Abstract

An $\mathrm{Ag}/{\mathrm{SiO}}_2/\mathrm{Ag}$ sandwich delta nanostar with three sharp angles (30°) is proposed. The extinction efficiency property with a variation in environment refractive index has been investigated in detail by the finite difference time domain method. The refractive index response sensitivity is $482.67\mathrm{nm}/\mathrm{RIU}$. And the correlations between resonance wavelengths and thickness of the dielectric layer are also established. It reveals that as the thickness increases, the peak wavelength turns to red shift, and a tunable resonance wavelength is achieved through the thickness adjusting of the ${\mathrm{SiO}}_2$ layer. The maximum of the electric field enhancement is 833.776 with the thickness of the dielectric layer $h=40\mathrm{nm}$. Moreover, the influence of the vertex truncation on the extinction spectra and the refractive index sensitivity has also been analyzed.

© 2014 Optical Society of America

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