Highly Sensitive Fiber Optic Curvature Sensor

Abstract

A curvature fiber optic sensor using a two-core fiber (TCF) is proposed and demonstrated. The TCF, which is designed to allow coupling between the cores, acts as a directional coupler and thus offers sinusoidal spectral response. The sensor is fabricated by splicing a 50 mm-long section of TCF between two SMFs. When the fiber is bent, the coupling coefficient between the cores is modified mainly due to stress-optic effect resulting in a blue shift of the sinusoidal spectral response and then allowing performing measurement of curvature. The sensor exhibits linear response in the range from 0 to 0.27 m−1 with sensitivity of −137.87 nm/m−1.