Side-perforated hollow-core fiber based ultra-sensitive Fabry–Perot interferometric gas pressure detector

Gas pressure monitoring devices deployed in industrial production and scientific testing scenarios simultaneously demand ultra-high detection sensitivity, compact packaging and stable signal response performance. Nevertheless, most existing fiber-optic pressure transducers fail to balance high measurement sensitivity and simple miniature structure effectively. This research designs and experimentally validates a novel high-sensitivity pressure sensing device built upon Fabry–Perot interferometer (FPI) architecture. The sensor is constructed by drilling a micro-hole on the cladding sidewall of hollow-core fiber (HCF), followed by forming an ultraviolet cured polymer thin film inside the fiber cavity to establish a tiny FP interference chamber directly communicating with external gas environment. The proposed structure couples two pressure response mechanisms: gas refractive index variation induced by air pressure fluctuation and elastic deformation of the polymer diaphragm, which jointly amplify the optical path difference shift of interference spectra. Experimental characterization indicates the fabricated prototype achieves a gas pressure response sensitivity of 0.553 nm/kPa with a linear fitting coefficient up to 0.99. Besides, the sensor maintains weak temperature interference, with temperature cross-sensitivity measured as −0.13 kPa/°C. Benefiting from its superior sensitivity, miniaturized volume, low fabrication difficulty and easily accessible raw optical materials, the proposed fiber-optic transducer offers a brand-new monitoring scheme for micro-pressure signal tracking and biochemical microenvironment pressure detection.