Wavelength-dependent nonlinear absorption of gold nanocages
The dipole resonances of gold nanocages were investigated theoretically using finite difference time domain (FDTD). The results show that field enhancement is obtained at the walls of the gold nanocages. It is believed that the effect can cause strong optical nonlinear property. To test the hypothesis, the nonlinear absorption was investigated using broadband 5ns Z-scan. It was found that, at low intensities the sample shows saturation absorption (SA), while at higher intensities, a switch from SA to reverse saturation absorption (RSA) occurs. Moreover, the nonlinear absorption of sample is sensitively wavelength-dependent, and in resonant region saturation intensity is the largest.
Gao Yachen,Shuang Chen,Suying Yang,Huang Yan,Weiyan Jiao,Guanghua Fan. Wavelength-dependent nonlinear absorption of gold nanocages[J].Chinese Optics Letters,2020,18(1):01.