Fig. 1

Overview of plasmonically coupled carbon nanotube system. a Shematic of an individual single-wall carbon nanotube (SWCNT) suspended across a bowtie antenna. The SWCNT (d < 1 nm) is portrayed with significantly larger scale than actual size for clarity. The SWCNT is separated from the plasmonic gold substrate by a 2 nm atomic layer deposition grown Al₂O₃ spacer layer to prevent optical quenching and short circuit of the nanoplasmonic gap-mode underneath. b Finite-difference time-domain (FDTD) simulation of the corresponding field enhancement distribution profile including finite apex angles with 3 nm radius. Scale bar=100 nm. c Bright-field optical microscope image of the plasmonic array showing four 20 × 100 μm² stripes each containing bowtie antennas with fixed gap size g varying among stripes from 10–20 nm. The larger features are gold markers to enable repositioning to individual SWCNTs. Scale bar=20 μm. d The scanning electron microscope image shows high uniformity and orientation control of the plasmonic system. Scale bar=2 μm. e Zoom into an individual bowtie antenna with 10 nm gap showing sharp and straighth edges. Scale bar=100 nm. f Plasmon resonance spectrum (Q = 6) recorded in dark-field transmision geometry (gray) together with 780 nm pump laser spectrum (red) and exciton emission spectrum of a (5, 4) SWCNT (blue) showing spectral resonance is fullfilled simultaneously for both SWCNT absorption and emission