Excitonic Resonances in Coherent Anti-Stokes Raman Scattering from Single-Walled Carbon Nanotubes

In this work, we investigate the role of exciton resonances in coherent anti-Stokes Raman scattering (er-CARS) in single-walled carbon nanotubes (SWCNTs). We drive the nanotube system in simultaneous phonon and excitonic resonances, and we observe a superior enhancement by orders of magnitude exceeding nonresonant cases. We investigated the resonant effects in several (n, m) chiralities and found that the er-CARS intensity varies more than 4 orders of magnitude between nanotube species determined by excitonic resonant condition. The experimental finding is compared to a perturbation theory model. Finally, we show that such giant resonant nonlinear signals enable rapid mapping and local heating of individualized CNTs, suggesting easy tracking of CNTs for future nanotoxicology studies and therapeutic applications in biological tissues.