Long period fibre gratings for structural bend sensing

Abstract
The authors examine the changes in wavelength and attenuation of long period fibre gratings subjected to bends with curvatures from 0 to 4.4 m–1. The wavelength change with curvature is nonlinear, with a projected minimum detectable curvature change of 2 × 10–3 m–1. The magnitude of the bend-induced wavelength shift depends on the rotation of the cylindrical fibre relative to the bending plane.