Control the Raman response of individual carbon nanotubes by orbital angular momentum of light

We propose and demonstrate an approach for tailoring the Raman response of an individual single-walled carbon nanotube (SWNT) by employing the optical vortex as the excitation. Specifically, we observe the blueshifts of radial breathing mode and G mode when the topological charge of the vortex beam is increased from 0 to 5. Further theoretical analysis yields that the optical absorption and the corresponding laser heating effect of SWNT are inversely proportional to the topological charge of the optical vortex. Such a decrease in the laser heating effect weakens the softening of C-C bonds, leading to the blueshifts of Raman modes.