Anisotropic Properties of Ultra-Thin Freestanding Multi-Walled Carbon Nanotubes Film for Terahertz Polarizer Application

• Published in: IEEE transactions on terahertz science and technology Vol. 6; no. 2; pp. 278 - 283
• Main Authors: Wang, Yue, Yin, Jing-hua, Wu, Qun, Tong, Yijing
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.03.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Absorption; Anisotropy; Carbon; Carbon nanotubes; Degree of polarization; Dopants; Erbium; Extinction ratio; Frequency modulation; Multi wall carbon nanotubes; multi-walled carbon nanotubes (MWCNTs); Nanotubes; Optoelectronic devices; Polarization; Polarizers; Polytetrafluoroethylenes; terahertz (THz); Time-domain analysis
• ISSN: 2156-342X; 2156-3446
• DOI: 10.1109/TTHZ.2016.2525776

Anisotropic transmission of ultrathin freestanding multi-walled carbon nanotubes (MWCNTs) film has been investigated using terahertz (THz) time-domain spectroscopy. The super-aligned MWCNTs films were fabricated by a novel method-drawing and winding carbon nanotubes on square-shaped polytetrafluoroethylene (PTFE) frame. The MWCNTs film exhibited anisotropic transmittance of THz wave depending on the alignment direction of carbon nanotubes relative to the THz wave polarization orientation, which proved that such MWCNTs film acts as an ideal polarizer in the THz regime. The degree of polarization (DOP) of 99.4% and the extinction ratio (ER) of 25.3 dB (average value) has been demonstrated for a MWCNTs film of 9- μm thickness in a wide frequency range from 0.1 to 2.5 THz. Furthermore, the value of DOP and ER can be engineered expediently by controlling the film thickness. Our approach opens the possibility of MWCNTs film in application of THz optoelectronic devices.