Plasmonic Enhancement of Terahertz Devices Efficiency

First, a short introduction into different carbon allotropies (diamond, graphite, fullerene, carbon nanotubes and grapheme) will be given. Graphene and more complex graphene-based structures attracted a considerable attention recently. The gapless energy spectrum of graphene implies that graphene can absorb and emit photons with rather low energies corresponding to terahertz (THz) and infrared (IR) frequencies. Then plasmonic effect will be introduced for bulk materials and for 2-D structures.

The main part of the presentation reviews plasmonic enhancement of graphene THz photodetectors (PD) and light emitters (LE). It is demonstrated that devices based on double graphene-layer (DGL) or multiple graphene layer structures with the graphene layers separated by thin tunnel barrier layers have advantages over the single graphene-layer (SGL) devices. In DGLs, this advantage is due to the photon-assisted resonant tunneling when the band offset of the graphene layers is aligned to the THz photon energy. The resonant emission or absorption of the THz radiation is enhanced by the cooperative resonant excitation of the graphene plasmons leading to an extremely high gain and/or responsivity in the graphene THz device structures. All major principals of discussed THz devices were confirmed experimentally at RIEC of Tohoku University and especially: world-first single-mode THz lasing has been demonstrated in a Distributed Feedback Dual Gate Graphene Field Effect Transistor.

All Faculty, staff and students are invited
Coffee will be served in the Department of Physics
SP-367-11 at 2:30  PM
Information: 514 848-2424 ext. 3270