Heterogeneous lithium niobate photonics on silicon substrates

Area of Science:

• Integrated photonics
• Materials science
• Optoelectronics

Background:

• Lithium niobate (LiNbO3) is a key material for photonic devices due to its electro-optic properties.
• Integrating lithium niobate onto silicon substrates presents significant fabrication challenges.
• Existing methods often struggle with device performance and scalability.

Purpose of the Study:

• To establish a robust platform for fabricating high-performance lithium niobate photonic devices on silicon.
• To demonstrate the capabilities of this platform using essential photonic components.
• To advance heterogeneous integration for next-generation photonic circuits.

Main Methods:

• Utilized wafer bonding techniques to integrate lithium niobate layers onto silicon.
• Employed selective oxidation of refractory metals for precise device confinement.
• Fabricated and characterized lithium niobate microring resonators and Mach-Zehnder modulators.

Main Results:

• Achieved a quality factor of approximately 7.2 × 10⁴ in the fabricated microresonators.
• Demonstrated Mach-Zehnder modulators with a low half-wave voltage-length product of 4 V.cm.
• Measured an excellent extinction ratio of 20 dB for the optical modulators.

Conclusions:

• The developed wafer bonding and selective oxidation platform enables high-performance lithium niobate photonics on silicon.
• This heterogeneous integration approach is suitable for realizing advanced photonic devices and circuits.
• The demonstrated device performance highlights the potential for scalable lithium niobate-based integrated optics.