Fabrication and Characterization of Microbent Inline Microfiber Interferometer for Compact Temperature and Current Sensing Applications

A new microbent in-line microfiber interferometer (MI-MI) is proposed and demonstrated as a compact temperature and current sensor. The MI-MI is capable of generating interference fringes with a high extinction ratio of about 12.0 dB and a free spectral range of 1.9 nm at a wavelength of 1545 nm. When employed as a temperature sensor, a copper wire carrying a direct current is placed against the MI-MI sensor, and the interference fringes of the MI-MI sensor shifts toward the longer wavelength as the heat generated by the copper wire increases. As the temperature increase corresponds linearly to the current, thus the measurement of the current can be extrapolated as well. The sensor has a temperature responsivity of 33.0 pm/°C with a linearity of more than 0.97 as well as a current responsitivity of 1.46 °C/A
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, and has significant potential for application as a health and warning sensor for electricity generation and distribution grids.