Extraordinary Optical Transmission by Hybrid Phonon–Plasmon Polaritons Using hBN Embedded in Plasmonic Nanoslits

Abstract

Hexagonal boron nitride (hBN) exhibits natural hyperbolic dispersion in the infrared (IR) wavelength spectrum. In particular, the hybridization of its hyperbolic phonon polaritons (HPPs) and surface plasmon resonances (SPRs) induced by metallic nanostructures is expected to serve as a new platform for novel light manipulation. In this study, the transmission properties of embedded hBN in metallic one-dimensional (1D) nanoslits were theoretically investigated using a rigorous coupled wave analysis method. Extraordinary optical transmission (EOT) was observed in the type-II Reststrahlen band, which was attributed to the hybridization of HPPs in hBN and SPRs in 1D nanoslits. The calculated electric field distributions indicated that the unique Fabry–Pérot-like resonance was induced by the hybridization of HPPs and SPRs in an embedded hBN cavity. The trajectory of the confined light was a zigzag owing to the hyperbolicity of hBN, and its resonance number depended primarily on the aspect ratio of the 1D nanoslit. Such an EOT is also independent of the slit width and incident angle of light. These findings can not only assist in the development of improved strategies for the extreme confinement of IR light but may also be applied to ultrathin optical filters, advanced photodetectors, and optical devices.

Phonon Polaritons Assisted Extraordinary Transmission in α-MoO-Silver Grating and Its Application in Switching

“…The aspect ratio used in numerical simulations is compared with the theoretically calculated values to verify that the zig-zag behaviour is not just the diffraction from the grating edges. The order of resonance mode (number of zigzags) and propagation angle (β) shows dependence on the AR of the structure and is related as [27]:…”

“…There have been several studies of metallic gratings coupled with other 2-D materials especially graphene for enhancement and tunability of EOT response [25], [26]. Also, recently, hBN coupled with grating made of silver has been reported where the EOT effect in its RB-2 (type-II hyperbolic region) is studied for various structural parameters [27]. But this EOT response is not tunable and cannot exhibit dual range of operation due to in-plane isotropic behavior of hBN.…”