Hydrogen-regulated dynamic plasmonic Fano resonances

Abstract

The unique properties of plasmonic Fano resonances have drawn extraordinary attention owing to their potential for interesting applications in biochemical sensing, slow light devices, near-field enhancement, and active plasmonics. Recent experiments have demonstrated that Fano resonances can be generated from a plasmonic nanocluster (nano-blossom) due to the destructive interference of the superradiant and subradiant modes [1]. Such Fano resonances can be tailored by varying the relative dimensions of the central and peripheral disks [1] as well as be switched on and off by replacing the center disk with a semicircle or by rotating the polarization of the incident light [2]. In this work, we demonstrate a novel plasmonic Fano system, which can be actively regulated by hydrogen. The structure comprises magnesium (Mg) and gold (Au) nanoparticles (see Figure 1a). The active functionality is enabled due to the fact that Mg nanoparticles can undergo a phase transition from metallic (Mg) to dielectric state (MgH 2 ) when absorbing hydrogen [3,4]. Importantly, the process is fully reversible upon oxygen exposure.