Details

Autor(en) / Beteiligte

• Wang, Jianuo
• Zhou, Xinlei
• Miao, Yongfei
• Jiang, Gaocheng
• Tong, Lili
• Tao, Pengcheng
• Yu, Qingxu
• Peng, Wei

Titel

Integrated and compact fiber-optic conductivity-temperature-depth (CTD) sensor for marine detection

Ist Teil von

• Optics and laser technology, 2023-09, Vol.164, p.109523, Article 109523

Ort / Verlag

Elsevier Ltd

Erscheinungsjahr

2023

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• •A fiber-optic CTD sensor for simultaneous detection of temperature, salinity, depth is proposed.•The FBG with the lamellar PI coating is presented for detection of salinity with high sensitivity.•The Gaussian elimination method is employed to eliminate the cross-sensitivity effects.•The fiber-optic CDT sensor has high sensitivity, high resolution and high repeatability. Conductivity, temperature and depth (CTD) are the three most important parameters of the marine environment. In this paper, an integrated and compact fiber-optic CTD sensor for simultaneous measurement of ocean temperature, salinity (conductivity) and pressure (depth) is proposed. A bare fiber Bragg grating (FBG) for temperature measurement, an FBG with lamellar polyimide (PI) coating for salinity measurement and a diaphragm-based extrinsic Fabry-Perot interferometer (DEFPI) for pressure measurement are connected in series with only one single fiber to form a multiplexed sensing system for CTD detection. The salinity sensing mechanism based on the water diffusion model of the lamellar PI coating is presented. A mold for curing the lamellar PI coating is fabricated and the curing process is introduced in detail. Experimental setup is built for temperature, salinity and pressure measurement. The wavelength-division multiplexing (WDM) technology combined with Gaussian fitting method and the cross-correlation demodulation algorithms are employed to demodulate the measurand from the spectrum. The Gaussian elimination method is used to eliminate the cross-sensitivity effects of the three measurands. Experimental results show that a sensitivity of 10 pm/°C, 141 pm/(mol/L) and 520 nm/MPa for temperature, salinity and pressure measurement, respectively, has been realized. Resolution measurements show that a resolution of 0.1 °C, 0.01 mol and 1.5 KPa for temperature, salinity and pressure measurement, respectively, is achieved. The repeatability of the proposed CTD sensor is also be investigated and a repeatability of 0.73 % FS, 0.72 % FS and 0.1 % FS for temperature, salinity and pressure measurement, respectively, has been obtained. The proposed fiber-optic CDT sensor has the advantages of high-sensitivity, high resolution, high reliability, anti-electromagnetic interference, compact size and low cost, which has great application potential in ocean exploration.