Arc-Discharge Realized Optical Microfiber Couplers With Ultralow Temperature Coefficient for Sensing Applications

Optical microfiber couplers (OMCs) with simple structure, low loss, and high sensitivity have been broadly involved in physicochemical fiber sensing applications. Until now, the fabrication of OMCs using arc discharge as a fast, clean, and low-cost method has not been explored. In this study, an arc-discharge fiber heating and pulling process for OMC manufacturing is presented and the characteristics of the arc-induced structures are investigated. It is shown that, in addition to high spectral visibility and refractive index (RI) sensitivity, importantly, the arc-induced OMCs exhibit ultralow temperature dependency of less than 1.9 pm/°C, over the wide testing range of 15 °C to 315 °C. Finally, an exact theoretical explanation is presented for the observed different temperature coefficients using analytical expressions and full-wave simulations based on the modal analysis of OMCs. Thus, the introduced arc-discharge technique and the resultant OMCs with ultralow temperature dependency could be useful for real-world applications of microfiber (MF) couplers.