Surface Plasmon-enhanced Light Absorption in Au Nanohole Array with Optical Cavity

The light absorption in Au nanohole array with optical cavity is optimized by using finite-difference time-domain (FDTD) simulation. First, the transmission and reflection spectrums from an Au nanohole array, as well as the near field profiles at its surface, indicate that the strongest surface plasmon resonance occurs at approximately 672nm. Then, the comparison between the devices with and without nanohole array shows that half of the incident light energy can be absorbed owing to the surface plasmon-enhanced field confinement. Finally, an optical cavity, which has a thickness of 52nm, only one tenth of the wavelength, is designed to further improve the light absorption of the device. Therefore, the optimized device has greater field enhancement property, which creates 98.82% light absorption in 672nm.