Broadband Transient Response and Wavelength-Tunable Photoacoustics in Plasmonic Hetero-nanoparticles

The optically driven acoustic modes and nonlinear response of plasmonic nanoparticles are important in many applications, but are strongly resonant, which restricts their excitation to predefined wavelengths. Here, we demonstrate that multilayered spherical plasmonic hetero-nanoparticles, formed by alternating layers of gold and silica, provide a platform for a broadband nonlinear optical response from visible to near-infrared wavelengths. They also act as a tunable optomechanical system with mechanically decoupled layers in which different acoustic modes can be selectively switched on/off by tuning the excitation wavelength. These observations not only expand the knowledge about the internal structure of composite plasmonic nanoparticles but also allow for an additional degree of freedom for controlling their nonlinear optical and mechanical properties.

Automated summary

In this study, the optically driven acoustic modes and nonlinear response of multilayered spherical plasmonic hetero-nanoparticles were investigated. These nanoparticles, composed of alternating layers of gold and silica, exhibited a broadband nonlinear optical response from visible to near-infrared wavelengths. Additionally, they served as a tunable optomechanical system with mechanically decoupled layers, allowing for selective switching of different acoustic modes by tuning the excitation wavelength. These findings not only enhance our understanding of the internal structure of composite plasmonic nanoparticles but also provide an additional degree of freedom for controlling their nonlinear optical and mechanical properties.