Fiber Bragg grating sensor for detecting temperature and flowvelocity

A novel aluminum plate based fiber Bragg grating (FBG) sensor is proposed to detect temperature and flowvelocity. Fiber Bragg grating (FBG) was sealed on an aluminum plate by a hightemperatureresistant glue, then placed in a thermostat for solidification so as to retain the stability of FBG. The temperature and flowvelocity sensing characteristics of the encapsulated FBG sensor were theoretically and experimentally studied. Encapsulated FBG sensor was placed in a digital thermostat to detect its temperature characteristics. In the temperature range of -20℃～100℃, the experiment result indicates that the temperature sensing sensitivity coefficient of encapsulated FBG sensor is 0.0392nm/℃ and is 3.5 times as much as that of bare FBG. The temperature response curve of the encapsulated FBG sensor keeps very good linearity and repetition. In the flowvelocity experiment, the reflection peakwavelength of the encapsulated FBG sensor moved 0.13nm when the flowvelocity changed from 0 to 20m/s with constant water temperature at 14.5℃. So it is feasible to use the encapsulated FBG sensor to detect the flowvelocity. The result proves that the aluminum plate encapsulated FBG sensor can detect temperature and flowvelocity. The encapsulated FBG sensor is easy to make, cost effective and practical.