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

Abstract:

In this Letter, 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 parallel-ized spatial mode Mach-Zehnder interferometers, both of which are involved in sensing, but possess different interfering modes. By designing a Mach-Zehnder Interferometer refractive index fiber optic sensor based on Vernier effect in air, it is demonstrated that in the low refractive index such as air environment, only the modes involved in sensing interference are affected by the environment to generate Vernier effect. In the high refractive index marine environment, both sensing interferometer and reference interferometer need to be affected by the ambient refractive index to generate Vernier effect. The simulation results indicate that the proposed novel sensing structure can amplify its sensitivity from -15428 nm/RIU to -24857 nm/RIU in the marine environment.

Key words:Marine RI measurement, Modified Vernier effect, Ultra-high sensitivity RI sensor