High-temperature measurement using fiber Bragg grating sensor accompanied by a low-cost detection system

A fiber Bragg grating (FBG)–based high-temperature sensor accompanied by a low-cost interrogation scheme with liquid-crystal display (LCD) has been designed, developed, and tested. The sensor probe is configured by encapsulating a femtosecond laser drawn FBG with an aluminum nitride capillary tube, and is used to measure the temperature from 20°C to 650°C. The interrogation system consists of a long period fiber grating, two photodiodes, a 2-channel transimpedance amplifier, and a field-programmable gate array with an LCD. It displays the temperature directly in °C with a resolution of 1°C. The sensor output is found to be linear with coefficient of 0.999, and independent of source power fluctuations. The results showed that the sensor has good accuracy with a negligible error bar of ±1.23%.