High-Temperature sensor based on peanut flat-end reflection structure

A high-temperature sensor based on a peanut flat-end reflection structure is demonstrated. The sensor can be simply fabricated by splicing the spherical end-faces of two segments of single-mode fibers and then cleaving one other end as a flat reflect surface. The proposed structure works as a reflected interferometer. When the ambient temperature changes, the resonant dip wavelength of the interferometer will shift due to the linear expansion or contraction and the thermo-optic effect. As a result, the temperature measurement can be achieved by monitoring the resonant dip wavelength of the interferometer. Experimental results show that the proposed sensor probe based on the peanut flat-end reflection structure works well and it can measure the temperature range from 100 °C to 900 °C with the sensitivity of 0.098 nm/ °C with R2  =  0.988. When temperature ranges from 400 °C to 900 °C, the sensitivity of 0.11 nm/ °C can be achieved with R2 = 0.9995. Due to its compact and simple configuration, the proposed sensor is a good high temperature sensor probe.