Light absorption efficiencies of gold nanoellipsoid at different resonance frequency

Light absorption efficiencies (defined as the ratio of the absorption cross section to the total extinction cross section at each resonance wavelength) of gold nanodisk and nanorod were calculated based on quasi-static approximation. The absorption efficiency solely depends on the frequency of surface plasmon resonance. With increasing resonance wavelength, the absorption efficiencies change in the same fashion for both nanodisk and nanorod. However, the resonance absorption at short wavelength is easy to be obtained by gold nanodisk, whereas the resonance absorption at longer wavelength is easy to be obtained by gold nanorod. High absorption efficiency (>98%) can be obtained in the visible region by increasing the aspect ratio of gold nanodisk. Although the longitudinal absorption efficiency of gold nanorod is relative lower by increasing the aspect ratio, the absorption efficiency is also tunable in the near infrared region, which makes it potentially useful in silicon solar cells and vivo applications.