Response Time of Microfiber Temperature Sensor in Liquid Environment

Response time of optical microfiber temperature sensor is investigated based on the microfiber modal interferometer (MMI). Sensitivity of -406pm/degrees C is obtained in temperature sensing, which is one order higher than those of fiber Bragg gratings (FBGs) and microfiber resonators, and response time of 13.1ms is measured, which is twice as fast as FBGs. Based on the theoretical expression of time constant in temperature sensing, dependences of response time on many factors, such as heat transfer coefficient, fiber diameter and ambient temperature are investigated, respectively. In addition, relationship of time constant and response time, dependence of response time on detection device or fiber length, and repeatability of sensor are also discussed. Results demonstrated here may afford some useful references for optical sensors used in obtaining temperature profile and transient process in seawater or analyzing temporal response of temperature sensors in other liquid surroundings.