Fluorescent emission enhancement by aluminium nanoantenna arrays in the near UV

Abstract

In this paper, we demonstrate fluorescence enhancement of a laser dye, using aluminium nanoantenna arrays designed for the near UV range. A series of nanorod arrays were fabricated by focused ion beam milling then spin-coated with a dye with an intrinsic quantum yield in the range 0.5-0.6. Scanning confocal photoluminescence measurements of the arrays show up to 1.9x enhancement of the fluorescence signal compared to the reference on glass. The observed near UV fluorescence enhancement is affected by the relatively high intrinsic quantum yield of the dye and coupling to an array mode. FDTD modelling predicts strong dependence of the emission on angle, with maximum emission at high angles with respect to normal. The model predicts that using a lens with a numerical aperture of 0.9 would lead to an enhancement of up to ~6x enhancement.

Enhanced UV/blue fluorescent sensing using metal-dielectric-metal aperture nanoantenna arrays

“…5 (a). The narrow enhancement spectrum of MDM antenna arrays compared with the MDM single cell is due to the coupling between the antenna elements [10]. As can see in Fig.…”

“…In the context of fluorescent biosensing applications, plasmonic nanoantennas can create highly enhanced local fields when pumped resonantly, and through Purcell enhancement can significantly enhance fluorescent emission, both of which can improve fluorescence based sensors [25][26][27]. Recently we have shown fluorescent emission enhancement using aluminium nanoantenna arrays in the near-UV [10]. Scanning confocal photoluminescence measurements of the arrays showed up to 1.9 times more enhancement of the fluorescent signal compared to a reference on glass.…”

“…The concept of surface plasmons or plasmonics has seen widespread use in implementing optical devices and photonic circuits [1][2][3] as well as in chemical sensing technologies [4][5][6][7][8]. Recent advances in metallic nanoparticle synthesis and nanofabrication methods have led to a variety of new nanostructures composed of nanoparticles, nanoholes, and other structures with precisely controlled shapes, sizes, and/or spacers, with novel physical and chemical properties [9][10][11][12]. Such exquisite fabrication and synthesis control in combination with advances in theory and the emergence of quantitative electromagnetic simulation tools has provided a better understanding of the optical properties of single and coupled metallic nanostructures of various sizes and shapes [10,11].…”

“…Recent advances in metallic nanoparticle synthesis and nanofabrication methods have led to a variety of new nanostructures composed of nanoparticles, nanoholes, and other structures with precisely controlled shapes, sizes, and/or spacers, with novel physical and chemical properties [9][10][11][12]. Such exquisite fabrication and synthesis control in combination with advances in theory and the emergence of quantitative electromagnetic simulation tools has provided a better understanding of the optical properties of single and coupled metallic nanostructures of various sizes and shapes [10,11]. Various approaches for modifying metallic surfaces and structures make it possible to effect the selective binding and detection of specific targets for chemical and biological sensing.…”

“…We simulated the enhancement with the FDTD method using electric dipoles placed inside the subwavelength aperture arrays. The simulated enhancement definition here is a very simple one which is the ratio of total emitted power from a dipole with and without the antenna which does not account for the very strong focusing effects that occur due the periodic nature of the array [10]. In addition, we study the influence of antenna parameters such as silica gap thickness, aperture size and shape, and also position of the electric dipole sources on the fluorescent enhancement.…”