Microwave photonics solutions for high-throughput and data efficient optical fiber grating sensor interrogation

Despite that impressive ultra-sensitive fibre grating sensor interrogation system with sub-pm resolution has been developed, mostly overlooked in fibre grating sensors is the temporal resolution of interrogation systems, which is however important for studying dynamic phenomena and monitoring fast vibrating objects. Microwave photonics techniques provide a promising solution for ultrafast and high-resolution interrogation of fibre grating sensors. This paper reports most recent advances in developing microwave photonics solutions for high-throughput fibre grating sensor interrogation. For example, photonic time stretch technique, which uses an optical dispersive element to map the instantaneous power spectrum of an ultrashort optical pulse to a temporal waveform has enabled real-time ultrafast fibre grating sensor interrogation in the megahertz regime. The fundamental trade-off between the interrogation speed and resolution in the time stretch-based interrogation system can be completely eliminated based on interferometric temporal spectroscopy. In addition, fully-distributed fibre grating sensors with simultaneous high temporal and spatial resolution has been made possible by applying dispersion-induced optical time stretch frequency domain reflectometry. The distributed information along the sensing grating was encoded to the instantaneous RF frequency of the recorded temporal interference waveform. The strain value was measured from the change of and location was measured from the instant time. One emerging challenge in microwave photonics enabled high-throughput fibre grating sensor interrogation systems is massive data set inherently generated by the interrogation instrument. Data-efficient interrogation technique based on photonic compressive sensing is also presented to address the challenge.