High-sensitivity bending vector sensor based on γ-shaped long-period fiber grating

Abstract We investigate and prepare a novel long-period fiber grating (LPFG) based on γ-shaped grid for high sensitivity bending measurement. The γ-shaped LPFG is composed of a string of γ-shaped grids, which can provide stronger refractive index modulation than normal planar grids and bring a higher sensitivity. The experimental results show the bending sensitivity of the γ-shaped LPFG reaches −21.66 nm/m−1 within the bending range of 0–2.2 m−1, and the goodness of fit value is over 0.99. Compared with the reported structure, the γ-shaped LPFG not only has high bending sensitivity and good linear fit value, but also makes the structure of LPFG more plentiful and diverse by virtue of its ultracompact structure and adjustable parameters of asymmetric grid. In addition, it is expected that more structural forms of sensor devices can be made based on LPFG to enrich the field of sensing applications and enhance the sensitivity.