Plasmons In Two-dimensional Electron Gas Research Articles

二维电子气等离激元太赫兹波器件

二维电子气等离激元太赫兹波器件

Deep Sub-Wavelength Multimode Tunable In-Plane Plasmonic Lenses Operating at Terahertz Frequencies

We report on focusing of terahertz (THz) plasmons in two-dimensional electron gas (2DEG) at III-N heterostructures and in graphene by using planar circular grating lenses. Propagation of a broadband pulse of EM waves in 0.5-10 THz is studied by using finite difference time-domain (FDTD) approach. The results show that plasmonic modes excited by incident THz radiation are concentrated into λ/180 area localized under the central disc. Electric field intensity under the central point is found to be orders of magnitude larger than the outer grating area. Optimal geometries for enhanced radiation coupling and plasmon focusing are investigated. Plasmonic lens modes supported by system has the advantage of tunability by an applied voltage to gratings. The large field enhancement by plasmonic confinement presents the potential for sub-wavelength imaging.

The evolution of sheet-plasmon behavior in silver monolayers on Si(1 1 1)-( [formula omitted])-Ag surface

The dispersion of sheet plasmons in two-dimensional electron gas (2DEG) systems prepared on Si(1 1 1)-( 3 × 3 )-Ag surface was investigated by angle-resolved high-resolution electron-energy-loss spectroscopy (HREELS) in an in-situ ultrahigh vacuum environment. The evolution of dispersion at the low coverage of additional silver adatoms shows a behavior associating with two-dimensional adatom gas phase and the critical coverage to sustain this phase is also determined. Dispersion at higher coverage of additional silver adatoms features a gap opening in the long wavelength limit (momentum q → 0 ), suggesting a new mode of plasmon. A calculation based on the theory of surface plasmons implies this plasmon is 3D-type surface plasmon and reveals a smooth transition from a 2D sheet plasmon to a 3D surface plasmon.

Interaction of charged particle flows with plasmons in two-dimensional electron gas

The theory of interaction of charged particle beams with 2D electron gas, located in the field of the delta-like potential wallU(y) =Uoδ(y) has been developed. The kinetic equation for plasmons in 2D electron gas was obtained; the conditions of arising of their instability are given and the corresponding expressions for the increment of plasmons are found.

Plasmon excitations in Josephson arrays and thin superconducting layers.

Long-wave excitations in Josephson arrays are investigated. The existence of excitations with square root or acoustic dispersion law, like plasmons in two-dimensional electron gas, is predicted. Observation of such excitations with frequency much lower than the frequency of the superconducting gap \ensuremath{\Delta}/\ensuremath{\Elzxh} is possible by use of a grating and the same far infrared or microwave techniques used for detection of the plasmons in semiconductor microstructures.