Abstract-Graphene terahertz modulators by ionic liquid gating

Yang Wu, Chan La-o-vorakiat, Xuepeng Qiu, Jingbo Liu, Praveen Deorani, Karan Banerjee, Jaesung Son, Yuanfu Chen, Elbert E. M. Chia, Hyunsoo Yang

http://xxx.tau.ac.il/abs/1506.02363

(Submitted on 8 Jun 2015)

Graphene based THz modulators are promising due to the conical band structure and high carrier mobility of graphene. Here, we tune the Fermi level of graphene via electrical gating with the help of ionic liquid to control the THz transmittance. It is found that, in the THz range, both the absorbance and reflectance of the device increase proportionately to the available density of states due to intraband transitions. Compact, stable, and repeatable THz transmittance modulation up to 93% (or 99%) for a single (or stacked) device has been demonstrated in a broad frequency range from 0.1 to 2.5 THz, with an applied voltage of only 3 V at room temperature.

Abstract-Graphene Terahertz Modulators by Ionic Liquid Gating

1. Yang Wu^1,2, 
2. Chan La-o-vorakiat^3,4,
3. Xuepeng Qiu⁵, 
4. Jingbo Liu⁶, 
5. Praveen Deorani⁵, 
6. Karan Banerjee⁵, 
7. Jaesung Son⁵, 
8. Yuanfu Chen⁶, 
9. Elbert E. M. Chia^4,*and
10. Hyunsoo Yang^1,2,*

Article first published online: 3 FEB 2015

http://onlinelibrary.wiley.com/doi/10.1002/adma.201405251/abstract;jsessionid=4D3B95BDF171BDBF815E1504D6336819.f03t03?deniedAccessCustomisedMessage=&userIsAuthenticated=false

DOI: 10.1002/adma.201405251

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Excellent-performance terahertz (THz) modulators based on graphene/ionic liquid/graphene sandwich structures are demonstrated. The modulation covers a broadband frequency range from 0.1 to 2.5 THz with a modulation depth of up to 99% by applying a small gate voltage of 3 V. The outstanding performance of the proposed devices is due to the conical band structure of the graphene and the powerful gating effect of the ionic liquid in proximity to the graphene.