Infrared and optical properties of carbon nanotube dipole antennas

The characteristics of armchair carbon nanotube dipole antennas are investigated in the infrared and optical regime. The analysis is based on a classical electromagnetic Hallen's-type integral equation, and an axial quantum mechanical conductance function for the tube. It is found that, within a certain frequency span in the GHz-THz range, finite-length carbon nanotube dipoles resonate at approximately integer multiples of one-half of a plasma wavelength. Outside of this range, current resonances are strongly damped. In the optical regime, antenna properties are strongly modulated by interband transitions. General antenna characteristics of finite-length carbon nanotube dipoles are presented, such as input impedance, current profile, gain, and efficiency, and radiation patterns are discussed.