Ultrafast optical heating induced polarization-dependent optical switching in gold nanowires

Abstract

Excitation using femtosecond laser pulses induced ultrafast heating of discontinuous gold nanowires, resulting in transient thermal expansion of the gold nanostructures that constitute the nanowires. The cross-plasmon resulting from the closely arranged gold nanostructures along the nanowires was modified by the change in the small gaps due to the thermal effect. This led to the spectral shift of the cross-plasmon resonance and laid the photophysical basis for the optical switching. A femtosecond pump-probe scheme was used to investigate the ultrafast optical switching dynamics. The most efficient optical switching effect was observed when the pump and probe laser pulses were polarized perpendicular and parallel to the discontinuous gold nanowires, respectively.