Plasmonic enhancement of surface acoustic wave – photonic devices in silicon-on-insulator

Silicon photonic devices are primarily designed for optical communication in data centers, but they also find applications in sensing and signal processing. True time delays of waveforms on-chip is a primary building block of signal processing systems. However, the delay of electromagnetic waves in small footprint is difficult due to their high velocity. To address this, our group has developed a platform leveraging surface acoustic waves (SAWs) in standard silicon-on-insulator layers, where SAWs are generated through thermo-elastic absorption in metallic gratings. This platform has been applied to integrated microwave-photonic filters, thin-layer analysis, and electro-opto-mechanical oscillators. Despite its potential, the thermo-elastic actuation mechanism is comparatively inefficient, causing significant radio-frequency power losses of about 70 dB.
My doctoral research aims to reduce these losses by three orders of magnitude using plasmonic resonance absorption. By replacing uniform metallic stripes with periodic unit cells designed for plasmonic resonance at 1550 nm, we aim to enhance optical absorption, generating stronger acoustic waves and improving power transmission. Preliminary results already demonstrate a 20 dB improvement. We demonstrate the benefit of lower losses in electro-opto-mechanical oscillators with narrower linewidth, lower phase noise, and better side-mode suppression.
Additionally, I aim to develop silicon-photonic sensors for hydrogen detection, a critical step for hydrogen's adoption as a fossil fuel alternative. By integrating a palladium layer along SAW pathways, we exploit changes in mechanical properties due to hydrogen absorption to detect its presence. This concept builds on my M.Sc. work in thin-layer analysis, now extended towards scalable, silicon-based hydrogen sensors.

PhD. student under the supervision of Prof. Avi Zadok.