Laser & Infrared, Volume. 55, Issue 7, 1148(2025)
Design of sensitized FBG sensor for underwater depth detection
To improve the sensitivity and stability of underwater depth detection, an enhanced packaging structure was designed. A novel design combining a sensitization bridge with a cavity structure is adopted to improve the sensitivity of FBG (Fiber Bragg Grating) sensors. FBG1 is fixed at the connection between the soft silicone top cover and the sensitization bridge, and tightly adheres to the sealant. FBG2 is secured at the bottom of a hard sealed shell to form a cavity type sensitization structure. FBG1 is highly sensitive to water pressure caused by water depth, and the functional relationship between wavelength variation of FBG1 and water depth is derived. FBG2 is used to compensate for FBG1 temperature offset. The correspondence between water depth and structural parameters is analyzed through simulation, and the deformation degree of the sensitized bridge under different external force conditions is compared. In an experimental test conducted in a 1.8 m deep swimming pool, this sensor is compared with a traditional multi-layer structured FBG sensor. The results show that the total wavelength change of the traditional structure is 1.524 nm, and the depth sensitivity is 8.4 pm/cm. After sensitization optimization, the total wavelength change can reach 3.312 nm, the depth sensitivity is increased to 1.84 pm/mm, and the average error is reduced by 28.9%. The feasibility of the sensitized design is thus verified.
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LIANG Fang, LIAO Jian-jun, XUN Yan-qin, FU Jian-mei, ZHANG Qiong, DING Wei-jie. Design of sensitized FBG sensor for underwater depth detection[J]. Laser & Infrared, 2025, 55(7): 1148
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Received: Oct. 22, 2024
Accepted: Sep. 12, 2025
Published Online: Sep. 12, 2025
The Author Email: LIAO Jian-jun (liaojianjun008@163.com)