Simplified aluminum nitride processing for low-loss integrated photonics and nonlinear optics

Area of Science:

• Materials Science
• Photonics
• Nanotechnology

Background:

• Aluminum nitride (AlN) possesses strong nonlinear optical properties (χ(2) and χ(3)) crucial for integrated photonics.
• Fabricating AlN nanostructures is challenging due to material hardness and charging effects during electron beam lithography, often requiring complex multi-mask processes.

Purpose of the Study:

• To develop a simplified and efficient method for fabricating high-quality AlN microresonators.
• To overcome the limitations of conventional AlN nanofabrication techniques.

Main Methods:

• A novel fabrication approach using a single silicon nitride mask combined with a removable conductive polymer layer.
• The conductive layer facilitates fabrication by simplifying the removal process without additional etching steps.
• Achieved high etching selectivity (4:1) between AlN and the mask material.

Main Results:

• Successfully fabricated AlN microresonators with high intrinsic quality factors (Q) up to 1.0 × 10⁶.
• Demonstrated the capability for mid-infrared photonic device fabrication.
• Observed various nonlinear optical phenomena, including frequency comb generation, Raman lasing, third-harmonic generation, and supercontinuum generation.

Conclusions:

• The developed method offers a simpler and more effective route for AlN microresonator fabrication.
• The high-Q AlN microresonators are suitable for advanced integrated photonic devices and exploring nonlinear optical phenomena.
• This advancement facilitates the development of AlN-based photonic devices for diverse applications.