A fiber Bragg grating dynamic stress sensing interrogation system with high interrogation rate

摘要

Dynamic stress sensing interrogation has become into a potential research for its wide applications. In order to test and monitor the dynamic stress in real-time, new types of fiber Bragg gratings (FBGs) sensing interrogation systems have been gradually developed. In this paper, a high interrogation rate dynamic stress sensing interrogation system by using a wavelength-swept laser with high sweeping rate and flexible-controlled sweeping step is proposed and demonstrated. In this system, a single sideband (SSB) modulator driven by radio-frequency (RF) signal is used to realize the above-mentioned parameters of the wavelength-swept laser, which overcomes the limitation of traditional mechanical sweeping devices. The interrogation rate of the whole system is decided by the sweeping rate of the source, which is significantly improved and tunable with a broad range. Owing to the advantages of the sweeping source, our sensing interrogation system is effective to deal with different vibration sensing interrogations. Experimentally, the sweeping rate of the wavelength-swept laser can be tuned from 40 kHz to 200 kHz as sweeping step tuned from 5 GHz to 15 GHz. The highspeed vibration generated by a piezoelectric transducer (PZT) on the FBGs is sensed and interrogated in real-time. The interrogation of frequency vibration sensing from 5 Hz to 11 kHz are obtained. A 25 μs transient vibration mutation is also successfully interrogated by this system.