Multi-taper array for dynamic strain measurements by a Brillouin optical frequency-domain analysis

In this manuscript, we demonstrate that an array of tapers, consecutively formed along a single-mode optical fiber, can be used to realize a localized, dynamic strain sensing position with a Brillouin Optical Frequency-Domain Analysis (BOFDA) sensor. The multi-taper realizes a periodic modulation of the Brillouin frequency shift, which appears as a spectral resonance in the baseband transfer function acquired by the BOFDA sensor. Any strain acting along the multi-taper affects the magnitude of this resonance, offering a means to perform dynamic strain measurements in that position. Fabricating multi-taper arrays with a different period, more dynamic sensing positions can be realized along the same fiber. Measurements on two vibrating cantilevers were performed at a sampling rate of 46 Hz, using two multi-taper arrays with a length of 72 mm and 75 mm, respectively.