Research on the preparation of multi-core photonic crystal fiber and the curvature sensing performance of three-core photonic crystal fiber

Two- and three-core photonic crystal fibers are prepared by using the same photonic crystal fiber preform structure. Not only the fiber diameter is reduced to standard size of 125μm, but also the core diameter is reduced to below 4μm. A curvature and temperature sensing system is built, and the curvature and temperature sensing performance of the three-core optical fiber is tested. When the length of three-core optical fiber is 150 mm, the measured curvature sensitivity is −7.27069 nm/m−1 in the range of 0 to 0.990 m−1, and the temperature sensitivity is −34 pm/∘C during the temperature reduction from 75 to 45 °C. When the length of three-core photonic crystal fiber is 68 mm, the curvature sensitivity and temperature sensitivity are 2.42419 nm/m−1 and −7 pm/∘C, respectively. In a small range of temperature, the sensor is insensitive to temperature, and the cross interference of temperature to curvature is very small.