ECE Seminar - Acoustic wave microsystems for chip-scale RF and optical signal processing

Abstract: Acoustic waves are well-suited for a variety of signal processing applications including RF filtering and optical modulation. Advances in material and fabrication capabilities have enabled the demonstration of chip-scale subsystems in which phonons can exhibit strong interactions with a variety of other physical domains. This talk will discuss progress in the areas of acousto-electric (AE) amplification and acousto-optic (AO) modulation as well as present the development of a phononic integrated circuit platform.
Recently, non-reciprocal and switchable delay lines have generated great interest for applications in full duplex radio networks. As a result, AE-based approaches to mitigating signal interference in the RF front end have been sought. Here we will consider the use of bonding processes for integrating thin film silicon on bulk lithium niobate to produce strong non-reciprocity. These results are developed with regard to implementation in analog correlators and circulators.
Next, we will discuss the development of piezoelectrically-actuated AO modulators in the aluminum nitride (AlN) material system. Optical coupling to AlN thin films is demonstrated in the telecommunications bands, enabling monolithic integration of photonic and bulk acoustic resonators. Overlap of these fields enables efficient conversion from RF to optical frequencies, with applications in integrated microwave photonics and quantum information transfer.
Finally, we will present the development of phononic integrated circuits (PnICs) in scandium-doped aluminum nitride thin films on sapphire substrates. Here we demonstrate wavelength-scale confinement of guided surface acoustic waves to generate a library of components including bent waveguides, splitters and directional couplers. The integration of PnICs with AE and AO effects will thus pave the way for a new class of robust hybrid acoustic microsystems for communications and information processing.