High-sensitivity pressure sensor based on tilt fibre Bragg grating radial load effect

In this paper, a simple and novel optical fibre pressure sensor with tilt fibre Bragg grating is put forward. The radial compression and rebound on tilt fibre Bragg grating (TFBG) cause grating angle and length change, meanwhile, its cladding mode spectra decrease sharply. Some transmission spectrum characteristics, such as amplitude, extinction ratio value, wavelengths of cladding and Bragg modes, are extracted and analyzed. It shows that they are nearly linear with the radial pressure on surface of bare TFBG. Among them, the extinction ratio value with high sensitivity of 0.7 dB/N can keep consistent with pressure. The max amplitudes of some cladding mode resonance are good linear with radial press with sensitivity of 0.18 dB/N. The relation between each mode resonance wavelength shift and radial press on TFBG keeps good linearity with 0.8-pm/N sensitivity. By means of choosing tygon elastic pad material imposed on bare TFBG, the pressure sensitivity with amplitude of 0.21 dB/N and extinction ratio of 0.25 dB/N is obtained in order to use in practical engineering.