Abstract

We propose simple-pulse two-step technique for fabrication of different plasmonic nanostructures, including nanorods and nanorings, as well as nanorod-nanoring ensembles on glass substrates. In this technique, a noble metal film, covering a bulk glass substrate, is irradiated by a single tightly focused nanosecond laser pulse, accompanied by slow polishing of the laser-fabricated nanostructures by an accelerated argon ion (Ar⁺) beam. Each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar⁺- ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We have demonstrated that the main geometric parameters of the fabricated NR and nanoring-nanorod ensembles are determined by the pulse energy and the metal film thickness, while the subsequent Ar⁺-ion polishing allows height tuning for the nanostructures. Fabricated FPNs demonstrate both the 8-fold and up to 10³ plasmon-mediated enhancement of the photoluminescence and Surface-enhanced Raman scattering signals from the Rhodamine 6G organic nanosized emitters, respectively. The plasmonic nature of this enhancement was rigorously examined and verified by direct measurements of the dark-field and photoluminescence spectra, as well as by angle-dependent character of the photoluminescence enhancement and supported by numerical calculations of corresponding electromagnetic near-fields and Purcell factor.

© 2016 Optical Society of America