Optical fiber Fabry-Perot silica-microprobe for a gas pressure sensor

An all-fiber Fabry-Perot microprobe gas pressure sensor based on the femtosecond (fs) laser micromachining technology is proposed and demonstrated. The protruding-shaped silica-microprobe is spliced on the tip of the single mode fiber (SMF), and the gas microcavity is fabricated by the fs laser to form the Fabry-Perot interferometer (FPI), and the machining accuracy of the gas microcavity is better than 2 μm. The length of silicon-microprobe is less than 150 μm and its diameter is less than 30 μm, and the length of gas microcavity in microprobe is about 52 μm. The third reflective surface is formed at the junction between the microprobe and the SMF, the vernier effect can be cleverly utilized to improve the sensitivity of gas pressure. The experiment results indicate that the microprobe FPI gas pressure sensor has a sensitivity of 16.3536 nm/MPa with the increase of gas pressure, and a sensitivity of temperature is only 0.0043 nm/°C from 30 °C to 100 °C. The gas pressure sensor has the advantages of small size, high gas pressure sensitivity and low cross-sensitivity of temperature, and is expected to be applied in the special field, such as detection of gas pressure in alveoli.