Large-Capacity Interrogation for Ultra-Weak Fiber Bragg Grating Array With a DFB Laser Array Chip

A large-capacity ultra-weak fiber Bragg grating (UW-FBG) array interrogation system is proposed and implemented. The system utilizes time- and wavelength-division multiplexing methods, based on a large-range tunable laser source (TLS) with fast tuning capability. The TLS consists of a distributed feedback multi-wavelength laser array (DFB-MLA) with a wavelength tuning range of 40 nm, which is realized using the reconstruction-equivalent-chirp (REC) technique. An external SOA modulator is used to modulate the output light from the TLS into nanosecond pulsed light. We establish an experimental system and successfully achieve 50 UW-FBGs interrogation. We perform temperature, strain, and vibration sensing experiments with a interrogation linearity of above 0.9995 and an error of less than 4 pm. Theoretically, the system is estimated to have an interrogation capability of more than 10,000 UW-FBGs, and the minimum spacing of adjacent UW-FBGs is 0.4 m. This research has made significant advancements in the multiplexing capability and spatial resolution of the UW-FBG array interrogation technology, offering important application potential in fields such as battery pack, structural health monitoring, and aerospace.