An optical fiber curvature sensor based on photonic crystal fiber modal interferometer

An optical fiber curvature sensor based on photonic crystal fiber (PCF) modal interferometer is demonstrated. The sensor is fabricated by a length of 5 cm PCF which is spliced between two single mode fibers (SMF). The result shows that this sensor is sensitive to curvature with a sensitivity coefficient of 4.451 nm m−1 in the range of 0–2.14 m−1, and the resolution of the curvature measurement is about 4.4 × 10−3 m−1. The temperature sensitivity of the sensor is only 7.78 pm/°C, so it is more suitable for curvature measuring.