A High Spatial Resolution FBG Sensor Array for Measuring Ocean Temperature and Depth

Exploring and understanding the ocean is an important field of scientific study. Acquiring accurate and high-resolution temperature and depth profiles of the oceans over relatively short periods of time is an important basis for understanding ocean currents and other associated physical parameters. Traditional measuring instruments based on piezoelectric ceramics have a low spatial resolution and are not inherently waterproof. Meanwhile, sensing systems based on fiber Bragg grating (FBG) have the advantage of facilitating continuous measurements and allow multi-sensor distributed measurements. Therefore, in this paper, an all-fiber seawater temperature and depth-sensing array is used to obtain seawater temperature and depth profiles. In addition, by studying the encapsulation structure of the FBG sensors, this paper also solves the problem of the measurement error present in traditional FBG sensors when measuring seawater temperature. Through a theoretical analysis and seaborne test in the Yellow Sea of China, the sampling frequency of the all-fiber seawater temperature and depth profile measurement system is 1 Hz, the accuracy of the FBG sensors reaches 0.01 °C, and the accuracy of the FBG depth sensors reaches 0.1 % of the full scale. The resulting parameters for these sensors are therefore considered to be acceptable for most survey requirements in physical oceanography.