Temperature insensitive air-cavity Fabry-Perot gas pressure sensor based on core-offset fusion of hollow-core fibers

• Published in: Sensors and actuators. A. Physical. 2019-10, Vol.298, p.111589, Article 111589
• Main Authors: Chen, Mao-qing, Wei, He-ming, Zhao, Yong, Lei, Xiao-hua, Krishnaswamy, Sridhar
• Format: Article
• Language: English
• Subjects: Core-offset fusion; Diameters; Fabry-Perot interferometer; Fabry-Perot interferometers; Fibers; Gas pressure; Gas pressure sensor; Gases; Gold; Hollow-core fiber; Microfluidics; Optical fiber sensor; Pressure; Pressure sensors; Sensitivity; Sensors; Temperature; Thickness
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2019.111589

A temperature insensitive air-cavity Fabry-Perot Interferometer (FPI) based on core-offset fusion of hollow-core fibers (FPI-CFH) with different inner diameters was developed. This device consists of input single mode fiber (SMF), two short sections of hollow-core fibers (HCF1 and HCF2), and a gold film. The HCF1 with an inner diameter of 70 μm is used to construct air-cavity FPI, and the HCF2 with an inner diameter of 10 μm is offset spliced with HCF1 to provide a flat reflective surface of the air-cavity FPI and also function as a microfluidic channel for the gas inlet. The left end-face of HCF2 is coated with gold film to improve the light reflectivity, so that, increasing the fringe contrast of air-cavity FPI spectrum. The experimental results show that the proposed FPI-CFH sensor has the gas pressure sensitivity of 4.314 nm/MPa with a high linear response (the value of R-Square is 0.9987) when the gas pressure increases from 400 to 1000 kPa, and what's more, the proposed sensor has a negligible temperature cross-sensitivity (0.0051 nm/°C) in the range of 20 ∼ 80 °C due to the structure of all-fiber and the essential characteristics of air cavity FPI. The maximal relative error of the proposed sensor in the measurement process of gas pressure decrease is less than 1%, which illustrates the sensor has good precision and repeatability. Moreover, the proposed sensor has good stability in a long-term gas pressure testing. Therefore, the proposed FPI-CFH sensor can achieve high precision gas pressure sensing but is insensitive to the variation of temperature. [Display omitted] •A temperature insensitive air-cavity Fabry-Perot Interferometer was developed.•This device consists of input single mode fiber, two short sections of hollow-core fibers, and a gold film.•Experimental results show the proposed sensor has the gas pressure sensitivity of 4.314 nm/MPa. A temperature insensitive air-cavity Fabry-Perot Interferometer (FPI) based on core-offset fusion (FPI-CFH) of hollow-core fibers with different inner diameters was developed. This sensing structure consists of input single mode fiber (SMF), two short sections of hollow-core fibers (HCF1 and HCF2), and a gold film. The HCF1 with an inner diameter of 70 μm is used to construct air-cavity FPI, and the HCF2 with an inner diameter of 10 μm is offset spliced with HCF1 to provide a flat reflective surface of air-cavity FPI, which can increase the reflection to enhance the fringe contrast, and meanwhile the micro