Ultrafast electrically driven light emitter is a critical component in the development of the high bandwidth free-space and on-chip optical communications. Traditional semiconductor based light sources for integration to photonic platform have therefore been heavily studied over the past decades. However, there are still challenges such as absence of monolithic on-chip light sources with high bandwidth density, large-scale integration, low-cost, small foot print, and complementary metal-oxide-semiconductor (CMOS) technology compatibility. Here, we demonstrate the first electrically driven ultrafast graphene light emitter that operate up to 10 GHz bandwidth and broadband range (400 ~ 1600 nm), which are possible due to the strong coupling of charge carriers in graphene and surface optical phonons in hBN allow the ultrafast energy and heat transfer. In addition, incorporation of atomically thin hexagonal boron nitride (hBN) encapsulation layers enable the stable and practical high performance even under the ambient condition. Therefore, electrically driven ultrafast graphene light emitters paves the way towards the realization of ultrahigh bandwidth density photonic integrated circuits and efficient optical communications networks.
Theoretical consideration of electromagnetic scattering by single-wall carbon nanotubes (SWNTs) and SWNT arrays requires knowledge of the linear surface conductivity of an SWNT. An expression for the surface conductivity of an infinitely long SWNT was derived by Slepyan et al. [Phys. Rev. B 60, 17136-17149 (1999)]10.1103/PhysRevB.60.17136. The twin purposes of this tutorial are to succinctly discuss the derivation using the density matrix formalism and to provide ready-to-use expressions.
KEYWORDS: Single walled carbon nanotubes, Carbon nanotubes, Terahertz radiation, Near field, Near field scanning optical microscopy, Scattering, Electromagnetism, Optical microscopy, Molecules, Near field optics
The use of carbon nanotubes as optical probes for scanning near-field optical microscopy requires an understanding of their near-field response. As a first step in this direction, we investigated the lateral resolution of a carbon nanotube tip with respect to an ideal electric dipole representing an elementary detected object. A Fredholm integral equation of the first kind was formulated for the surface electric current density induced on a single-wall carbon nanotube (SWNT) by the electromagnetic field due to an arbitrarily oriented electric dipole located outside the SWNT. The response of the SWNT to the near field of a source electric dipole can be classified into two types, because surface-wave propagation occurs with (i) low damping at frequencies less than ~ 200-250 THz and (ii) high damping at higher frequencies. The interaction between the source electric dipole and the SWNT depends critically on their relative location and relative orientation, and shows evidence of the geometrical resonances of the SWNT in the low-frequency regime. These resonances disappear when the relaxation time of the SWNT is sufficiently low. The far-field radiation intensity is much higher when the source electric dipole is placed near an edge of SWNT than at the centroid of the SWNT. The use of an SWNT tip in scattering-type scanning near-field optical microscopy can deliver a resolution less than ~ 20 nm. Moreover, our study shows that the relative orientation and distance between the SWNT and the nanoscale dipole source can be detected.
The thermal radiation from single-wall carbon nanotube has been investigated both in the near- and far-field
zones. The discrete spectrum structure for metallic nanotubes due to the geometrical resonances of surface plasmons is predicted.
The nonlinear optical response of a ingle-wall carbon nanotube (CNT)due to the interaction with femtosecond laser pulses is investigated. The analysis utilizes the quantum kinetic equations for π-electrons with both intra-band and inter-band transitions accounted. In the regime of weak driving fields the kinetic equations have been solved by the perturbation method and the third-order nonlinear usceptibility of different achiral CNTs has been calculated. In the strong driving field regime,a non-perturbative approach using the numerical solution of the quantum kinetic equations in the time domain has been developed and the density of the axial electric
current in CNT has been calculated. The amplitude of this current and the conversion efficiency in dependence on the number of the high-order harmonics, the CNT type, the frequency and the intensity of the driving field have been predicted.