Wavelength-selective addressing of visible and near-infrared plasmon resonances for SU8 nanolithography

We imprint plasmonic near field enhancements as nanoscale topography
in SU8 photoresist using two-photon absorption from a spectrally filtered broadband supercontinuum light source. Imprinted patterns smaller than 50 nm across are obtained localized at positions of high local field enhancements in gold bow tie antennas, and gold split rings resonant in the
visible and near-infrared. Enhanced exposure only occurs at wavelengths
and polarizations that exactly match the plasmonic resonances. Hence our
work demonstrates that wavelength selective addressing of hot spots for
nanolithography using an inexpensive, low peak-power picosecond pulsed
source is freely tunable throughout the visible and infrared to match any
desired plasmon resonance.