A fiber Bragg grating sensor for simultaneous static and dynamic strain detection is hereby presented. The principle of
operation of the interrogator is based on direct intensity detection: a fixed-wavelength laser source is filtered through the
sensing element, and the output power is detected with a photodiode. Multiple sensing for matched-wavelength gratings
is performed by splitting the source into multiple channels. The exploitation of cheap components for optical
telecommunications results in a low-cost hardware solution that matches several budget-constrained applications. The
optical sensor is complemented by signal processing techniques (adaptive filters, spectral estimation, data modeling),
capable of improving performances of the system without changing the optical layout.
The system has been tested both in static interrogation, as a temperature sensor, and as vibration detector in a typical
structural monitoring context. The maximum interrogation range is ~200με, depending on the grating shape, with a
resolution <<1 με, and a repeatability of ~1%. A 1% stability over long time has been assessed with a long-term test. The
adaptive filtering improves the signal-to-noise ratio of 5.3 dB. The resolution-unlimited spectral estimator resolves
resonance peak detection for a vibration of 0.1με.