Polymer-Capped Fiber Fabry-Perot Interferometer for Large Range Displacement Sensing

Attaching sensitive materials to the tip of an optical fiber has been a successful strategy, extensively used to develop selective and highly sensitive sensors. In this work, we demonstrate tha,t it is possible to enlarge up to 9 times the displacement dynamic range of an extrinsic fiber Fabry-Perot interferometer (EFPI) by adding a semi-spherical polymer cap to the end-face of a single-mode fiber (SMF) FC/PC connector. Using a single modified EFPI and taking advantage of the Vernier effect displacement measurements with subnanometer resolution, it is demonstrated.