Fractal tree plasmonic nanoantenna array for multispectral surface-enhanced spectroscopy

Plasmonic nanoantenna are pushing the sensitivity and detection limits of chemical and biochemical assay technologies. The challenge is to precisely tailor the spectral lineshapes and operational bandwidth and to engineer the localized electromagnetic field enhancements ('hot spots') optimally for a particular spectroscopic task. Here we present a numerical study of the optical behavior of ternary tree fractal plasmonic gold nanoantenna. Spectral features spanning the visible to mid IR range are seen with the observation of characteristic self-similar features as the fractal order increases. The geometrical regularity of the ternary tree is perturbed and its influence on the optical properties is studied. The nanoantenna is seen to exhibit reduced polarization sensitivity even in highly assymetric structures. The intriguing optical properties of ternary tree fractal nanoantenna are particularly promising for the optimal design of substrates for performing multispectral surface-enhanced spectroscopy.