It has been demonstrated that circular dichroism (CD) signals from chiral molecules can be boosted by plasmonic nanostructures inducing strong local electromagnetic fields. To optimize nanostructures to improve CD enhancement, numerical simulations such as the finite element method (FEM) have been widely adopted. However, FEM calculations for CD have been frequently hampered by unwanted numerical artifacts due to improperly discretizing problem spaces. Here, we introduce a new meshing rule for FEM that provides CD simulations with superior numerical accuracy. We show that unwanted numerical artifacts can be suppressed by implementing the mirror-symmetric mesh configuration that generates identical numerical artifacts in the two-opposite circularly polarized waves, which cancel each other out in the final CD result. By applying our meshing scheme, we demonstrate a nanostructure/chiral molecule coupled system from which the CD signal is significantly enhanced. Since our meshing scheme addresses the previously unresolved issue of discriminating between very small CD signals and numerical errors, it can be directly applied to numerical simulations featuring natural chiral molecules which have intrinsically weak chiroptical responses.
Bibliographical noteFunding Information:
This work was supported by the Center for Advanced MetaMaterials (CAMM), funded by the Ministry of Science, ICT and Future Planning as Global Frontier Project (CAMM-2014M3A6B3063710). J. H. Kang was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2018R1C1B6009007). SeokJae Yoo was supported by Basic Science Research Program through the NRF funded by the Ministry of Education (2017R1A6A3A11034238).
© 2018 The Author(s).
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