Topography Tuning for Plasmonic Color Enhancement via Picosecond Laser Bursts

摘要

The tuning of 3D topographical features on silver for the production ofrnplasmonic colors is reported. The topography is produced by applyingrnclosely time-spaced laser bursts. Using laser bursts increases the Chromarnof the colors produced by up to 100% compared to the nonburst coloringrnmethod. By adjusting the energy distribution of the laser pulses in a burst,rnwhile maintaining the total burst energy constant, significantly differentrncolor palettes and topographical structures are produced. Scanning electronrnmicroscope analysis of the surfaces produced reveals the creation of threerndistinct sets of laser-induced periodic-like surface structures (LIPSS): lowrnspatial frequency LIPSS (LSFL), high spatial frequency LIPSS (HSFL), andrnlarge LIPSS that have a period about 7× that of the laser wavelength. Twotemperaturernmodel simulations of silver irradiated by a laser burst show arnsignificant increase in the electron–phonon coupling which is mainly responsiblernfor the creation of LIPSS. Finite-difference time-domain simulations ofrna model of the surface, consisting of nanoparticles arranged on a sinusoidalmodulatedrnsurface of varying amplitude (0 to 150 nm) and period (200 andrn1000 nm), elucidate the importance of the HSFL and LSFL structures forrncolor formation, including the increase in Chroma (saturation) observedrnexperimentally.