy

Fig. 5

a Concept of long-distance fiber sensing using single-photon DC-GIS. b Experimental configuration. c Periodic trigger signal for avoiding the backscattering in long-distance fiber. d Reference signal recorded by DCS. e Photon-counting signal of the SPAD with a counting time of 5 μs. The photons detected within 0–1.25 ms are caused by the limited isolation (~45 dB) of the circulator and the backscattering signals, while the photons within 1.25–1.89 ms are the reflected signals of PS-FBG. f Reflected spectra of PS-FBG reconstructed by single-photon DC-GIS under different strain conditions; the solid-dot curve represents the linear relationship between the frequency shift and the applied axial strain with a slope of −4.04 με/GHz.

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