Surface-Acoustic Waves Actuated Amplification in a Plasmonic Waveguide

In this work, we first experimentally show the effect of voltage controlled surface acoustic waves on localized surface Plasmon (LSP), which unveils exceptional properties of plasmon-phonon interaction. The experiment was conducted by depositing Au nanoparticles on an X-cut LiNbO
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to generate plasmonic oscillation, and fabricating an interdigital transducer monolithically to create surface acoustic wave pulses. The interaction between amplitude acoustic wave and plasmonic oscillation affects different plasmon dynamics and relaxation gradients, leading to a systematic change in LSP absorption. Based on the experimental results of plasmonic-phonon interactions, we next propose a new method to amplify the propagating plasmons through an external on-chip surface acoustic signal. We increase the plasmonic intensity gain of 1.08 dB by providing an external excitation in the form of SAW at a peak-to-peak potential swing of 3V, utilizing a single chip.