Abstract-Tunable Graphene Metasurfaces with Gradient Features by Self-Assembly-Based Moiré Nanosphere Lithography

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http://onlinelibrary.wiley.com/doi/10.1002/adom.201600242/full

Patterned arrays of graphene nanostructures, also referred as graphene metasurfaces, have proven to be capable of efficiently coupling with incident light by surface plasmon resonances. In this work, a new type of graphene metasurfaces with moiré patterns using cost-effective and scalable moiré nanosphere lithography (MNSL) is demonstrated. A large gradient in feature size (i.e., from sub-200 nm to 1.1 μm) of the graphene nanostructures exists in single metasurfaces. The in-plane quasi-periodic arrangement of the graphene nanostructures can be easily tuned to form a variety of moiré patterns. The experimental measurement and numerical simulations show that the graphene moiré metasurfaces support tunable and multiband optical responses due the size and shape dependences of surface plasmon resonance modes of graphene nanostructures. It is also demonstrated that the multiband optical responses of graphene moiré metasurfaces can be tuned from mid-infrared (MIR) to terahertz (THz) regimes by choosing polystyrene spheres of different sizes for MNSL. These findings provide a cost-effective and scalable strategy to achieve ultrathin functional devices, including multiband light modulators, broadband biosensors, and multiband photodetectors, which feature tunable and multiband responses in wide range of wavelengths from MIR to THz.

Abstract-Extraordinary Control of Terahertz Beam Reflectance in Graphene Electro-absorption Modulators

 

http://pubs.acs.org/stoken/nanotation/pipe/abs/10.1021/nl3016329

Berardi Sensale-Rodriguez *†, Rusen Yan †‡, Subrina Rafique †, Mingda Zhu †, Wei Li ‡§, Xuelei Liang §,David Gundlach ‡, Vladimir Protasenko †, Michelle M. Kelly †, Debdeep Jena †, Lei Liu †, and Huili Grace Xing *†

^† Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States

^‡ Semiconductor and Dimensional Metrology Division,National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States

^§ Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing, 100871, China

Nano Lett., Article ASAP

DOI: 10.1021/nl3016329

Publication Date (Web): August 3, 2012

Copyright © 2012 American Chemical Society

*E-mail address: bsensale@nd.edu; hxing@nd.edu

 

We demonstrate a graphene-based electro-absorption modulator achieving extraordinary control of terahertz reflectance. By concentrating the electric field intensity in an active layer of graphene, an extraordinary modulation depth of 64% is achieved while simultaneously exhibiting low insertion loss (2 dB), which is remarkable since the active region of the device is atomically thin. This modulator performance, among the best reported to date, indicates the enormous potential of graphene for terahertz reconfigurable optoelectronic devices.