Cylinder-type fiber-optic Vernier probe based on cascaded Fabry-Perot interferometers with a controlled FSR ratio

摘要

We designed a cylinder-type fiber-optic Vernier probe based on cascaded Fabry-Perot interferometers (FPIs) in this paper. It is fabricated by inserting a short single-mode fiber (SMF) column into a large-aperture hollow-core fiber (LA-HCF) with an internal diameter of 150 mu m, which structures a length adjusted air microcavity with the lead-in SMF inserted into the LA-HCF from the other end. The length of the SMF column is 537.9 mu m. By adjusting the distance between the SMF column and the lead-in SMF, the spectral change is displayed intuitively, and the Vernier spectra are recorded and analyzed. In sensitivity analysis, the probe is encapsulated in the medical needle by ultraviolet glue as a small body thermometer when the length of the air microcavity is 715.5 mu m. The experiment shows that the sensitivity of the Vernier envelope is 12.55 times higher than that of the high-frequency comb. This design can effectively reduce the preparation difficulty of the optical fiber Vernier sensor based on cascaded FPIs, and can expand the applied fields by using different fibers and materials. (C) 2018 Optical Society of America