Ultrasensitive gas pressure sensor based on two parallel Fabry-Perot interferometers and enhanced Vernier effect

An ultra-high sensitivity optical fiber gas pressure sensor based on enhanced Vernier effect is proposed. The sensor consists of FPI1 and FPI2 in parallel. FPI1 is composed of single mode fiber, quartz capillary and polydimethylsiloxane film. FPI2 consists of single mode fiber, large inner-diameter capillary, and small inner-diameter capillary. Because FPI1 and FPI2 have different sensing mechanisms for gas pressure, the interference fringes of FPI1 and FPI2 drift in the opposite direction with the change of ambient gas pressure. When FPI1 and FPI2 with a similar free spectral range are connected in parallel, an enhanced Vernier effect is generated. Compared with the traditional Vernier effect gas pressure sensor, the enhanced Vernier effect gas pressure sensor realizes ultra-high sensitivity gas pressure measurement without increasing the difficulty of sensor manufacturing. The sensitivity of the enhanced Vernier effect gas pressure sensor is as high as 283.32 nm/MPa, which is about 1.7 times that of the traditional Vernier effect barometric sensor (170.03 nm/MPa). In addition, the sensor has the advantages of good repeatability and stability, low cost, small temperature cross-sensitivity and easy manufacture. The sensor structure designed provides a new design idea and scheme for the ultra-high sensitivity optical fiber gas pressure sensor.