Temperature-insenstive curvature sensor using a Hi-Bi photonic crystal fiber based Sagnac loop interferometer

We propose and demonstrate a Sagnac loop interferometer composed of a novel Hi-Bi photonic crystal fiber with two large air holes in the outer cladding region as a curvature sensor. It has been shown that it has an insensitivity to temperature and a curvature sensitivity of 0.159 nm/m −1 when the fiber is bent in the slow axis.