A Highly Sensitive Temperature Sensor Based on Power Changes of Fiber Bragg Grating Pairs

A highly sensitive temperature sensor based on power change of double fiber Bragg gratings (FBGs) structure is proposed in this letter. It consists of two identical FBGs (FBG1, FBG2), in which the Bragg wavelength of FBG1 is modulated by the temperature and its reflecting light is injected into FBG2. Thus, the power difference of two peaks that appear in the transmission spectrum of FBG2 can be modulated by temperature around FBG1. By shifting the Bragg wavelength of FBG2, the sensor can achieve the segmental measurement of temperature. In the experiment, dynamic range of 25 °C-135 °C and sensitivity of 1.35 ± 0.02 dBm/°C have been achieved.