Intensity Modulated Gas RI Sensor Based on Inornate Antiresonant Hollow-Core Fiber With Ultrahigh Sensitivity

A gas refractive index (RI) sensor based on an inornate antiresonant hollow-core fiber (HCF) was theoretically analyzed and experimentally demonstrated. The transmission spectra evolution of the proposed sensor and the resonance intensity variations to the surrounding gas RI were simulated. Theoretical analysis found that the intensity sensitivity of inornate HCF is higher than that of coated HCF. In the experiment, a sensor with a 5 mm-long HCF provided exceptional sensitivity—as high as 2236.1 dB/RIU. The sensitivity was enhanced by improving the resonance intensity of the inornate HCF, which could be further improved by increasing the HCF length. In addition, temperature sensing was performed to resolve the temperature cross-sensitivity issue using a wavelength interrogation method. The proposed RI sensor exhibited the advantages of easily manufactured and with ultrahigh sensitivity.