Wavelength-dependent nonlinear optical properties of hexagonal gold nanoparticles and its application in pulsed lasers

Abstract

We have studied the nonlinear refractive index, saturation absorption characteristics, and ultrafast carrier dynamics of hexagonal gold nanoparticles at broadband. By leveraging Z-scan technique and time-resolved transient absorption spectroscopy, we unveil the nonlinear optical behavior of gold nanoparticles and quantitatively determine their nonlinear parameters. Our experimental results underscore the prominent nonlinear optical effects exhibited by gold nanoparticles under intense electromagnetic fields, encompassing saturation absorption (SA) and self-focusing phenomena. Notably, the ultrafast carrier dynamics of gold nanoparticles are found to be strongly influenced by probe wavelength. We further studied the passively Q-switched pulse lasers generation using gold hexagonal nanoparticles as saturated absorbent at 1064 nm and 2800 nm. These findings not only deepen our understanding of the nonlinear optical properties of gold nanoparticles but also offer valuable insights for the development of novel nonlinear optical devices and applications.