Dispersion Engineering of Silicon Nitride Microresonators via Reconstructable SU-8 Polymer Cladding

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• Waveguide dispersion is a critical parameter in photonic integrated circuits, influencing signal propagation and device performance.
• Existing methods for dispersion engineering often lack flexibility or require complex fabrication processes.

Purpose of the Study:

• To introduce a novel and flexible approach for engineering waveguide dispersion in microresonators.
• To demonstrate the tunability of waveguide dispersion by patterning the cladding layers.

Main Methods:

• Fabrication of silicon nitride waveguides with different cladding materials (air, oxide, SU-8 polymer).
• Experimental characterization and comparison of waveguide dispersion for each cladding configuration.
• Utilizing a polymer stripping process to reversibly tune dispersion.

Main Results:

• Demonstrated tunable waveguide dispersion ranging from -143 to -257 ps/nm/km by integrating SU-8 polymer cladding.
• Successfully reconstructed the original waveguide dispersion by removing the polymer cladding without degrading resonator quality factor.
• Showcased the potential for precise dispersion control in integrated photonic circuits.

Conclusions:

• Patterning microresonator cladding offers a flexible and effective method for waveguide dispersion engineering.
• This technique enables dynamic tuning of dispersion in both normal and anomalous regimes.
• The developed approach is compatible with standard fabrication processes and preserves device performance.