Parallel Double-FPIs Temperature Sensor Based on Suspended-Core Microstructured Optical Fiber

A configuration based on a parallel double Fabry-Perot interferometers (FPIs) is proposed and experimentally demonstrated to enhance the temperature sensitivity by Vernier-effect. Two separated FPIs constructed by suspendedcore microstructured optical fiber (SCMF) are connected by a 3-dB coupler to form a parallel structure. FPI-2 is used for temperature sensing, while FPI-1 as a reference. With the temperature increasing from 40 °C to 220 °C, both the fine interference fringes and envelope have a linear redshift. This parallel doubleFPIs configuration shows an enhanced temperature sensitivity of 153.8 pm/°C with an amplification factor M = 14.6. Moreover, since the free reference FPI-1 is away from the temperature sensing environment, this simple and novel parallel double-FPIs configuration provides good reversibility and stability during the heating and cooling processes.