Modulation speed limits of a graphene-based modulator

  • Sheng Qu
  • Congcong Ma
  • Shulong Wang
  • Hongxia Liu
  • Lu Dong


Electro-optical modulators, working at near-infrared range are a key device in modern optical system. Modulation speed is an important parameter to evaluate the performance of an electro-optical modulator. However, the modulation speed which is controlled by contact resistance and quantum capacitance of a graphene-based modulator is difficult to calculate in previous numerical simulation. In this paper, we proposed a method based on a simple structure to calculate the modulation speed. The simulation results show that the modulation speed is approximate 1.2 GHz which is consistent with the experimental results. And the dependence of the modulation speed on the effective oxide thickness (EOT) and doping of graphene are investigated in our work. Meanwhile, we optimize the structure parameters of modulator to promote the modulation speed which can be increased to ~3.6 GHz. The proposed method to evaluate and optimize the modulation speed could have many applications potential for various graphene-based devices.


Graphene Contact resistance Quantum capacitance Modulation speed 



This research is supported by the National Natural Science Foundation of China (Grant Nos. 61376099, 61434007 and 61504100).

Author contributions

Hongxia Liu and Shulong Wang developed the concept. Sheng Qu conceived the design. Lu Dong and Congcong Ma performed the numerical simulations. Hongxia Liu, Shulong Wang and Sheng Qu contributed to writing and finalizing the paper.

Compliance with ethical standards

Conflict of interest

The authors declare no conflict of interest.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Sheng Qu
    • 1
  • Congcong Ma
    • 1
  • Shulong Wang
    • 1
  • Hongxia Liu
    • 1
  • Lu Dong
    • 1
  1. 1.Key Laboratory for Wide Band Gap Semiconductor Materials and Devices of Education, School of MicroelectronicsXidian UniversityXi’anChina

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