Improved optical fiber Mach-Zehnder high-sensitivity refractive index sensor

Abstract A simple, highly sensitive, and all-fiber four-tapered Mach-Zehnder interferometer (FTMZI) refractive index (RI) sensor was proposed and experimentally demonstrated, which was fabricated by simply and repeatedly discharging a small section of single-mode fiber (SMF). Multiple tapers excite the high-order mode of the fiber cladding, making it sensitive to changes of external RI. The sensor shows a high sensitivity of 987.9 nm/RIU when the external RI changes from 1.330 to 1.346. Furthermore, the thermal response experimental results show that the temperature sensitivity of the sensor is 19.2 pm/°C, and the temperature crosstalk is only 0.00002 RIU/°C, making it a suitable candidate for temperature independent RI sensing.