Long-term stability improvement of Brillouin measurement in plastic optical fibers by fresnel suppression using amorphous fluoropolymer

For Brillouin-sensing applications, we develop a method of mitigating the Fresnel reflection at the end of perfluorinated plastic optical fibers by covering there with amorphous fluoropolymer (CYTOP; material of the fiber core) dissolved in volatile solvent. Even after the solvent evaporates, the CYTOP layer remains, leading to long-lasting Fresnel reduction.