Abstract-Harvesting Plasmonic Excitations in Graphene for Tunable Terahertz/Infrared Metamaterials

Yuancheng Fan^1∗, Fuli Zhang¹, Quanhong Fu¹ and Hongqiang Li<sup>2

http://www.intechopen.com/books/recent-advances-in-graphene-research/harvesting-plasmonic-excitations-in-graphene-for-tunable-terahertz-infrared-metamaterials</sup>
(W)e focus on the development on tunable terahertz/infrared metamaterials enabled with plasmonic excitations in graphene micro-/nanostructures. We aimed the issue (sic), that high loss in the plasmonic excitations of graphene limits the performance of graphene’s ability in manipulating light. We show the enhancement of light-graphene interactions by employing plasmonic metamaterial design for proper plasmonic excitations, and coherent modulation on optical fields to further increase the bonding of light field for boosted plasmonic excitations. The enhanced plasmonic excitations in graphene provide the possibility of practical applications for terahertz and infrared band graphene photonics and optoelectronics.

Abstract-Electrically Tunable Goos–Hänchen Effect with Graphene in the Terahertz Regime

1. Yuancheng Fan^1,*, 
2. Nian-Hai Shen², 
3. Fuli Zhang¹, 
4. Zeyong Wei³, 
5. Hongqiang Li³,
6. Qian Zhao⁴, 
7. Quanhong Fu¹, 
8. Peng Zhang²,
9. Thomas Koschny² and
10. Costas M. Soukoulis^2,5

Version of Record online: 14 JUL 2016

DOI: 10.1002/adom.201600303

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

http://onlinelibrary.wiley.com/doi/10.1002/adom.201600303/abstract

Goos–Hänchen (G–H) effect is of great interest in the manipulation of optical beams. However, it is still fairly challenging to attain efficient controls of the G–H shift for diverse applications. Here, a mechanism to realize tunable G–H shift in the terahertz regime with electrically controllable graphene is proposed. Taking monolayer graphene covered epsilon-near-zero metamaterial as a planar model system, it is found that the G–H shifts for the orthogonal s-polarized and p-polarized terahertz beams at oblique incidence are positive and negative, respectively. The G–H shift can be modified substantially by electrically controlling the Fermi energy of the monolayer graphene. Reversely, the Fermi energy dependent G–H effect can also be used as a strategy for measuring the doping level of graphene. In addition, the G–H shifts of the system are of strong frequency-dependence at oblique angles of incidence, therefore the proposed graphene hybrid system can potentially be used for the generation of terahertz “rainbow,” a flat analog of the dispersive prism in optics. The proposed scheme of hybrid system involving graphene for dynamic control of G–H shift will have potential applications in the manipulation of terahertz waves.

Abstract-Tunable terahertz coherent perfect absorption in a monolayer graphene

Yuancheng Fan, Fuli Zhang, Qian Zhao, Zeyong Wei, and Hongqiang Li  »View Author Affiliations

Optics Letters, Vol. 39, Issue 21, pp. 6269-6272 (2014)

http://dx.doi.org/10.1364/OL.39.006269

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-21-6269

Coherent perfect absorber (CPA) was proposed as the time-reversed counterpart to laser: a resonator containing lossy medium instead of gain medium can absorb the coherent optical fields completely. Here, we exploit a monolayer graphene to realize the CPA in a nonresonant manner. It is found that quasi-CPA point exists in the terahertz regime for suspending monolayer graphene, and the CPA can be implemented with the assistance of proper phase modulation among two incident beams at the quasi-CPA frequencies. The graphene-based CPA is found of broadband angular selectivity: CPA point splits into two frequency bands for the orthogonal s and p polarizations at oblique incidence, and the two bands cover a wide frequency range starting from zero frequency. Furthermore, the coherent absorption can be tuned substantially by varying the gate-controlled Fermi energy. The findings of CPA with nonresonant graphene sheet can be generalized for potential applications in terahertz/infrared detections and signal processing with two-dimensional optoelectronic materials.

© 2014 Optical Society of America