Terahertz Applications of Carbon Nanotube Nanomaterials

Carbon nanotube (CNT) nanomaterials have emerged as a versatile platform for the manipulation, detection and generation of terahertz (THz) radiation, spanning frequencies from roughly 0.1 to 10 THz. Their one-dimensional structure, high carrier mobility and strong light–matter interaction enable a range of functionalities, including ultrafast modulation, tunable polarisation control, enhanced transmission and plasmonic confinement. Both single-walled and multi-walled CNT assemblies can be engineered into films, metamaterials or metasurfaces, offering mechanical flexibility, broadband operation and compatibility with stretchable substrates. Advances in fabrication methods, such as aligned forests, patterned gratings and strain-induced buckling, have realised active THz polarizers, high-depth modulators and dynamic sensors. On the emission side, exciton autoionisation and impact excitation in semiconducting CNTs support efficient THz photogeneration. Quantum plasmonic effects in aligned nanotube arrays further open routes to gate-tunable THz optoelectronics. Together, these developments point towards practical THz devices for imaging, communications, spectroscopy and wearable sensing.

Research from Nature Portfolio

Recent studies have demonstrated quantum plasmon resonances in gated films of aligned single-walled CNTs. By varying carrier density via electrical gating, researchers observed a distinct intersubband plasmon absorption peak in the near-infrared, laying groundwork for CNT-based optoelectronic switches and modulators operating at THz and adjacent bands. This work highlights the interplay between one-dimensional confinement and collective electronic oscillations.

Complementary investigations of super-aligned multi-walled CNT films have elucidated their dielectric and conductive behaviour in the 0.1–2.5 THz range. Measurements reveal strong anisotropy in permittivity and conductivity, which, when combined with subwavelength aperture patterning, yield extraordinarily enhanced THz transmission through the CNT substrate. Surface plasmon polaritons at the nanotube–air interface underpin this effect, offering design principles for compact THz filters and sensors.

Terahertz Applications of Carbon Nanotube Nanomaterials publication trend

The graph below shows the total number of articles in terahertz applications of carbon nanotube nanomaterials across all publications each year (not limited to Nature Index journals).

Technical terms

Terahertz radiation: Electromagnetic waves in the 0.1–10 THz frequency range, situated between microwaves and infrared light.

Carbon nanotube: Cylindrical nanostructure formed by rolling graphene sheets, noted for exceptional electrical and mechanical properties.

Surface plasmon polariton: Hybrid excitation of electrons and electromagnetic fields confined to a material interface, enabling subwavelength guiding.

Exciton: Bound pair of an electron and a hole in a semiconductor, fundamental to light-matter interactions and emission processes.

Metasurface: Two-dimensional arrangement of subwavelength elements designed to tailor the phase, amplitude or polarisation of incident waves.

References

1. Ultrafast Optomechanical Terahertz Modulators Based on Stretchable Carbon Nanotube Thin Films. Ultrafast Science (2023).
2. Intersubband plasmons in the quantum limit in gated and aligned carbon nanotubes. Nature Communications (2018).
3. Terahertz Dispersion Characteristics of Super-aligned Multi-walled Carbon Nanotubes and Enhanced Transmission through Subwavelength Apertures. Scientific Reports (2018).
4. Tailoring terahertz surface plasmon wave through free-standing multi-walled carbon nanotubes metasurface.. Optics Express (2018).
5. Terahertz Excitonics in Carbon Nanotubes: Exciton Autoionization and Multiplication. Nano Letters (2020).