A highly sensitive curvature sensor based on Omega shaped long-period fiber grating

A compact Omega shaped long-period fiber grating (OS-LPFG) for vector bending measurement is proposed and investigated in this paper. This sensor is fabricated by periodically splicing single-mode fiber (SMF) and multi-mode fiber (MMF) into Omega shape to get the purpose of sensitivity enhancing. The proposed OS-LPFG can distinguish the bending direction and achieves the curvature sensitivities in X, Y, -X directions are 12.03 nm/m -1 , -69.95 nm/m -1 and -19.84 nm/m -1 at the range of 0 m -1 to 1.5 m -1 . Meanwhile, the sensor has a small temperature crosstalk of 0.0011 m -1 /°C at the temperature range of 20 °C to 110 °C. In addition, the sensor features a compact structure with the length of 1.5 mm due to the strong refractive index modulation induced by fabricating method, which proposes a feasible idea for compact fiber curvature sensor design.