Pre-patterned Freestanding Single-crystalline Lithium Niobate Photonic Components for Advanced Quantum Photonic Integrated Circuits

Lithium niobate (LN), first synthesized 70-years ago, is highly valued in photonics for its excellent material properties and ability to facilitate frequency mixing across a broad spectrum, from gigahertz to petahertz frequencies. Recently, the commercial availability of thin-film LN has revitalized interest in the material due to its ability to promote tight mode confinement, thereby enhancing frequency-mixing efficiency and enabling new avenues for optical property optimization, such as dispersion engineering.

This project seeks to develop pre-patterned freestanding single-crystalline LN photonic components for advanced quantum photonic integrated circuits. These components will serve as core elements in visible light communication platforms, offering superior performance compared to conventional materials. This work addresses significant challenges in the fabrication of thin-film LN, such as overcoming limitations of the smart-cut process and improving etching techniques.

By advancing the integration of high-quality LN films, this project will promote scientific progress, enhance national technological capabilities, and support educational and diversity initiatives by involving K-12 and college-level students in hands-on experiments and workshops. This project will also benefit society by paving the way for advanced quantum photonics and communication technologies.

This project aims to develop pre-patterned freestanding single-crystalline LN photonic components to address the limitations of conventional LN fabrication techniques. The PI’s team has demonstrated a universal mechanical exfoliation method to produce freestanding single-crystalline membranes from complex-oxide materials. This project will build on that foundation to develop selective epitaxy of LN on pre-patterned substrates, achieving 100% yield exfoliation of damage-free LN waveguide patterns, and integrating these waveguides into photonic circuits for visible wavelength communication.

Throughout the development, the project will precisely engineer photonic components to meet the stringent requirements of quantum photonics. Additionally, the team will optimize wafer-scale tailoring technology for high-density photonic components, advancing large-area quantum photonic platforms. Successful implementation of this technology will have a significant impact on the quantum photonics community by enabling damage-free, ultra-thin LN photonic components for visible wavelength communication.

This addresses major limitations of conventional waveguides, such as poor optical confinement due to narrow bending radius and limited modulation capabilities. The project will also pioneer hybrid integration strategies for multiple photonic components, fostering unconventional functionalities and geometries in integrated platforms. Ultimately, this research will innovate photonic integration technology, advancing quantum processing and networking.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.