  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, where we observe a superior enhancement by orders of magnitude
exceeding non-resonant cases. We investigated the resonant effects in five
$(n,m)$ chiralities and find that the er-CARS intensity varies drastically
between different nanotube species. The experimental results are compared with
a perturbation theory model. Finally, we show that such giant resonant
non-linear signals enable rapid mapping and local heating of individualized
CNTs, suggesting easy tracking of CNTs for future nanotoxology studies and
therapeutic application in biological tissues.
