Optical reconfiguration and polarization control in semi-continuous gold films close to the percolation threshold

Abstract

Controlling and confining light by exciting plasmons in resonant metallic nanostructures is an essential aspect of many new emerging optical technologies. Here we explore the possibility of controllably reconfiguring the intrinsic optical properties of semi-continuous gold films, by inducing permanent morphological changes with a femtosecond (fs)-pulsed laser above a critical power. Optical transmission spectroscopy measurements show a correlation between the spectra of the morphologically modified films and the wavelength, polarization, and the intensity of the laser used for alteration. In order to understand the modifications induced by 1 arXiv:1704.08550v1 [physics.optics] 27 Apr 2017 the laser writing, we explore the near-field properties of these films with electron energy-loss spectroscopy (EELS). A comparison between our experimental data and full-wave simulations on the exact film morphologies hints toward a restructuring of the intrinsic plasmonic eigenmodes of the metallic film by photothermal effects. We explain these optical changes with a simple model and demonstrate experimentally that laser writing can be used to controllably modify the optical properties of these semi-continuous films. These metal films offer an easy-to-fabricate and scalable platform for technological applications such as molecular sensing and ultra-dense data storage.

Universal mechanical exfoliation of large-area 2D crystals

“…Nevertheless, we show here that the conductivity of Au/Ti adhesion layer can be drastically tuned by controlling its nominal thickness, which demonstrate that both optical measurements and device fabrication can be realized on this one-step exfoliated samples. Figure 4a, b shows that the Au/Ti films become insulating (i.e., electrically discontinuous) if the combined thickness of Ti/Au decreases to 3 nm or below 41 . Our exfoliation method is not apparently limited by the Au thickness, therefore, those largearea 2D crystals are expected to be exfoliated by either conducting or non-conducting Au-coated substrates.…”

Reconfigurable Near‐field Enhancement with Hybrid Metal‐Dielectric Oligomers

“…Therefore, we work in non‐resonant conditions of irradiation and for this case the polarization of the laser beam does not affect the modification process. We should note that the influence of laser beam polarization on the modification process was shown to be critical for thin gold films or asymmetrical nanoantennas with different orientations with respect to the laser beam polarization, but can be neglected for symmetrical nanoantennas …”

Two-dimensional plasmons in the random impedance network model of disordered thin film nanocomposites

“…We would also mention some modern papers that study plasmon resonances in disordered systems via full-wave numerical simulations [53][54][55]. Such an approach requires significant computational resources with respect to impedance network models and thus does not allow studying large-scale properties of resonances in systems near the percolation threshold.…”