LAUSR

Abstract In this paper, a high sensitive seawater temperature sensor fabricated by splicing a piece of no-core fiber (NCF) with coating between single mode fibers (SMF) was demonstrated. Part of the incident light in SMF transmitted to the coating of NCF and reflected to the cladding at the boundary of coating-air, which excited multimode interference (MMI) and clear interference curve can be seen in the transmission spectrum. The characteristic wavelength exhibits a linear temperature response with maximum sensitivity about −4.677 nm/°C in the range of −5 to 45 °C. In addition, different order interference dips with similar sensitivity disappear and generate when temperature changes, and the order can be determined by cascading a fiber Bragg grating (FBG). Hence, such a coated-NCF sensor can be used for wide range and high precision seawater temperature measurement.