Cladding mode characteristics simulation of an excessively tilted fiber grating coated with gold nanoshells

The cladding mode characteristics simulation of an excessively tilted fiber grating (ExTFG) coated with gold nanoshells was conducted in this study. First, the effective refractive indices of the core and cladding mode before coating were obtained by solving the eigenvalue equation of the three-layer waveguide structure, and the coupling characteristics were briefly analyzed. Then HE(1,)m and EH1, m modes were selected as the research objects, and the spectral characteristics of ExTFG coated with gold nanoshells were simulated by the finite element method. The simulated refractive index sensitivity of HE1,29 and EH1,29 modes is 160.16 and 185.03 nm/RIU, respectively. Compared with the non-localized surface plasmon resonance (LSPR) effect, it increased by 10.76 nm/RIU (7.2%) and 19.53 nm/RIU (11.8%), respectively. Thus, the LSPR effect was verified to be beneficial to improve the refractive index sensitivity of ExTFG. (C) 2022 Optica Publishing Group

Automated summary

This study simulated the cladding mode characteristics of an excessively tilted fiber grating coated with gold nanoshells. It was found that the localized surface plasmon resonance effect can enhance the refractive index sensitivity of the fiber grating.