An embedded FBG sensor for simultaneous measurement of stress and temperature

An embedded fiber Bragg grating (FBG) sensor for simultaneous measurement of stress and temperature is proposed, where a uniform FBG is capsulated in a tapered polymer so that the grating is linearly chirped when the sensor is stressed. The value of applied stress and temperature can be obtained by measuring the chirp and central wavelength via a coefficient matrix. Experimental results demonstrate that the sensor has a stress sensitivity of 2.62/spl times/10/sup -3/nm/N and a temperature sensitivity of 0.108 nm//spl deg/C. Since the FBG is well protected and no sudden strain change is imposed on it, the sensor is expected to have an excellent reliability.