An Optical Fiber Sensor Based on Lateral-Offset Spliced Seven-Core Fiber for Bending and Stretching Strain Measurement

We demonstrate a fiber-optic strain sensor based on a seven-core fiber (7-CF) for accurate extrusion bending and tensile strain sensing. The sensor structure we designed is the 7-CF spliced to a piece of multimode fiber on each side with a lateral core-offset and then conventionally fused to single mode optical fiber as the input and output ports. The experimental results indicate that the optimal curvature sensitivity of the sensor is achieved 25.96 nm/m
^-1
, and the sensitivity of the tensile strain is 0.094 nm/με, which allows us to monitor bending and stretching strain respectively with high precision by the simple, low-cost, and effective sensor.