Study of plasmonics induced optical absorption enhancement of Au embedded in titanium dioxide nanohole arrays

Abstract

The light absorbing performance of titanium dioxide (TiO2) nanohole arrays partially filled with metallic gold is investigated using analytical methods. As a plasmonic generation element on one-dimensional (1D) TiO2, the shape and distribution of Au nanoparticles can be microfabricated controllably in 1D TiO2 nanohole arrays rather than randomly loaded on their top surface. Results indicate that strong absorption enhancement and a large reception angle in the visible light region (λ = 700 - 850 nm) are induced due to the waveguide coupling within the nanohole arrays and surface plasmonic resonance (SPR) at the interface between TiO2 and gold fillings. By varying the thickness of TiO2 array or gold disks and the periodicity of nanohole array, a significant difference in plasmonic resonance wavelength and light absorption enhancement can be expected. Due to the symmetric configuration of the nanohole structure, the enhancement is insensitive to the polarization of the incoming light and the same enhancement factor can be achieved for both transverse electric (TE) and transverse magnetic (TM) modes. This model offers an approach to precisely control a 1D nanomaterial based plasmonic effect and can be adapted to other materials used in microelectromechanical systems industry.