Abstract-Anisotropic high-field terahertz response of free-standing carbon nanotubes

Byounghwak Lee1, Ali Mousavian1, Michael J. Paul1, Zachary J. Thompson1, Andrew D. Stickel1, Dalton R. McCuen1, Eui Yun Jang2, Yong Hyup Kim2, Jisoo Kyoung3, Dai-Sik Kim3 and Yun-Shik Lee1,a)

1 Department of Physics, Oregon State University, Corvallis, Oregon 97331-6507, USA

2 School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744, South Korea

3 Department of Physics and Astronomy, Seoul National University, Seoul 151-747, South Korea

a) Electronic mail: leeys@physics.oregonstate.edu

Appl. Phys. Lett. 108, 241111 (2016); http://dx.doi.org/10.1063/1.4954222
http://scitation.aip.org/content/aip/journal/apl/108/24/10.1063/1.4954222

We demonstrate that unidirectionally aligned, free-standing multi-walled carbon nanotubes (CNTs) exhibit highly anisotropic linear and nonlinear terahertz (THz) responses. For the polarization parallel to the CNTaxis, strong THz pulses induce nonlinear absorption in the quasi-one-dimensional conducting media, while no nonlinear effect is observed in the perpendicular polarization configuration. Time-resolved measurements of transmitted THz pulses and a theoretical analysis of the data reveal that intense THz fields enhance permittivity in carbon nanotubes by generating charge carriers.