I. Introduction
Temperature sensing is especially important and indispensable as an engineering application. Normally, a thermocouple, which consists of two dissimilar metals joined together at one end, is used in temperature sensing. The disadvantages of a thermocouple, however, include poor resistance to both electromagnetic interference and corrosion. As such, with its high sensitivity, small size, and effective electromagnetic resistance, the optical fiber sensor is more applicable to temperature sensing [1]–[6]. The most common optical temperature sensing techniques include the utilization of fiber Bragg grating (FBG) [7]–[9], long period fiber grating (LPFG) [10]–[12], interferometric fiber, and photonic crystal fiber temperature sensors [13], [14]. The disadvantages of these methods include the need for expensive apparatus and that the components involved are complex and unsuitable for mass production. To overcome these disadvantages, in this study we propose a novel U-shaped, microchanneled WGM optical fiber temperature sensor that is simple, low in cost, and robust.