Optimizing scanning trajectory for laser nanoprinting of micro-optical Fabry-Perot interferometer integrated on single-mode fiber end-face for gas flow sensing

Here, we demonstrate a high performance fiber-tip gas flow sensor by integrating an optical Fabry-Perot interferometers onto single-mode fiber end-face with all-in-one 3D laser nanoprinting technique. The device comprises of a suspended disk-shaped reflection polymer diaphragm, along with eight folding-shaped supporting pillars. The diaphragm was fabricated with a diameter of 50 mu m and a thickness of 5 mu m, while the eight foldingshaped supporting pillars were incorporated to increase the elasticity of cavity length, varying from 10 mu m to 25 mu m. To optimize the reflectivity and modulation depth of polymer mirror, we adjusted the scanning trajectory and achieved optimal result. The all-in-one printing method increased the stability of the Fabry-Perot interferometer, resulting in high fringe contrast at spectrum. When utilized as a gas flow sensor, the fiber-tip Fabry-Perot interferometer with a cavity length of 25 mu m exhibited a stable linear response to various gas flow values in the range of 80-120 mL/min. It demonstrated a sensitivity of 60 pm/mL/min with the position of 0.5 mm away from the gas outlet. The proposed method offers great flexibility and potential for preparing optical fiber end-face devices in fiber sensing, imaging, detection, and other applications.