Linear Arrays of Metal-Coated Microspheres: a Polarization-Sensitive Hybrid Colloidal Plasmonic-Photonic Crystal

TL;DR

This study investigates the optical properties of a linear array of metal-coated microspheres forming a hybrid colloidal plasmonic-photonic crystal, revealing polarization-sensitive effects and spectral tunability for potential sensing applications.

Contribution

It provides detailed experimental and simulated analysis of hybrid modes and polarization effects in a novel linear plasmonic-photonic crystal structure.

Findings

Identification of propagative hybrid and localized surface plasmon modes.

Spectral tunability depends on sphere diameter and grating period.

The structure exhibits polarization-sensitive surface-enhanced Raman scattering.

Abstract

Colloidal plasmonic-photonic crystals represent a class of hybrid materials composed of a dielectric colloidal spheres photonic lattice and a metal plasmonic film. In this work, the optical properties of a linear array colloidal plasmonic-photonic crystal consisting of silver films deposited over linear arrays of polystyrene microspheres are analysed in detail. Experimental and simulated optical transmittance and reflectance spectra both with unpolarized and polarized light are used to investigate the optical response of the linear plasmonic-photonic crystal. Among the various photonic/plasmonic modes observed, the existence of both propagative plasmonic-photonic hybrid mode and localized surface plasmon mode can be mentioned. The spectral tunability of these structures is highlighted by studying the dependence of the optical response on geometrical parameters such as sphere diameter and grating period. Finally, the linear plasmonic-photonic crystal exhibits a polarization-selective surface-enhanced Raman scattering effect, making them of interest for both fundamental studies and development of applications based on surface-enhanced Raman spectroscopy or surface-enhanced fluorescence.