Refractive index sensor based on θ-shaped microfiber resonator and Vernier effect

A compact refractive index (RI) sensing probe with controllable sensitivities based on a θ-shaped microfiber resonator and Vernier effect is reported. By cascading the θ-shaped microfiber resonator with a fiber Fabry-Perot interferometer, Vernier effect is generated to enhance the RI sensitivity. Both theoretical analyses and experimental results demonstrate that the RI sensitivity can be tuned by changing the cavity length of the θ-shaped microfiber resonator. The RI sensitivity is widely tuned from 311.77nm/RIU to 2460.07nm/RIU in the experiment. The θ-shaped microfiber resonator and the proposed method of generating Vernier effect could find important applications in optical fiber sensing field.MOE (Min. of Education, S’pore)Published versio