Broadband photonic crystal waveguide 60 degrees bend obtained utilizing topology optimization

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• Planar photonic crystal waveguides are crucial for integrated optical circuits.
• Achieving wide bandwidth and low loss in waveguide bends remains a challenge.

Purpose of the Study:

• To design a highly efficient 60-degree bend for single-mode planar photonic crystal waveguides.
• To achieve a record transmission bandwidth in silicon-on-insulator (SOI) material.

Main Methods:

• Utilized topology optimization for waveguide bend design.
• Fabricated the designed waveguide in silicon-on-insulator.
• Characterized transmission bandwidth and bend loss for TE polarization.

Main Results:

• Demonstrated a 60-degree bend in a single-mode planar photonic crystal waveguide.
• Achieved a record-breaking 200-nm transmission bandwidth.
• Measured an average bend loss of 0.43+/-0.27 dB for TE polarization.
• Experimental results showed good agreement with 3D finite-difference-time-domain (FDTD) simulations.

Conclusions:

• Topology optimization is effective for designing high-performance photonic integrated components.
• The demonstrated device pushes the boundaries for bandwidth in photonic crystal waveguide bends.
• The results validate the design approach for future integrated photonic applications.