Tunable Plasmon-Phonon Modes in Nonlinear-Graphene-hBN Heterostructures

Abstract

In this paper, the analytical expressions are derived for the study of Hybrid Surface Phonon-Plasmon-Polaritons (HSP3) in a nonlinear graphene-based structure with hexagonal Boron Nitride (hBN) layers. The numerical results show that the propagation features of HSP3 can be varied by changing the chemical potential, the relaxation time, and the nonlinear coefficient. Due to the existence of hBN layers in the proposed structure, the investigation is done in two frequency ranges: the upper and lower Reststrahlen bands. The obtained results represent that two kinds of hybrid modes propagate outside the upper and lower Reststrahlen bands which we call “higher and lower modes”. However, only one propagating mode is seen inside the upper or lower Reststrahlen band. A high value of FOM=98 is reported at the frequency of 45 THz (inside the upper Reststrahlen band) for the chemical potential of 0.35 eV. The authors believe that the analytical study done on HSP3 in this paper can help the researchers to design innovative structures such as sensors in the mid-infrared region.

Hybrid Plasma-Graphene Elliptical Structures: An Analytical Approach

“…The optical conductivity of graphene, a tunable parameter that can be adjusted by electrostatic bias (or chemical doping) and magnetostatic bias, plays the main role in the design and fabrication of graphene-based plasmonic devices in the THz frequencies [1][2][3]. This key feature makes graphene a fascinating material in the THz region in which many various devices have been presented and reported in the literature such as couplers [4][5][6], filters [7][8][9], resonators [10][11][12], circulators [13][14][15][16], waveguides [17][18][19][20][21][22][23][24][25][26], sensing [27][28][29][30][31][32], imaging [33,34], hyperbolic structures [35][36][37][38][39][40][41][42][43], and polarization converters [44]. Graphene-based waveguides have various structures such as planar [18,…”

Strong Phonon-Plasmon Coupling in Grounded Graphene-Hexagonal Boron Nitride (hBN) Heterostructures

“…This material can confine phonon polaritons in a very small area, compared to the wavelength, due to its negative permittivity in the mid-infrared region. Therefore, the hybridization of graphene with the hBN medium can produce new modes called "Coupled Plasmon-Phonon modes" [77][78][79][80]. These hybrid surface plasmon-phonon polaritons (HSP 3 ) have potential applications in the THz region such as plasmon-induced transparency [81], negative refractive [82], planar focusing [83], and topological transition [84].…”