Confined transverse-electric graphene plasmons in negative refractive-index systems

Abstract

Transverse electric graphene plasmons are generally weakly confined in the direction perpendicular to the graphene plane. They are featured by a skin depth δ, namely the penetration depth of their evanescent fields into the surrounding environment, much larger than the wavelength λ in free space (e.g., δ > 10λ). The weak spatial confinement of transverse electric graphene plasmons is now the key drawback that limits their practical applications. Here we report the skin depth of TE graphene plasmons can be largely decreased down to the subwavelength scale (e.g., δ < λ/10) in negative refractive-index environments. The underlying mechanism originates from the different existence conditions for TE graphene plasmons in negative and positive refractive-index environments. To be specific, their existence in negative (positive) refractive-index environments requires Im(σ s) > 0 (Im(σ s) < 0) and lies in the frequency range of ħω/μ c < 1.667 (ħω/μ c > 1.667), where σ s and μ c are the surface conductivity and chemical potential of monolayer graphene, respectively.

Recent advances of transition radiation: Fundamentals and applications

“…Actually, he preferred the explanation of transition radiation, after the mathematical analysis of the denominator in the expression of transition radiation near the peak of Ferrell radiation [98]. Due to the recent advances in plasmonics [99][100][101][102][103][104][105], it is now acknowledged that the radiative SPO is essentially a leaky mode, denoted as the Ferrell mode [84,97,98,106]. In 2022, the Ferrell radiation was re-investigated in the time domain and was found able to occur far beyond the formation time, since it is supported by a long tail of bulk plasmons following the electron's trajectory deep into the plasmonic medium [107].…”

Collective magnetic excitations in AA- and AB-stacked graphene bilayers

“…These excitations are closely pinned to the light cone and thus weakly confined, which allows for their detection in the Otto configuration [16,17]. Negative refractive index environments can help to enhance their confinement [18,19], and magnetically biased graphene-ferrite structures give rise to nonreciprocal plasmons [20]. Also, in AB-stacked bilayer graphene the transverse modes are considerably more confined than in its monolayer counterpart [21].…”

Mid-infrared photodetector based on 2D material metamaterial with negative index properties for a wide range of angles near vertical illumination

“…The negative index materials exhibit the superlensing properties and, thus, enable good infrared confinement [9][10]. Recent research discussed the theoretical possibility to use negative index materials helps confine the plasmons in graphene [11]. The materials with the negative index properties could provide very small light confinement due to the superlens effect [12].…”