Room temperature terahertz electro-optic modulation by excitons in carbon nanotubes

We have investigated the electroabsorption of aligned micelle-wrapped single-walled carbon nanotubes induced by intense terahertz (THz) pulses by using THz-pump and optical-probe spectroscopy at room temperature. The electroabsorption signal is enhanced at exciton resonances near the optical communication wavelength. The signal showed a quadratic dependence on the THz electric field and instantaneously followed the THz oscillation (similar to 1 ps). The observed ultrafast electro-optic modulation with a THz bandwidth suggests the potential functionality of carbon nanotubes in high-speed electro-optic devices. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3470105]