Low-loss phononic integrated circuits based on a silicon nitride-lithium niobate platform

TL;DR

This paper introduces a low-loss silicon nitride-lithium niobate platform for phononic integrated circuits, enabling high-Q resonators and low phase noise oscillators for advanced microwave and quantum applications.

Contribution

It develops a novel low-loss PnIC platform with key components like waveguides and resonators, demonstrating a high-performance 1-GHz phononic oscillator.

Findings

Achieved low phase noise of -159.0 dBc/Hz at 100 kHz offset.

Demonstrated high-Q ring resonators and low-loss waveguides.

Established a versatile platform for microwave and quantum phononics.

Abstract

Microwave-frequency acoustic waves in solids have emerged as a versatile platform for both classical and quantum applications. While phononic integrated devices and circuits are being developed on various material platforms, an ideal phononic integrated circuit (PnIC) platform should simultaneously support low-loss waveguide structures, high-quality-factor resonators, high-performance modulators, and efficient electromechanical transducers. Here, we establish a low-loss gigahertz-frequency PnIC platform based on patterned thin-film silicon nitride (SiN) on lithium niobate (LN) substrate. We develop low-loss PnIC building blocks including waveguides, directional couplers, and high-quality-factor (high-Q) ring resonators. As an application, we demonstrate a 1-GHz phononic oscillator based on a ring resonator, reaching a low phase noise of -159.0 dBc/Hz at a 100-kHz offset frequency. Our low-loss PnICs could meet the requirements in microwave acoustics, quantum phononics, and integrated hybrid systems combining phonons, photons, superconducting qubits, and solid-state defects.