Compact Fiber Sensor With High Spatial Resolution for Simultaneous Strain and Temperature Measurement

A compact fiber sensor based on fiber Bragg grating (FBG) embedded in a fiber modal interferometer (MI) for simultaneous measurement of strain and temperature is proposed. Because the total length of the sensor is 12 mm and can be further reduced, the spatial resolution of the sensor is improved. Due to the different responses of the fiber MI and the FBG to strain and temperature, the simultaneous measurement at the same point is achieved. For 0.01-nm wavelength resolution, the resolution of the sensor is 5.96 ${\mu}{\varepsilon }$ and 0.31 $^{\circ}{\rm C}$ in strain and temperature, respectively.