Long-Period Gratings in Perfluorinated Plastic Optical Fibers Implemented by Micro Dry-Etching Technique

This paper reports the first implementation of long-period gratings (LPGs) on perfluorinated plastic optical fibers (PF-POFs) using a micro dry etching technology, which is more controllable and potentially mass-processable than conventional laser irradiation techniques. Micrometer-scale periodic structures were fabricated on PF-POFs by a reactive ion etching processing with a silicon shadow mask, and the frequency characteristics specific to LPGs are experimentally confirmed by inducing refractive index modulation due to internal stress distribution. These findings highlight the potential for further precise control of the properties of LPG-based PF-POF sensors, as well as their wide use in applications.