Abstract
Materials with large third-order optical nonlinearity and ultra-fast response time are important for future applications in a number of fields, such as optical telecommunications, data storage, optical computation and information processing. Nano-sized gold and silver composite materials have attracted much attention because of their high nonlinear susceptibilities due to local field enhancement near the surface plasmon resonance (SPR). However, these high susceptibilities are only observed at the SPR wavelength (around 530 and 400 nm for Au and Ag, respectively), and decrease dramatically at wavelengths far from the SPR position, which limits the practical applications of these materials. Simple materials exhibiting high nonlinearity and fast response speed at multiple frequencies, if developed, would be ideal for novel multi-mode optical devices. Here, we demonstrate a simple strategy for self-assembling amorphous SiO2-coated linear-chains of gold nanoparticles (so-called nanochains) on glass substrates for multi-mode nonlinear optical switches.
