Axial Strain Sensor Based on Microfiber Couplers Operating at the Dispersion Turning Point

A novel axial strain sensor based on an optical microfiber coupler (OMC) operating at the dispersion turning point (DTP) was designed to realize high-sensitivity measurements of axial strain. First, we explain the measurement principle of axial strain sensors based on microfiber couplers. Then, we calculate the measurements, with the theoretical calculations showing that the sensor has high sensitivity when the effective refractive index (ERI) difference between the odd and even modes in the coupling region of the OMC is equal to zero. Finally, we carried out axial tensile experiments on the OMC. The results show that the OMC has the highest axial strain sensitivity when it operates at the DTP. The maximum sensitivity is 166.9 pm/ $\mu \varepsilon $ , with a linear range of 0- $400 ~\mu \varepsilon $ . The sensor is highly sensitive to axial strains and has a simple structure. It has broad application prospects in the measurement of mechanical quantities such as strain, acceleration and vibration.