Fiber curvature sensor based on refractive effect of tilted splicing surface

A bending sensor based on single-mode fiber spliced with hollow-core fiber at a small inclination angle is proposed. Additionally, an index matching layer is applied to structure for eliminate the interference of anti-resonance reflections on spectrum. Compared to vertical splicing, the slant shortens the peak-forming distance of structure by adjusting the angle of refracted light. Furthermore, the curvature sensitivity of sensor is affected by bending direction, and the larger the tilt angle the greater the sensitivity difference. The structure has a maximum sensitivity of 32.5 nm/m-1 and also has a compact length and high tensile strength. In summary, oblique splicing provides a new scheme for parameter optimization of fiber bending sensors.