A Highly Sensitive Curvature and Rotation Angle Sensor Based on Asymmetric Hollow-Core Anti-Resonant Fiber

We report a high-sensitivity fiber sensor based on homemade asymmetric hollow-core anti-resonant fiber (HC-ARF), which can realize both curvature and rotation angle measurement. The sensor makes use of mode coupling in the asymmetric HC-ARF without forming an interferometer or any fiber processing, which makes the sensor structure more compact and reliable. To the best of our knowledge, it is the first time to realize the curvature and rotation angle sensing using the principle of mode coupling in an HC-ARF. Experiment results show that the sensitivities of curvature and rotation angle are as high as 35.8 nm/m(-1) and 1 nm/degrees, respectively. Simulation results show that the curvature and rotation angle sensitivity can be further improved to 63.4 nm/m(-1) and 10 nm/degrees with the optimization of fiber structure parameters. The results reveal that the utilization of mode coupling in the asymmetric HC-ARF can be regarded as a new promising path for the measurement of angle-resolved curvature.