A Novel Strain Sensor Using a Fiber Taper Cascaded With an Air Bubble Based on Fabry–Perot Interferometer

A novel optical fiber strain sensor based on a Fabry-Perot Interferometer (FPI) is proposed and experimentally demonstrated. The FPI is fabricated by splicing a single mode fiber (SMF) taper and an air micro-bubble formed by using repeated discharging on the hollow core fiber (HCF). By doing this, the sensitivity of the proposed configuration to strain is greatly increased comparing with that of other FPIs. Experimental results show that the sensitivity of the sensor to strain can reach 41.5 pm/με, 42.56 pm/με and 41.02 pm/με at the dips of 1525.9721 nm, 1646.3134 nm and 1567.1797 nm, respectively with negligible power fluctuation. And average sensitivity at three resonance peaks to temperature is 2.04 pm/°C resulting the temperature cross sensitivity of 0.0489 με/°C. In addition, the proposed sensor shows good performances in the repeatability and stability, which can be potentially used in the many fields such as medical treatment and structural health monitoring.