Electro-Acoustic Modulation of Surface Acoustic Waves on Thin-Film Lithium Niobate Substrate

Abstract

Surface Acoustic Waves (SAWs) are an important physical phenomenon that could allow for universal coupling between solid state systems such as two-level quantum systems, and for applications in modern high-data rate signal processing. Their slow propagation speed, inability to disperse to vacuum and ability to be used on-chip with piezoelectric materials results in SAWs being an attractive alternative to photons and photon-coupling of such systems. Lithium Niobate (LN) is an appropriate material for this use. The high piezoelectric coupling coefficient, demonstrated non-linear effects, and well-established fabrication techniques make Lithium Niobate (LN) an ideal material for use with SAWs. Current passive SAW devices still present challenges. It is currently not possible to couple and drive different isolated two-level quantum systems without active SAW modulation, and current passive SAW filters do not allow for as versatile signal processing as active SAW modulation would. This project demonstrates active electro-acoustic modulation on an LN platform with a fabricated prototype device. More specifically, I design, simulate and fabricate structures on an LN substrate that demonstrate SAW amplitude modulation with a dynamic range of 4 dB, and 180° phase modulation, which can be controlled to give a frequency shift. I also design a benchtop control mechanism for the device.