Distributed Sensing System of Optical Low-Coherence Reflectometry Using an Array of Identical Fiber Bragg Gratings

The optical low-coherent interferometric technology for Fiber Bragg grating (FBG) sensing array is described. The sensing array is formed by a series of identical FBGs with low reflectivity (5.25%), where the first FBG acts as a reference (shielded from the measurand), and the other FBGs work as sensors. Each sensing-FBG and the reference-FBG can form a Fabry-Perot (F-P) interferometer with a specific cavity length. By scanning a home-made optical low-coherence reflectometry (OLCR), the signals corresponding to different sensing-FBGs (F-P interferometers) can be obtained and well distinguished. A measurement of temperature is demonstrated and it shows good performance of the scheme.