High Sensitivity Temperature Sensing Based on Intermodal Coupling of a Tapered Multicore Fiber

A high-sensitivity fiber-optic temperature sensor consisting of a cascaded structure of multimode fiber (MMF), tapered seven-core fiber (TSCF) and multimode fiber (MMF) is proposed. The characteristics of the MMF-TSCF-MMF structure, referred to as the MTSCM, are analyzed and simulated using the beam propagation method (BPM) both before and after the seven-core fiber (SCF) is tapered. Simulations indicate a fiber Mach-Zehnder interferometer (MZI) is formed within the structure. Both simulation and experimental results demonstrate that the MTSCM structure exhibits a stronger evanescent field and more surrounding core and cladding modes. A sensitivity of −760 pm/°C is achieved by using MTSCM structure sensor in temperature measurement, significantly higher than that of the MSCM structure sensor. The proposed sensor holds a great potential for marine environment detection.