Plasmonic Control of High Energy Ligh-Materials Interaction

Thermoplasmoncis offers an unprecedented potential for creating optically induced heat sources at the nanoscale. Importantly, by creating nanoscale structures heat transfer and related heat induced processed can be efficiently controlled. Here, we study experimentally and theoretically the effects of intense laser beams interaction with plasmonic nanostructures in the ablation regime. Specifically, at high laser beam fluences we create ablation plasmas and study their properties as a function of the underlying plasmonic nanostructure. Our work hints the possibility of controlling ablation plasmas with properly selected and structured thermoplasmonic systems, offering new opportunities for a range of applications from compact accelerators to additive and emerging manufacturing to plasma medicine.<br/>To investigate laser driven ablation we study pulsed (5-50 ns) high energy laser (1064 nm, 10 mJ- 1J) interaction with plasmonic nanostructures. Upon focusing we observe formation of short lived plasmas, which we measure characterize with short gate time ICCD camera to produce time resolved images of the plasma plume and emission spectra with resolution down to 3 ns. With this approach we determine the temporal evolution of ablation plasma temperature, ionization state and its density. We then compare measured ablation dynamics for bulk metals (such as copper, aluminum, and steel) with micro and nanostructured metals (such as thin ~100 nm films). We show that the ablation dynamics for these systems is drastically different, which signifies that by nanostructuring heat generation and transfer are modified. To reveal the complex light materials interaction we develop a theoretical framework that couples optical absorption together with heat transfer and associated series of phase changes. Influence of fast nanosecond evolution and nanoscale interaction in structured plasmonic materials is discussed.