P T Symmetry and Singularity-Enhanced Sensing Based on Photoexcited Graphene Metasurfaces

Pai Yen Chen, Jeil Jung

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116 Scopus citations


We introduce here a parity-time-(PT) symmetric system using an optically pumped, active graphene metasurface paired with a resistive metallic filament, realizing a unidirectional reflectionless propagation of terahertz (THz) waves. The amplified THz stimulated emission and tailored plasmon resonances in the graphene metasurface may achieve an equivalent negative-resistance converter at THz frequencies. We theoretically demonstrate that the combination of the spectral singularity in a PT-symmetric system and the chemical sensitivity of graphene may give rise to exotic scattering responses, strongly influenced by the presence of charged impurities in graphene at the spontaneous PT-symmetry-breaking point. This graphene-based PT-symmetric device may have broad relevance beyond the extraordinary manipulation of THz waves, as it may also open exciting prospects for detecting gas, chemical, and biological agents with high sensitivities.

Original languageEnglish
Article number064018
JournalPhysical Review Applied
Issue number6
StatePublished - 29 Jun 2016


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