Ultrafast photochromism and bacteriochromism in one dimensional hybrid plasmonic photonic structures

Abstract

Hybrid plasmonic photonic structures combine the plasmonic response with the photonic band gap, holding promise for utilization as optical switches and sensors. Here, we demonstrate the active modulation of the optical response in such structures with two different external stimuli, e.g. laser pulses and bacteria.First, we report the fabrication of a miniaturized (5 x 5 mm) indium tin oxide (ITO) grating employing femtosecond laser micromachining, and we show the possibility to modulate the photonic band gap in the visible via ultrafast photoexcitation in the infrared part of the spectrum. Note that the demonstrated time response in the picosecond range of the spectral modulation have an industrial relevance.Moreover, we manufacture one-dimensional photonic crystals consisting of a solution-processed dielectric Bragg stack exposing a top-layer of bio-active silver. We assign the bacterial responsivity of the system to polarization charges at the Ag/bacterium interface, giving rise to an overall blue shift of the photonic band gap.

Stimuli-Responsive Photonic Crystals

“…Recently, silver has been integrated inside 1D PhCs in order to exploit its antibacterial properties and detect the presence of bacteria [27,75,[115][116][117]. Paternò et al fabricated a hybrid plasmonic-photonic device applying a silver layer on top of a TiO 2 /SiO 2 PhC.…”

“…Incorporating a photosensitive material [75,[118][119][120] or a dye [77,121] inside a photonic crystal structure allows for tuning of its optical properties upon exposure to light stimuli. Light can change the refractive index or lead to a modification of the structural properties.…”