Group Velocity Modulation and Light Field Focusing of the Edge States in Chirped Valley Graphene Plasmonic Metamaterials

Abstract

The valley degree of freedom, like the spin degree of freedom in spintronics, is regarded as a new information carrier, promoting the emerging valley photonics. Although there exist topologically protected valley edge states which are immune to optical backscattering caused by defects and sharp edges at the inverse valley Hall phase interfaces composed of ordinary optical dielectric materials, the dispersion and the frequency range of the edge states cannot be tuned once the geometrical parameters of the materials are determined. In this paper, we propose a chirped valley graphene plasmonic metamaterial waveguide composed of the valley graphene plasmonic metamaterials (VGPMs) with regularly varying chemical potentials while keeping the geometrical parameters constant. Due to the excellent tunability of graphene, the proposed waveguide supports group velocity modulation and zero group velocity of the edge states, where the light field of different frequencies focuses at different specific locations. The proposed structures may find significant applications in the fields of slow light, micro–nano-optics, topological plasmonics, and on-chip light manipulation.

Investigation of three topological edge states in honeycomb lattices based on graphene plasmonic crystal

“…Moreover, Monfared et al have achieved the photoelectric switch operation by utilizing the unique optical properties of SPPs supported by graphene [30][31][32] Recently, Dehghan et al reported the graphene periodic lattice, which causes plasmonic modes to absorb a specific Terahertz frequency band and minimize transmission [33]. Graphene-supported SPPs have been recognized as a promising two-dimensional material for a wide range of applications such as transparent electronics, gate modulators, photocatalysts, and more [25,29,[34][35][36][37][38].…”

Advances in Plasmonics and Nanophotonics

“…This Special Issue includes five articles [1][2][3][4][5] which present some of the challenges and opportunities in the field of plasmonics and nanophotonics.…”

“…Zhuo et al [4] propose tunable valley graphene plasmonic metamaterials (VGPMs) for group velocity modulation and light field focusing of surface plasmon polariton waves. The authors further discuss a chirped VGPM waveguide composed of a supercell arrangement of VGPMs with a gradually increasing chemical potential difference.…”