Liquid-Crystal Terahertz Quarter-Wave Plate Using Chemical-Vapor-Deposited Graphene Electrodes

Chan Shan Yang, Chun Kuo, Chiu Chun Tang, J. C. Chen, Ru Pin Pan, Ci Ling Pan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Quarter-wave operation or a phase shift of more than π/2, which is approximately ten times greater than that reported in previous works using liquid crystals (LCs) and graphene electrodes, was demonstrated. The device is transparent to the terahertz (THz) wave, and the driving voltage required was as low as approximately 2.2 V (rms), which is also unprecedented. Experimental results supported a theoretical formalism adapted for LC cells with THz wavelength-scale thickness. The scattering rate, DC mobility, and carrier mean free path of bilayer graphene were also determined using THz spectroscopic techniques; the parameters were inferior to those of monolayer graphene. This observation can be attributed to the higher density of charged impurities in the bilayer graphene. The device performances of LC phase shifters using monolayer and bilayer graphene as electrodes were essentially identical.

Original languageEnglish
Article number7347325
JournalIEEE Photonics Journal
Issue number6
Publication statusPublished - 2015 Dec
Externally publishedYes


  • Far infrared or terahertz
  • birefringence
  • liquid crystals
  • liquid-crystal devices
  • nanomaterials
  • phase shift
  • spectroscopy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


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