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A single-measurement sweep-free distributed Brillouin optical time domain analyzer (BOTDA) sensor based on phase detection is proposed and experimentally demonstrated employing digital optical frequency comb (DOFC) probe signal. Brillouin Phase Spectrum (BPS) of DOFC probe induced by Brillouin interaction is measured using coherent detection in a single acquisition, without any frequency scanning and data averaging. Single-measurement BOTDA sensor based on BPS in 10km long fiber is demonstrated with a response time of 100 μs, which is limited only by the fiber length. The spatial resolution is 51.2m, determined by the duration of DOFC. And the Brillouin frequency shift (BFS) uncertainty is estimated to be~1.5 MHz at the end of fiber under test (FUT). Benefiting from the fast response time, dynamic measurement up to 1 kHz vibration frequency has been demonstrated.

A novel design of fiber Bragg grating (FBG) based accelerometer is proposed in this paper. The chirp-free mechanism on the FBG sensing element is the methodology employed in this design. The sensor has the flexibility to apply different mechanical parameters, and it shows excellent performance to different applied signals. The performance is then optimized by varying different configuration of the sensor. Good sensitivity (18µε/g) and signal-to-noise ratio (20.68dB re nm/g) is easily achieved. Maximum input signal frequency up to 150Hz is able to be caught up by the specific configuration of the accelerometer. The accelerometer also has the capability of capturing a full sine wave input signal with the maximum peak-to-peak amplitude up to 3.9nm.

Embedded actuator and sensor technology provides accurate structural health monitoring and proper structural response of a structure at any harsh servicing situation. This paper describes the fabrication of a smart composite by embedding shape memory alloy (SMA) wires and fibre Bragg grating (FBG) sensors into a glass fabric reinforced polymeric composite. Mechanical performances of the composite under martensitic and austenitic stages of the SMA wires were studied, and its natural frequencies were also measured accordingly. The result shows that the shift of the natural frequency arises from temperature change, thus changing the mechanical

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