Nonlinear optical responses induced by Auger ionization in single-walled carbon nanotubes

Abstract

We theoretically study the optical response of single-walled carbon nanotubes (SWNTs) under high-intensity laser irradiation. Due to the quasi-onedimensional structure of SWNTs, the Coulomb interaction between excitons is enhanced relative to the bulk. As a result, excitons can be ionized to electrons and holes by the Auger ionization process under high-intensity laser irradiation. Taking into account the effect of Auger-ionized carriers, we calculate absorption spectra by solving the Bethe-Salpeter equation in the tightbinding approximation. We found that Auger-ionized carriers induce a bandgap renormalization and a bleaching of excitons, leading to a nonlinear optical response. Our calculation reveals the strong influence of Auger-ionized carriers on excitons under high-intensity laser irradiation, which may unravel the recently observed nonlinear behavior of photoluminescence emission spectra. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.