Light controlled dynamic hotspots on plasmonic surface utilizing plasmonic snowman arrays

Abstract

In recent time, plasmon enhanced nanostructures, plasmonic arrays, and plasmonic meta-surfaces have gained utmost importance owing to their diverse applications in a wide range of fields that include biomedical engineering, surface enhanced Raman spectroscopy, photo-thermal, and more. Despite the advancement of nanofabrication technology, utilization of trivial fabrication techniques is equally important considering cost of fabrication and field of applications. In the present work, we simulate simpler plasmonic nano-structures for creating dynamic hotspots on a single plasmonic surface utilizing combinations of gold disks of different sizes. The gold disks of progressively diminishing sizes are brought in close proximity to make an array which we named as plasmonic snowman (PSM) array. Briefly, the article focuses on studying unique plasmonic characteristics of PSM array based plasmonic surfaces. The PSM array surfaces have multiple nano-gaps wherein on demand plasmonic hotspots can be created by controlling, size of the disks, wavelength of the background light, polarization of light, and the spatial arrangement of PSM arrays. The size and arrangement of the gold nano-disks decide the resonance wavelength and thereby most desirable operational wavelength. In this study, four different types of PSM arrangements are created for showcasing on demand tuning of plasmonic hotspots. The appearance of active hotspots for the proposed structures have been explored in detail. The effect of PSM array orientation, polarization of background, and plasmonic couplings are the major contributing parameters for controlling the positions of multiple hotspots on the proposed plasmonic surfaces. These tunable hotspots are capable of offering diverse bio-sensing and wearable electronics applications.