Embedded long-period fiber grating bending sensor

The use of embedded long-period grating (ELPG) in carbon–fiber composite laminate for bending measurement has been demonstrated in this paper. As the bending curvature increases on the ELPG laminate, the coupling strength of the cladding mode decreases while the resonance wavelength remains relatively constant. The ELPG yields a sensitivity of 5.065 dB m−1 and repeatability of 98.1% up to a bending curvature of 2 m−1. It also can be used to determine direction of the bend.