A Fiber Strain Sensor With High Resolution and Large Measurement Scale

A fiber strain sensor which is formed by cascading an optical microfiber coupler and a Sagnac loop is proposed and studied. The optical microfiber coupler, and the Mach-Zehnder interferometer formed between the optical microfiber coupler and the Sagnac loop can serve as different strain sensing elements, used for different types of strain measurement. The optical microfiber coupler is mainly responsible for precisely sensing small scale strain variations, and the Mach-Zehnder interferometer focuses on measuring strain in large operation range. The operating principle of this sensor is theoretically analyzed, and the experimental sensing spectra are in consistent with the simulated results.