Related papers: Nonlinear THz Conductivity Dynamics in CVD-Grown G…
It is evidenced by numerical calculations that optically pumped graphene is suitable for compensating inherent loss in terahertz (THz) metamaterials. In a first step, the complex conductivity of graphene under optical pumping is calculated…
We report a terahertz optical modulator consisting of randomly stacked trilayer graphene (TLG) deposited on an oxidized silicon substrate by means of THz- Time Domain Spectroscopy (THz-TDS). Here, the gate tuning of the Fermi level of the…
Monolayer graphene absorbs 2.3 percent of the incident visible light. This 'small' absorption has been used to emphasize the visual transparency of graphene, but it in fact means that multilayer graphene absorbs a sizable fraction of…
Graphene has been one of the most investigated materials in the last decade. Its unique optoelectronic properties have indeed raised it to an ideal and revolutionary candidate for the development of entirely novel technologies across the…
We calculate the finite-frequency conductivity of bilayer graphene with a relative twist between the layers. The low frequency response at zero doping shows a flat conductivity with value twice that of the monolayer case and at higher…
We investigate the contribution of charge puddles to the non-vanishing conductivity minimum in disordered graphene flakes at the charge neutrality point. For that purpose, we study systems with a geometry that suppresses the transmission…
Momentum and energy balance equations are developed for steady-state electron transport and optical absorption under the influence of a dc electric field, an intense ac electric field of terahertz (THz) frequency in a two-dimensional (2D)…
Transfer of graphene, grown by Chemical Vapor Deposition (CVD), to a substrate of choice, typically involves deposition of a polymeric layer (typically, poly(methyl methacrylate, PMMA or polydimethylsiloxane, PDMS). These polymers are quite…
We present magnetoresistance measurements on large scale monolayer graphene grown by chemical vapor deposition (CVD) on copper. The graphene layer was transferred onto SiO2/Si via PMMA and thermal release tape for transport measurements.…
We measured Drude absorption of gated CVD graphene using far-infrared transmission spectroscopy, and determined carrier scattering rate (g) as function of the varied carrier density (n). The n-dependent g(n) was obtained for a series of…
Carrier dynamics in single-layer graphene grown by chemical vapor deposition (CVD) is studied using spatially and temporally resolved pump-probe spectroscopy by measuring both differential transmission and differential reflection. By…
We present a comparative study of high carrier density transport in mono-, bi-, and trilayer graphene using electric-double-layer transistors to continuously tune the carrier density up to values exceeding 10^{14} cm^{-2}. Whereas in…
Nonlinear-optical refraction is typically described by means of perturbation theory near the material's equilibrium state. Graphene, however, can easily move far away from its equilibrium state upon optical pumping, yielding strong…
Optical reflectivity and transmission measurements over photon energies between 0.2 and 1.2 eV were performed on single-crystal graphene samples on a transparent SiO2 substrate. For photon energies above 0.5 eV, graphene yielded a…
We investigate the absorption properties of graphene-based anisotropic metamaterial structures where the metamaterial layer possesses an electromagnetic response corresponding to a near-zero permittivity. We find that through analytical and…
We obtain the output characteristics of graphene field-effect transistors by using the charge-control model for the current, based on the solution of the Boltzmann equation in the field-dependent relaxation time approximation. Closed…
We present results for time-dependent electron transport in a ballistic graphene field-effect transistor with an ac-driven gate. Nonlinear response to the ac drive is derived utilizing Floquet theory for scattering states in combination…
Graphene has exceptional optical, mechanical and electrical properties, making it an emerging material for novel optoelectronics, photonics and for flexible transparent electrode applications. However, the relatively high sheet resistance…
Graphene devices are known to have the potential to operate THz signals. In particular, graphene field-effect transistors have been proposed as devices to host plasmonic instabilities in the THz realm; for instance, Dyakonov-Shur…
Graphene exhibits extremely strong optical nonlinearity when a strong perpendicular magnetic field is applied, the response current shows strong field dependence even for moderate light intensity, and the perturbation theory fails. We…