Hollow-core Fiber Refractive Index Sensor with High Sensitivity and Large Dynamic Range Based on a Multiple Mode Transmission Mechanism

To balance the tradeoff between the high sensitivity and large dynamic range, a fiber optic refractive index sensor based on the anti-resonant reflecting optical waveguide (ARROW) and mode interference has been proposed and experimentally demonstrated. A double-layered ARROW was formed in a hollow core fiber, and a mode interference was also generated in the fiber skeleton using offset splicing. The proposed fiber optic refractive index sensor possesses both high sensitivity and large dynamic range due to the different refractive index sensitivities of the ARROW and mode interference. The experimental results show that a high refractive index sensitivity of 19014.4 nm/RIU for mode interference and a large dynamic range from 0.04 RIU for ARROW can be achieved simultaneously. The proposed fiber optic refractive index sensor can be used in chemical and biological applications.