Curvature sensor based on a fibre loop mirror using a highly birefringent photonic crystal fibre with two asymmetric hole regions

Abstract

In this work, a curvature sensor based on a highly birefringent (Hi-Bi) photonic crystal fibre loop mirror is presented. For this purpose, a novel Hi-Bi photonic crystal fibre was designed and fabricated. Half of the microstructured region of the photonic crystal fibre was composed by holes with large diameter, while the other half contained holes with small diameter. Due to this geometry, the fibre core was shifted from the centre and high birefringence appears in the optical fibre. The Hi-Bi photonic crystal fibre loop mirror was demonstrated as a curvature sensor. The curvature was applied for three different fibre directions for the range of 0.6 -5 metres -1 . The configuration was also characterized for temperature and longitudinal strain, showing insensitivity for these two physical parameters.