Consistent analysis and rigorous characterization of infinite graphene layers via a subcell frequency-dependent FDTD technique

Abstract

An efficient finite-difference time-domain methodology combined with a robust subcell formulation for the precise analysis of infinite graphene sheets is introduced in this paper. The graphene surface conductivity is modeled through a volume conductivity profile, with the pertinent periodic boundary conditions applied to the unit cell's lateral surfaces. Moreover, a set of linearly-polarized normally-incident wideband pulses excites the computational domain, while the graphene's dispersive nature is described by an auxiliary differential equation concept. The novel algorithm is validated via several configurations and a demanding optical visibility problem, whose numerical results, compared to those of closed-form expressions, are proven very satisfactory.

A Perfectly Matched Layer for Subcell FDTD and Applications to the Modeling of Graphene Structures

“…The functionality and accuracy of the subcell PML scheme for a dispersive sublayer can be tested by simulating a graphene slab structure [9]. The geometry of the test structure is shown in Fig.…”

A terahertz photomixer based on plasmonic nanoantennas coupled to a graphene emitter

“…of the fact that graphene can provide a flat ultrathin substrate to tailor strong light-matter interactions in the terahertz (THz) and infrared range [12][13][14][15][16]. In addition to its extreme thinness, graphene is appealing for its gate-tunable plasmon resonance of massless Dirac fermions, enabling wideband tunability in photonic and optoelectronic nanodevices, such as plasmonic oscillators [17], flatland transformation optics and tunable metamaterials [18,19], cloaking devices [20], terahertz wave switches [21], modulators [22] and phase shifters [23].…”

“…where ε ox = 3.9 is the relative permittivity of silicon dioxide (SiO 2 ) filling the waveguide, ε 0 and µ 0 are respectively the vacuum permittivity and permeability, σ s is the complex surface conductivity derived from the Kubo formula [14]; see appendix for details. The first term in C es represents the parallel-plate capacitance between the two graphene sheets and the second term is the fringing capacitance [52], negligible when w d. In the THz range, σ s follows a Drude-type dispersion σ s = −j(q 2 E F /π h2 )/(ω − j ), where is the carrier intraband scattering rate ( = 0.065 meV for high-quality graphene [13]) and the plasmon spectrum is tunable by Fermi energy E F . From the transmission-line theory, the propagation constant and characteristic impedance may then be calculated using…”

Προηγμένες Τεχνικές Μοντελοποίησης Γραφενίου Με Εφαρμογές Στην Ηλεκτρομαγνητική Συμβατότητα

“…Η δημοφιλη ς με θοδος των Πεπερασμε νων Διαφορω ν στο Πεδι ο του Χρο νου (Finite-Difference Time-Domain, FDTD) [163] ει ναι μι α απο αυτε ς και ξεχωρι ζει για την απλο τητα της και την ευρυζωνικη ανα λυση, με αποτε λεσμα να αναπτυχθου ν ταχυ τατα τροποποιη σεις της για τη μοντελοποι ηση του γραφενι ου. Συγκεκριμε να, σε μι α απο τις πρω τες προσπα θειες, η αναπαρα σταση του γραφενι ου γινο ταν ως μια χωρικη κατανομη ρευ ματος, που καταλα μβανε ε να τμη μα απο το στοιχειω δες κελι της μεθο δου [164,165], ενω επεκτα θηκαν οι συμβατικε ς απορροφητικε ς συνθη κες για να λαμβα νουν υπο ψη και το γραφε νιο [166]. Ωστο σο, συ ντομα αυτη τεχνικη εγκαταλει πεται, καθω ς ει ναι ορθο τερη η μοντελοποι ηση του διδια στατου υλικου , με σω της επιφανειακη ς του αγωγιμο τητας, κι ε τσι προτει νεται η εισαγωγη του ως επιφανειακο ρευ μα [167].…”