Transmission, reflection, and absorption spectroscopy of graphene microribbons in the terahertz region

Abstract

Both transmission and reflection spectra were obtained from graphene microribbons on a SiC substrate, which resonantly coupled with terahertz light through plasmon excitation. An absorption spectrum was also derived from the transmission and reflection spectra. Absorption by the confined intraband plasmons reached 5–10%/layer, which is considerably larger than the wavelength-independent interband absorption of 2.3%/layer. The absorption was found to be larger when the microribbons/substrate sample was illuminated from the back surface than from the ribbon surface because of an interference effect at the surface.

Narrow plasmon resonances enabled by quasi-freestanding bilayer epitaxial graphene

“…The consistency between Drude and Hall mobility is further confirmation of the uniformity of electrical properties since the transmission measurement uses a spot size of ~1 mm 2 . The absorption of QFS BLG, proportional to the real part of the optical conductivity, is about 8-fold higher than that of EG, and a factor of two higher than prior reports for bilayer graphene [41]. This can be understood by considering equation (1); the bilayer composition results in a factor of 2 increase in absorption and since γ is inversely proportional to µ, the optical conductivity for bilayer graphene is further increased about 4-fold.…”

Orbital-hybridization-created optical excitations in Li2GeO3

“…However, STS might be suitable only under a thin-film sample because of very weak quantum currents. Very interestingly, the optical spectroscopy methods of reflectance 30 , absorption 31 and transmission 32 are reliable in verifying the frequency-dependent optical properties. They can provide significant information about the initial excitonic peaks, the greatly reduced threshold excitation frequency, many prominent absorption structures, and the strongest plasmon mode at = 6.0 eV.…”

Plasmon Control Driven by Spatial Carrier Density Modulation in Graphene

“…The substrate was modeled with ε = 4 at = 10.7 μm. Graphene was modeled as a conducting layer with the following surface conductivity − based on the Kubo formula: Here, is the Boltzmann’s constant, T is the temperature, is the reduced Planck’s constant, ω is the frequency of the laser, = is the Fermi energy, with being the Fermi velocity, and τ is the carrier relaxation time in graphene. Here, we only consider the intraband contribution, because the photon energy in this experiment (∼110–120 meV) is smaller than 2 (∼200–800 meV).…”