The complex refractive indices of the liquid crystal mixture E7 in the terahertz frequency range

Chan Shan Yang*, Chia Jen Lin, Ru Pin Pan, Christopher T. Que, Kohji Yamamoto, Masahiko Tani, Ci Ling Pan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

102 Citations (Scopus)


We have used terahertz time-domain spectroscopy to investigate the complex optical constants and birefringence of a widely used liquid crystal mixture E7 in both nematic and isotropic phases (26°C-70°C). The extinction coefficient of E7 at room temperature is less than 0.035 and without sharp absorption features in the frequency range of 0.2-2.0 THz. The extraordinary (ne) and ordinary (no) indices of refraction at 26°C are 1.690-1.704 and 1.557-1.581, respectively, giving rise to a birefringence of 0.130-0.148 in this frequency range. The temperature-dependent (26°C-70°C) order parameter extracted from the birefringence data agrees with that in the visible region quite well. Further, the temperature gradients of the terahertz optical constants of E7 are also determined. The optical constants of E7 in the terahertz or sub-millimeter wave range are found to deviate significantly from values predicated by the usual extended Cauchy equations used in the visible and near-infrared.

Original languageEnglish
Pages (from-to)1866-1873
Number of pages8
JournalJournal of the Optical Society of America B: Optical Physics
Issue number9
Publication statusPublished - 2010 Sept 1
Externally publishedYes

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Atomic and Molecular Physics, and Optics


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