Highly sensitive sensor for simultaneous underwater measurement of salinity and temperature based on highly birefringent asymmetric photonic crystal fiber

• DOI: 10.1016/j.rio.2023.100406
• Publication Date: 2023-03-10T07:54:18Z
• Authors: Xingyu Liu; Bin Yin; Haisu Li; Muguang Wang; Ran Yan; Yongchang Li; Chenxi Zong; Songhua Wu
• Keywords: Two-parameter measurement; Sensitivity; Optical fiber sensors; Photonic crystal fiber; Temperature sensors; Salinity sensors; QC350-467; Optics. Light; 01 natural sciences; 0104 chemical sciences

This paper describes a novel compact fiber sensor with high sensitivity for the simultaneous measurement of underwater salinity and temperature by simulation. The structure is based on a highly birefringent, asymmetric, full-circular hole photonic crystal fiber (HB-A-FCH PCF), which achieves the birefringence value of 2.83 × 10-3 at the wavelength of 2.2 µm. In addition, with ethanol-filled specific air holes, the temperature sensitivity of HB-A-FCH PCF is remarkably improved. Therefore, considering the high birefringence property, we simulate a Michelson interferometer-based sensor setup with air holes as fluid microchannels and simultaneously measure salinity and temperature through the spectral responses of the x- and y-polarization state. Theoretical analysis shows the sensor can achieve the salinity and temperature sensitivity up to 5.1472 nm/% and −0.8987 nm/°C in x-polarized fundamental mode, respectively, whereas the salinity and temperature sensitivity up to 4.5386 nm/% and −0.8000 nm/°C in y-polarized fundamental mode, respectively.