Saturable and Reverse Saturable Scattering of a Single Gold Nanoparticle

Nowadays, nonlinear optics plays an unprecedented role in research not only because of its intriguing physical mechanisms but the wide range of photonic functionalities, such as frequency generation, ultrafast signal processing, microscopy, etc. [1]. However, optical nonlinearities are usually weak. One of the most promising candidates is the nonlinearity of localized surface plasmon resonance (LSPR) in noble metal nanostructure. The strongly enhanced nonlinearity is usually attributed to the strong surface field enhancement due to the nanometer scale and the interband transitions near visible light. Many examples had been discovered, such as Kerr effect [2], saturable and reverse-saturable absorption (SA and RSA) [3].