Ultracompact Optical Fiber Sensor for Refractive Index and High-Temperature Measurement

An ultracompact microfiber sensor head is demonstrated for refractive index and high temperature sensing. Such a device is a fiber in-line Mach-Zehnder interferometer formed by creating an inner air-cavity along a section of microfiber and exhibits a high refractive index sensitivity of ~4202 nm/refractive index unit and a good temperature sensitivity of 41 pm/°C, with excellent high-temperature sustainability up to 1100 °C.