Low-Qwhispering gallery modes in anisotropic metamaterial shells

Abstract

Anisotropic and inhomogeneous metamaterial shells are studied in order to exploit all their resonant mode richness. These multilayer structures are based on a cylindrical distribution of radially dependent constitutive parameters including an inner void cavity. Shell, cavity, and whispering gallery modes are characterized, and special attention is paid to the latter ones. The whispering gallery modes are created at the boundary layers of the shell with the background. Energy localization is produced with highly radiative characteristics when the localization takes place at the external layer. These low-Q resonant states have frequencies that are independent of the shell thickness. However, their quality factors can be controlled by the number of layers forming the shell, which allows confining electromagnetic waves at the interface layers (internal or external), and make them suitable for the harvesting of electromagnetic energy.

Superscattering from cylindrical hyperbolic metamaterials in the visible region

“…The field distribution at 415 nm is similar to that of WGM [25], for which the electric field is localized at the outer surface and has low mode volume with the hexapolar symmetry, like the WGM at mode order q = 3. A detailed analysis is given by Chihhui Wu et al [18] for WGM in hyperbolic cavities operating in the near infrared region, and by Diaz-Rubio et al [19] for metamaterial structures operating in the GHz region. CHMMd supports WGM of symmetry q = 3 irrespective of the smaller size and possibility of enhancement of photonic density of states.…”

“…Our FDTD calculation shows that the spatial field distribution in the SSc condition is similar to a whispering gallery mode (WGM), suggesting that the WGM-like electric-field distribution leads to high scattering efficiency. WGM-like field distributions have been reported for spherical hyperbolic cavities in the infrared [18], and for a further metamaterial structure in the GHz region [19], but no study has yet been made for CHMM in the visible region. CHMMs are promising materials for SSc, and maybe applied in sensing, beam shaping, energy harvesting and other applications.…”

Control of electromagnetic energy by metamaterials

“…This method has been widely used for the study of 1D periodic media [4]. In our case due to the complexity of the RPCs some modifications have to be introduced [15]. According to Eq.…”