Double optical limiting in gold nanoshell: tuning from visible to infrared region by shell thickness

Because of surface plasmon resonance (SPR) induced nonlinear absorption, there are two optical limiting bands in gold nanoshells. The longer and shorter wavelength optical limiting bands correspond to the symmetric and antisymmetric coupling resonance absorption modes, respectively. Theoretical calculations based on quasi-static approximation show that the longer wavelength optical limiting band red shifts from the visible to the infrared region by decreasing the shell thickness. A mechanism based on polarization direction of a local electric field in a gold shell is investigated to describe the wavelength shift of the optical limiting band.