Excitonic nonlinearities in single‐wall carbon nanotubes

Abstract

AbstractExcitons are composite bosons that allow a fair description of the optical properties in solid state systems. The quantum confinement in nanostructures enhances the excitonic effects and impacts the exciton–exciton interactions, which tailor the performances of classical and quantum optoelectronic devices, such as lasers or single‐photon emitters. The excitonic nonlinearities exhibit significant differences between organic and inorganic compounds. Tightly bound Frenkel excitons in molecular crystals are for instance affected by an efficient exciton–exciton annihilation (EEA). This Auger process also governs the population relaxation dynamics in carbon nanotubes that share many physical properties with organic materials. Here, we show that this similarity breaks down for the excitonic decoherence in carbon nanotubes. Original nonlinear spectral‐hole burning experiments bring evidence of pure dephasing induced by exciton–exciton scattering (EES) in the k‐space. This mechanism controls the exciton collision‐induced broadening, as for Wannier excitons in inorganic semiconductors. We demonstrate that this singular behavior originates from the intrinsic one‐dimensionality of excitons in carbon nanotubes, which display unique hybrid features of organic and inorganic systems.