A compact multifunctional fiber sensor for simultaneous underwater measurement of salinity, temperature and strain. (15th May 2022) - Sang, Guofeng
Highlights: A compact multifunctional underwater optical fiber sensor based on SPNPS-PMFBG structure is proposed and experimentally demonstrated. By monitoring the wavelength and output power change of PMFBG at two resonance peaks, the synchronous measurement of salinity, temperature and strain are achieved. The proposed sensor has high stability with the wavelength fluctuations of less than 0.02 nm and the intensity variation of less than 0.1 dB during 3 h, and the fast response time with less than or equal to 3 s. In the experiment under water, the measured salinity sensitivity based on the sum of two resonance peaks in the range of 0–7 wt% is −0.58 dB/wt% with good linear response and repeatability. Abstract: In this paper, a compact multifunctional optical fiber sensor based on single mode fiber-photonic crystal fiber-no core fiber-photonic crystal fiber-single mode fiber-polarization maintaining fiber Bragg grating (SPNPS-PMFBG) has been proposed. By monitoring the wavelength and output power of the two resonance peaks of PMFBG, simultaneous measurement of salinity, temperature and strain can be realized. In our experiment under water, the sum output power of the two resonance peaks in 0–7 wt% salinity shows a good linear relationship and repeatability, and the sensitivity is −0.58 dB/wt% with 3 s response time. In addition, the measured temperature wavelength sensitivities at two resonance peaks are 0.042 nm/°C and 0.040 pm/°C, and the output power sensitivities are approximate to 0.079 dB/°C and 0.081 dB/°C, respectively. Further, the strain wavelength sensitivities are 0.535 nm/1000 μ ε, and the output power sensitivities are 0.65 dB/1000 μ ε and 0.70 dB/1000 μ ε .