Low-loss 3-dimensional waveguide crossing with a parabolic taper interlayer coupler based on a SiN-SiN-Si three-layer...

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Integrated photonics relies on efficient waveguide crossings.
• Minimizing loss and crosstalk in multi-layer waveguides is crucial for device performance.

Purpose of the Study:

• To demonstrate a low-loss SiN-SiN-Si three-layer silicon waveguide crossing.
• To develop an efficient interlayer coupler for multi-layer photonic integrated circuits.

Main Methods:

• Fabrication of a SiN-SiN-Si three-layer silicon waveguide structure.
• Utilized a parabolic interlayer coupling design to reduce loss and length.
• Characterization of waveguide crossing loss, crosstalk, and interlayer coupling loss across a specific wavelength range.

Main Results:

• Achieved ultra-low loss (<0.82/1.16 mdB) and crosstalk (<-56/-48 dB) for underpass and overpass crossings.
• Demonstrated a record-low interlayer coupling loss (<0.11 dB) for the SiN-SiN-Si platform.
• Reduced the total interlayer coupler length to 120 µm.

Conclusions:

• The developed SiN-SiN-Si waveguide crossing offers superior performance for integrated photonics.
• The parabolic interlayer coupler design is effective in minimizing loss and footprint.
• This technology enables more complex and efficient photonic integrated circuits.