Simulations of ultra-high sensitivity RI sensor in triple-core fiber with modified Vernier effect:Application in marine RI measurement

Abstract:

We proposed an ultra-high sensitivity triple-core fiber refractive index (RI) sensor with a modified Vernier effect for marine RI measurement and demonstrated it by numerical simulation. This sensor composes a pair of parallelized spatial mode Mach-Zehnder interferometers (MZIs), both of which are involved in sensing, but possess different interfering modes. By designing an MZI RI fiber optic sensor based on Vernier effect in air, it is demonstrated that in the low RI such as air environment, only the modes involved in sensing interference are affected by the environment to generate Vernier effect. In the high RI marine environment, both sensing interferometer and reference interferometer need to be affected by the ambient RI to generate Vernier effect. The simulation results indicate that the proposed novel sensing structure can amplify its sensitivity from −15 428 nm/RIU to −24 857 nm/RIU in the marine environment.