High-Sensitivity Salinity Sensor by Using Core-Offset Based Fiber MZI

A salinity sensor is proposed based on an optical fiber Mach-Zehnder interferometer (MZI) fabricated by using a short section of single-mode fiber (SMF) with two large core-offset fusion splicing structures. The depth of each core-offset and the length between the two core-offsets are 62.6 μm and 350 μm, respectively. Salinity measurement with sensitivity of −2.536 nm/‰ is achieved within a range between 0 to 40 ‰.