Diaphragm-free gas-pressure sensor probe based on hollow-core photonic bandgap fiber

A diaphragm-free probe-type gas-pressure sensor is pro posed and experimentally demonstrated based on a hollow-core photonic bandgap fiber (HC-PBF) with a quartz capillary. The section of the HC-PBF acts as a Fabry-Perot cavity, and the quartz capillary acts as a microfluidic channel for a gas inlet. An inner diameter of the quartz capillary (similar to 2 pm) smaller than the HC-PBF (similar to 10.9 pm) ensures a mirror reflection and a microfluidic channel simultaneously. The sensor probe has a minimal size (similar to 125 mu m) and can function at gas pressures as high as 8 MPa. A higher pressure test is limited by our gas-pressure generation devices. Excellent stability of the sensor is observed in a long timescale, and repeatability of the sensor is confirmed by tests of six different samples. Compared with conventional optical fiber gas-pressure sensors, the proposed sensor involves a simple fabrication process and can acquire probe measurements with high sensitivity (similar to 4.17 nm/MPa), excellent linearity (0.9999), fast response, and no hysteresis. The proposed sensor can also function at temperatures as high as 800 degrees C, which is beneficial for high pressure measurements in extreme conditions. Moreover, the fast response of the sensor is attractive for dynamic pressure measurements, which needs further study and characterization. (C) 2018 Optical Society of America