Abstract-Graphene-based tunable metamaterial terahertz filters

Kai Yang¹, Shuchang Liu¹, Sara Arezoomandan¹, Ajay Nahata¹ and Berardi Sensale-Rodriguez^1,a)
http://scitation.aip.org/content/aip/journal/apl/105/9/10.1063/1.4894807
1 Department of Electrical and Computer Engineering, The University of Utah, 50 S. Central Campus Dr., Salt Lake City, Utah 84112, USA
a) Electronic mail: berardi.sensale@utah.edu
Appl. Phys. Lett. 105, 093105 (2014); http://dx.doi.org/10.1063/1.4894807

We propose and describe a micro-machined tunable metamaterial terahertz filter based ongraphene. The device structure consists of periodic metallic rings with several gaps where tunablegraphene stripes are located. We demonstrate that the filter resonance frequency can be adjusted easily by varying the conductivity of graphene and implement this by changing the number of stacked graphene layers. Moreover, the proposed design is scalable, in the sense that the resonance frequency tuning can be controlled by scaling the inner and outer radius of the metal rings. Using numerical simulations and terahertz time-domain spectroscopy measurements of the fabricated samples, we show that the resonance frequency of the structure can be altered by 40% (i.e., from ∼0.2 THz to ∼0.12 THz) by simply tuning the conductivity of graphene. Importantly, the active area of the device is ≪0.1% of the total unit cell area, which can boost the device speed upon electrostatic actuation.

Abstract-Graphene-based electrically reconfigurable deep-subwavelength metamaterials for active control of THz light propagation

• Sara Arezoomandan, 
• Kai Yang, 
• Berardi Sensale-Rodriguez

http://link.springer.com/article/10.1007%2Fs00339-014-8693-8

This work studies the terahertz light propagation through

graphene-based reconfigurable metasurfaces where the unit cell dimensions are much smaller than the terahertz wavelength. The proposed devices, which poses deep-subwavelength unit cell and active region dimensions can operate as amplitude and/or phase modulators in certain specific frequency bands determined by the device geometry. Reconfigurability is attained via electrostatically tuning the optical conductivity of patterned graphene layers, which are strategically located in each unit cell. The ultra-small unit cell dimensions can be advantageous for beam shaping applications.