Single-walled carbon nanotubes as excitonic optical wires
Although metallic nanostructures are useful for nanoscale optics, all of their key optical properties are determined by their geometry. This makes it difficult to adjust these properties independently, and can restrict applications. Here we use the absolute intensity of Rayleigh scattering to show that single-walled carbon nanotubes can form ideal optical wires. The spatial distribution of the radiation scattered by the nanotubes is determined by their shape, but the intensity and spectrum of the scattered radiation are determined by exciton dynamics, quantum-dot-like optical resonances and other intrinsic properties. Moreover, the nanotubes display a uniform peak optical conductivity of ~8 e^2/h, which we derive using an exciton model, suggesting universal behaviour similar to that observed in nanotube conductance. We further demonstrate a radiative coupling between two distant nanotubes, with potential applications in metamaterials and optical antennas.
© 2011 Macmillan Publishers Limited. Received 25 October 2010; accepted 12 November 2010; published online 19 December 2010 Acknowledgements The authors thank P.L. McEuen for useful discussions, and Y.J. Kim and R. Havener for assistance with sample fabrication and numerical modelling. This work was supported by the National Science Foundation (NSF) through the Center for Nanoscale Systems, Cornell Center for Materials Research, Center for Chemical Innovation and an NSF CAREER grant. Additional funding was received from the David and Lucile Packard Foundation, Alfred P. Sloan Foundation, Camille and Henry Dreyfus Foundation, and the US Department of Defense through the Air Force Office of Scientific Research. Sample fabrication was performed at the Cornell Nanoscale Science and Technology Facility, a National Nanotechnology Infrastructure Network node. Author contributions D.J. and L.H. performed optical measurements and analysed the data. J.K. carried out theoretical calculations. S.-Y.J. and J.J. performed Raman spectroscopy measurements. M.S. carried out nanotube synthesis. G.C. and J.P. supervised the project. Additional information The authors declare no competing financial interests. Supplementary information accompanies this paper at www.nature.com/naturenanotechnology. Reprints and permission information is available online at http://npg.nature.com/reprintsandpermissions/. Correspondence and requests for materials should be addressed to J.P.
Supplemental Material - nnano.2010.248-s1.pdf