Abstract-Generation of terahertz radiation by optical excitation of aligned carbon nanotubes

Lyubov Titova , Cary L. Pint , Qi Zhang , Robert H. Hauge , Junichiro Kono , and Frank Hegmann

Nano Lett., Just Accepted Manuscript

DOI: 10.1021/acs.nanolett.5b00494

Publication Date (Web): April 16, 2015

Copyright © 2015 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.5b00494

We have generated coherent pulses of terahertz radiation from macroscopic arrays of aligned single-wall carbon nanotubes (SWCNTs) excited by femtosecond optical pulses without externally applied bias. The generated terahertz radiation is polarized along the SWCNT alignment direction. We propose that top-bottom asymmetry in the SWCNT arrays produces a built-in electric field in semiconducting SWCNTs, which enables generation of polarized terahertz radiation by a transient photocurrent surge directed along the nanotube axis.

Abstract-Carbon Nanotube Terahertz Detector

Xiaowei He , Naoki Fujimura , Jennifer Meagan 

Lloyd , Kristopher Erickson , Qi Zhang , Weilu Gao, Qijia Jiang , Yukio Kawano , Robert H. Hauge ,Francois Leonard , and Junichiro Kono

Nano Lett., Just Accepted Manuscript

DOI: 10.1021/nl5012678

Publication Date (Web): May 29, 2014

Copyright © 2014 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/nl5012678?journalCode=nalefd

Terahertz (THz) technologies are promising for diverse areas such as medicine, bioengineering, astronomy, environmental monitoring, and communications. However, despite decades of world-wide efforts, the THz region of the electromagnetic spectrum still continues to be elusive for solid state technology. Here, we report on the development of a powerless, compact, broadband, flexible, large-area, and polarization-sensitive CNT THz detector that works at room temperature. The detector is sensitive throughout the entire range of the THz technology gap, with responsivities as high as 2.5 V/W and polarization ratios as high as 5:1. Complete thermoelectric and opto-thermal characterization together unambiguously reveal the photothermoelectric origin of the THz photosignal, triggered by plasmonic absorption and collective antenna effects, and suggest that judicious design of thermal management and quantum engineering of Seebeck coefficients will lead to further enhancement of device performance.