Hybrid Interrogation System for Distributed Fiber Strain Sensors and Point Temperature Sensors Based on Pulse Correlation and FBGs

A hybrid interrogation scheme for distributed strain sensors and point temperature sensors is proposed and its feasibility is demonstrated. It exploits the advantages of distributed sensors and point sensors simultaneously. The proposed interrogation scheme uses a wavelength tunable pulse source and wavelength-dependent reflectors for region selective sensing. Experimental results confirm its linear response and a resolution of 0.02% of the total dynamic range, which in our experiment is over 2000 microstrains for sensing regions of around a 0.5-m length. The stability of the measurements is over 99.8%. Finally, the high input power from the signal source and the limited losses from the reflectors allow the usage of a large number of sensors in a fiber.