Polarized optical properties of hollowed-out 2D-gold-nanosheets studied using FDTD simulations

Hollowed-out gold-nanosheets (HoGNSs) are one of the special two-dimensional single-crystals on which their bodies (the body of HoGNS, abbreviated as NS-body) contain one or more hollow defects. There are many shape combinations of the outside NS-body and inside hollow-cavity [e.g., Triangle–Triangle (T–T), Hexagon–Triangle (H–T), etc.]. HoGNSs, especially the large-scaled ones, were found to have potential applications in remote surface-enhanced Raman scattering. However, owing to the anisotropy of the hollowed-out structure, the optical properties of different HoGNSs are closely related to the polarization of the incident wave and also to the relative orientations of the paired outer-NS-body and inner-hollow-cavity. Thus, the polarized optical properties of HoGNSs have been studied using finite-difference time-domain (FDTD) simulations. The local electric field near the vertex of the hollow-cavity will be affected by the size, the relative orientation, and the number of sides of the outer-NS-body. There are two different kinds of mechanisms for surface plasmon resonance,-that is, the excitation by the evanescent wave mainly concentrated on the surface of the outer-NS-body and the total internal reflection of the trapped wave between every two adjacent sides of the inner-hollow-cavity. The results have shown that there are strong interactions between the outer-NS-body and inner-hollow-cavity (including their size-, structure-, and orientation-interactions), which suggested that the optical properties of 2D-GNSs were influenced by many parameters but the best and optimum could be derived from FDTD simulations.