Tuesday, August 4, 2015

Abstract-Tunable surface plasmon instability leading to emission of radiation

We propose a new approach for energy conversion from a dc electric field to tunable terahertz emission based on hybrid semiconductors by combining two-dimensional (2D) crystalline layers and a thick conducting material with possible applications for chemical analysis, security scanning, medical (single-molecule) imaging, and telecommunications. The hybrid nano-structure may consist of a single or pair of sheets of graphene, silicene, or a 2D electron gas.When an electric current is passed through a 2D layer, we discover that two low-energy plasmon branches exhibit a characteristic loop in their dispersion before they merge into an unstable region beyond a critical wave vector . This finite gives rise to a wavenumber cutoff in the emission dispersion of the surface plasmon induced instability and emission of radiation(spiler). However, there is no instability for a single driven layer far from the conductor, and theinstability of an isolated pair of 2D layers occurs without a wavenumber cutoff. The wavenumber cutoff is found to depend on the conductor electron density, layer separation, distances of layers from the conductor surface, and the driving-current strength.

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