Nonlinear terahertz effects of gold nanofilms

Nonlinear interaction between strong-field terahertz electromagnetic waves and matters will become one of the next hot research frontiers in nonlinear optics. However, lack strong radiation sources appropriate materials have impeded its progress. Here we systematically investigated effects gold (Au) nanofilms on different substrates, including SiO 2 , high-resistivity Si -high-resistivity hybrid substrates. The are emitted from lithium niobate crystals via tilted pulse front technique, obvious transmission responses observed along with varying incident field strengths for all Au samples three types behavior is enhanced when nanofilm thickness increases, which can be qualitatively understood by introducing quantum tunneling effect carrier multiplication theory generated at nano-slits under illumination pulses. Our demonstrations not only open a new paradigm investigations future high-speed devices, but also provide an effective platform exploring extreme sciences.