Ultrafast Science (Jan 2023)

Ultrafast Optomechanical Terahertz Modulators Based on Stretchable Carbon Nanotube Thin Films

  • Maksim I. Paukov,
  • Vladimir V. Starchenko,
  • Dmitry V. Krasnikov,
  • Gennady A. Komandin,
  • Yuriy G. Gladush,
  • Sergey S. Zhukov,
  • Boris P. Gorshunov,
  • Albert G. Nasibulin,
  • Aleksey V. Arsenin,
  • Valentyn S. Volkov,
  • Maria G. Burdanova

DOI
https://doi.org/10.34133/ultrafastscience.0021
Journal volume & issue
Vol. 3

Abstract

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For terahertz wave applications, tunable and rapid modulation is highly required. When studied by means of optical pump–terahertz probe spectroscopy, single-walled carbon nanotube (SWCNT) thin films demonstrated ultrafast carrier recombination lifetimes with a high relative change in the signal under optical excitation, making them promising candidates for high-speed modulators. Here, combination of SWCNT thin films and stretchable substrates facilitated studies of the SWCNT mechanical properties under strain and enabled the development of a new type of an optomechanical modulator. By applying a certain strain to the SWCNT films, the effective sheet conductance and therefore modulation depth can be fine-tuned to optimize the designed modulator. Modulators exhibited a photoconductivity change of approximately 2 times of magnitude under the strain because of the structural modification in the SWCNT network. Stretching was used to control the terahertz signal with a modulation depth of around 100% without strain and 65% at a high strain operation of 40%. The sensitivity of modulators to beam polarization is also shown, which might also come in handy for the design of a stretchable polarizer. Our results give a fundamental grounding for the design of high-sensitivity stretchable devices based on SWCNT films.