Generation of Terahertz Radiation by Wave Mixing in Zigzag Carbon Nanotubes

TL;DR

This paper demonstrates that wave mixing in zigzag carbon nanotubes can generate terahertz radiation by exploiting their nonparabolic electron energy bands, with potential applications in terahertz source development and electron relaxation time measurement.

Contribution

It introduces a semiclassical model for terahertz generation in zigzag carbon nanotubes via wave mixing, highlighting the role of band nonparabolicity and phase shift effects.

Findings

Negative current observed in wave mixing

Current inversion depending on phase shift

Negative differential conductivity in nanotubes

Abstract

With the use of the semiclassical Boltzmann equation we have calculated a direct current (d.c) in undoped zigzag carbon nanotube (CN) by mixing two coherent electromagnetic waves with commensurate frequencies i.e and . This effect is attributed to the nonparabolicity of the electron energy band which is very strong in carbon nanotubes. We observed that the current is negative similar to that observed in superlattice. However if the phase shift lies between and there is an inversion and the current becomes positive. It is interesting to note that exhibit negative differential conductivity as expected for d.c through carbon nanotubes. This method can be used to generate terahertz radiation in carbon nanotubes. It can also be used in determining the relaxation time of electrons in carbon nanotubes