Terahertz graphene optics

• Published in: Nano research Vol. 5; no. 10; pp. 667 - 678
• Main Authors: Rouhi, Nima, Capdevila, Santiago, Jain, Dheeraj, Zand, Katayoun, Wang, Yung Yu, Brown, Elliott, Jofre, Lluis, Burke, Peter
• Format: Journal Article
• Language: English
• Published: Heidelberg Tsinghua Press 01.10.2012; Springer Nature B.V
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Chemical vapor deposition; Chemistry and Materials Science; Condensed Matter Physics; Conductance; Conductivity; Direct current; Electrons; Fourier transforms; Graphene; Materials Science; Measurement techniques; Multilayers; Nanocomposites; Nanomaterials; Nanostructure; Nanotechnology; Optics; Plancks constant; Research Article; United States > US; Single-layer graphene; conductance; terahertz; multilayer graphene; broadband
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-012-0251-0

The magnitude of the optical sheet conductance of single-layer graphene is universal, and equal to e 2 /4 ħ (where 2π ħ = h (the Planck constant)). As the optical frequency decreases, the conductivity decreases. However, at some frequency in the THz range, the conductivity increases again, eventually reaching the DC value, where the magnitude of the DC sheet conductance generally displays a sample- and doping-dependent value between ∼ e 2 / h and 100 e 2 / h . Thus, the THz range is predicted to be a non-trivial region of the spectrum for electron transport in graphene, and may have interesting technological applications. In this paper, we present the first frequency domain measurements of the absolute value of multilayer graphene (MLG) and single-layer graphene (SLG) sheet conductivity and transparency from DC to 1 THz, and establish a firm foundation for future THz applications of graphene.