Temperature and refractive index sensing characteristics of an MZI-based multimode fiber–dispersion compensation fiber–multimode fiber structure

We proposed an optical fiber sensor with simple multimode fiber (MMF)–dispersion compensation fiber (DCF)–multimode fiber structure based on Mach–Zehnder Interferometer (MZI) and researched its temperature and refractive index (RI) sensing characteristics. The sensing principle is based on the interference between core and cladding modes of DCF due to the large core diameter mismatch. Spectral analyses demonstrate that the transmission spectrum is mainly formed by the interference between the dominant excited cladding mode and core modes. The experimental results show that the proposed sensor has high temperature sensitivity of 0.118 nm/°C in the range of 20–250 °C and RI sensitivity of 66.32 nm/RIU within the linear sensing range of 1.33–1.39 RIU. Therefore, the characteristics of compact size, low cost, easy fabrication, high sensitivities, and good anti-interference ability make this sensor have extensive application prospects.

► We report a Mach–Zehnder Interferometer with MMF–DCF–MMF structure. ► The interference spectrum is mainly formed by the dominant excited cladding mode (LP01) and core mode. ► The proposed sensor has satisfactorily high temperature sensitivity of 0.118 nm/°C and RI sensitivity of 66.32 nm/RIU. ► The proposed sensor has potential ability of high-temperature measuring.