Photonic crystal fiber strain sensor based on multimode/air spherical cavity structure

In this paper, a novel high-sensitivity strain sensor based on Mach–Zehnder interference is drawn up and implemented. A single-mode fiber (SMF)-splitter-PCF-combiner-SMF structure is required for the sensor. The beam splitter and beam combiner, for example, have both used MMF and an air spherical cavity, respectively. A strain sensor with easy operation, low cost, excellent repeatability, and high sensitivity was developed using the sensing structure. The experimental results show that the strain sensor has a maximum sensitivity of −8.15 pm/μɛ. When the symmetric structure of the air spherical cavity is utilized, the strain sensor has a maximum sensitivity of −8.15 pm/μɛ. The device has the benefits of high sensitivity, small size, and good repeatability, making it a possible application in strain shift measurement.