Abstract-Graphene field effect transistor-based terahertz modulator with small operating voltage and low insertion loss

Graphene field effect transistor-based terahertz modulator with small operating voltage and low insertion loss

Jingbo Liu, Pingjian Li, Yuanfu Chen, Xinbo Song, Fei Qi, Binjie Zheng, Jiarui He, Qiye Wen, and Wanli Zhang

In this work, we report a broadband terahertz wave modulator based on a top-gate graphene field effect transistor with polyimide as the gate dielectric on a PET substrate. The transmission of the terahertz wave is modulated by controlling the Fermi level of graphene via the polyimide as the top-gate dielectric material instead of the traditional dielectric materials. It is found that the terahertz modulator can achieve a modulation depth of ∼20.9% with a small operating gate voltage of 3.5 V and a low insertion loss of 2.1 dB.

© 2016 Chinese Laser Press

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Abstract-Flexible terahertz modulator based on coplanar-gate graphene field-effect transistor structure

Jingbo Liu, Pingjian Li, Yuanfu Chen, Xinbo Song, Qi Mao, Yang Wu, Fei Qi, Binjie Zheng, Jiarui He, Hyunsoo Yang, Qiye Wen, and Wanli Zhang

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-41-4-816

The terahertz (THz) modulators, as an essential component of the THz system, have been developed by many efforts until now. However, the development of flexible THz modulators is hindered due to the lack of flexible THz modulating materials. Herein, for the first time to the best of our knowledge, we demonstrated the feasibility of flexible THz modulators based on the coplanar-gate field-effect transistor (FET) structure of ion-gel/graphene/polyethylene terephthalate. The THz transmittance through this THz graphene modulator can be well controlled with a modulation depth up to 22% by tuning the carrier concentration of graphene via electrical gating. Furthermore, because of the integration of high flexibilities of graphene, ion-gel, and polyethylene terephthalate (PET), the proposed THz graphene modulator shows superior flexible performance, where the modulation properties can be maintained almost unchanged, not only under bending deformations, but also before and after bending 1000 times. In addition, due to the unique structure of ion-gel/graphene/PET, the flexible THz graphene modulator has a low insertion loss (1.2 dB). Therefore, this Letter is expected to be beneficial for the potential applications, ranging from the traditional compact THz system to a new flexible THz technology.

© 2016 Optical Society of America

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