Temperature sensitivity characteristics of HCPCF-based Fabry-Perot interferometer

Optical fiber Fabry-Perot interferometers (FPIs) formed by splicing hollow-core photonic crystal fiber (HCPCF) to single mode fiber (SMF) are proposed, and the temperature sensitivity characteristics are investigated theoretically and experimentally. Interestingly, the HCPCF-based FPIs with different structures have different responses to temperature: the FPI formed by a short HCPCF and a long SMF pigtail has a linear wavelength response to temperature with a sensitivity of 9.17 pm/°C and its fringe contrast is nearly temperature-insensitive; while the FPI with a long HCPCF and a short SMF cap is temperature-insensitive both for wavelength and fringe contrast. Refractive index (RI) test results show good linear response based on fringe contrast. Thus the HCPCF-based FPI sensors can be applied to temperature detection and RI measurement simultaneously with negligible cross-sensitivity or completely temperature-independent measurement by using different structures. Due to the advantages of small size, robust structure, easy fabrication, low cost and good fringe visibility, the HCPCF-based FPI sensors have broad application prospect in the fields of biology, chemistry and so on.