Optical nonlinearities from transverse plasmon resonance in gold nano-rods

摘要

The nonlinear refraction of two gold nano-rods with different sizes was investigated by using Z-scan technique with nanosecond pulses at 532 nm. Their optical limiting (OL) effect was also studied at the wavelength. The experimental results show that they possess strong optical nonlinearities when excited near the transverse plasmon resonance, depending critically on the size of nano-rods. The nonlinear refractions arise mainly from the strong excited-state nonlinearity of conduction band electrons. In contrast, the OL effect originates from the transverse plasmon resonance absorption, excited-state absorption and absorption-induced nonlinear scattering.