A High-Sensitivity Temperature Sensor Based on a Liquid Cladding Tapered Microfiber

Abstract

A high-sensitivity interferometric optical microfiber sensor based on liquid cladding is proposed to detect liquid samples temperatures in special environments. The sensor is manufactured by arc discharge and flame-brushing technology and is encapsulated in a capillary tube and covered with deionized water. The sensor is more susceptible to the influence of the external environment due to the strong evanescent field on the tapered fiber surface. High-sensitivity measurement near room temperature is important, which can be used for effective diagnosis and treatment of local temperature of biological tissues in the field of biosensing. Compared with the silica material, the sensor based on liquid encapsulation has a larger thermo-optical coefficient, and the difference between the thermo-optic coefficient of water and the optical fiber is greater. The results show that with increasing ambient temperature, the wavelength of the transmission spectrum shifts towards shorter wavelengths. The device without liquid packaging has a temperature sensitivity of −57 pm/°C, and the liquid-encapsulated microfiber can reach −415 pm/°C ranging from 30-50 °C, which is 7+ times higher than the former. In addition to improving the temperature sensitivity of the sensor, the water cladding can protect the microfiber from damage. This sensor can be used as a basic sensing unit in remote and intelligent optical fiber sensor networks with great application potential in marine environment monitoring, biomedicine diagnosis and chemical reaction research.