Flexible Plasmonics.pdf

Researchers studied shape-altering flexible plasmonics of in-situ deformable nanorings. The team, including Wei Tao, Florian Laible, Abdelhamid Hmima, Thomas Maurer, and Monika Fleischer, from the Institute for Applied Physics and Center LISA+ at Eberhard Karls University Tübingen and the Laboratory Light, Nanomaterials and Nanotechnologies at the University of Technology of Troyes, investigated the properties of disc arrays and nanorings on various substrates.

The team fabricated disc arrays on a rigid substrate with increasing sizes and characterized their dark-field reflection spectra. They observed a clear redshift of the dipolar plasmonic disc mode and a broader mode corresponding to the Bragg grating mode. The Bragg mode's position depends on the refractive index of the medium and the lattice period, and its spectral behavior is consistent with literature.

The researchers also fabricated a nanoring (NR) array on a flexible substrate, polydimethylsiloxane (PDMS), and performed scanning electron microscopy (SEM) tests to illustrate the shape-altering of the NRs under strain. They observed a clear shape-altering from circular to elliptical NRs due to the applied strain.

To simulate the dark-field spectra of a single NR structure, the team used two strategies: single-beam s-polarized incidence and normal incidence. They observed a peak at ~1050 nm corresponding to a typical dipolar bonding ring mode and two LSPR modes under single-beam s-polarization.

The researchers also simulated the spectral behavior of the NR array under strain, considering uniform strain-induced periodicity variations and the elastic model of PDMS. They performed separate simulations for deformed arrays with either deformed NRs or undeformed NRs and made assumptions about the simulation studies, including the introduction of a single s-polarized beam and the unchanged thickness of the NRs under strain.

The team quantitatively approximated the shape-altering of a single NR within its array using equations and qualitatively depicted it in figures. The study provides insights into the properties of shape-altering flexible plasmonics of in-situ deformable nanorings and their potential applications.