Optical Transmission through Al and Mg Nanoapertures

Yunshan Wang Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah, USA Xiaojin Jiao Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah, USA Kanagasundar Appusamy Metallurgical Engineering, University of Utah, Salt Lake City, Utah, USA Sivaraman Guruswamy Metallurgical Engineering, University of Utah, Salt Lake City, Utah, USA Steve Blair Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah, USA

Exploring new materials that can sustain SPPs in the Ultraviolet spectral range has generated a surge of interest recently [1]. One implication is improving the detection limit of biomolecules whose native fluorescence reside in the UV range [2]. Aluminum has emerged as a promising UV SPP material and has been used for fluorescence enhancement [3]. Mg has also been shown to exhibit SPPs in the UV range. Here we present experimental studies of extraordinary optical transmission of Al and Mg nanoaperture arrays in the UV and compare them with FDTD simulation results. The positions of zero order and first order SPP resonant wavelengths have been identified using SPP dispersion relations [4]. Simulations match well with experiment data in terms of the positions of transmittance dips and peaks at large wavelength (250-400nm). Both our experiments and simulations show that for the same period, Mg nanoapertures show about a 50nm red-shift in the positions of transmittance dips compared to Al nanoapertures. In addition, the transmittance is smaller for Mg compared with Al. Our measurements are consistent with the SPP FOM, where the Mg FOM is smaller than Al in the UV range. Nevertheless, our results show that Mg is another promising UV plasmonic material.

Transmission spectrum of Al nanoaperture arrays (top) (periods: 330, 350 and 400nm), and Mg nanohole arrays (bottom) (periods: 280, 300, 330 and 350nm). Thickness is 100nm. Hole diameter is about 120 nm.

Transmission spectrum of Al nanoaperture arrays (top) (periods: 330, 350 and 400nm), and Mg nanohole arrays (bottom) (periods: 280, 300, 330 and 350nm). Thickness is 100nm. Hole diameter is about 120 nm.

Reference

[1] M. McMahon, et al., “Plasmonics in the ultraviolet with the poor metals Al, Ga, In, Sn, Tl, Pb, and Bi." Physical chemistry chemical physics : PCCP, vol. 15, no. 15, pp. 5415-23, 2013

[2] R. Lakowicz, et al., “Intrinsic fluorescence from DNA can be enhanced by metallic particles." Biochemical and biophysical research communications, vol. 286, no. 5, pp. 875-9, 2001.

[3] Rayet al., “Aluminum nanostructured films as substrates for enhanced fluorescence in the ultraviolet-blue spectral region." Analytical chemistry, vol. 79, no. 17, pp. 6480-7, 2007.

[4] J. Garcia-Vidal, et al., “Light passing through subwavelength apertures," Reviews of Modern Physics, vol. 82, no. 1, pp.729-787, 2010.

Blair@ece.utah.edu









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