Towards loss compensated and lasing terahertz metamaterials based on optically pumped graphene

Abstract

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 and the proper conditions for terahertz amplification in single layer graphene are determined. It is shown that amplification in graphene occurs for temperatures up to room temperature and for moderate pump intensities when pumped at a telecommunication wavelength $\lambda =1.5\mu \mathrm{m}$. Furthermore, the amplification properties of graphene are evaluated and discussed at a temperature as low as $T=77\mathrm{K}$ and a pump intensity $I=300mW/m{\mathrm{m}}^2$ to investigate the coupling between graphene and a plasmonic split ring resonator (SRR) metamaterial. The contributions of ohmic and dielectric loss mechanisms are studied by full wave simulations. As a result, it is found that the loss of a split-ring resonator metamaterial can be compensated by optically stimulated amplification in graphene. Moreover, it is shown that a hybrid material consisting of asymmetric split-ring resonators and optically pumped graphene can exceed the laser threshold condition and can emit coherent THz radiation at minimum output power levels of $60nW/m{\mathrm{m}}^2$. The use of optically pumped graphene is well suited for loss compensation in THz metamaterials and paves the way to new kinds of coherent THz sources.

12 pages, 7 figures

References in corpus (4)

• The optical conductivity of graphene in the visible region of the spectrum
• Space-time dispersion of graphene conductivity
• A comparison of graphene, superconductors and metals as conductors for metamaterials and plasmonics
• Metamaterial near-field sensor for deep-subwavelength thickness measurements and sensitive refractometry in the terahertz frequency range

Cited by in corpus (5)

• Tunable Terahertz Amplification Based on Photoexcited Active Graphene Hyperbolic Metamaterials
• Carrier-carrier scattering and negative dynamic conductivity in pumped graphene
• Recent advances in terahertz photonic technologies based on graphene and their applications
• Terahertz topological plasmon polaritons for robust temperature sensing
• Ultra-compact injection terahertz laser using the resonant inter-layer radiative transitions in multi-graphene-layer structure