Four-mode parallel silicon multimode waveguide crossing scheme based on the asymmetric directional couplers

Area of Science:

• Photonics
• Integrated Optics
• Optical Communications

Background:

• Mode division multiplexing (MDM) is crucial for increasing optical communication capacity.
• On-chip waveguide crossings are essential components for densely integrated photonic circuits.
• Existing crossing designs often suffer from large footprints and high crosstalk.

Purpose of the Study:

• To propose and demonstrate a novel ultra-compact four-mode silicon waveguide crossing device.
• To enable densely integrated on-chip mode division multiplexing systems.
• To achieve efficient mode dropping and crossing with minimal area.

Main Methods:

• Theoretical proposal and experimental demonstration of a parallel crossing scheme.
• Utilizing asymmetric directional couplers (ADCs) for mode manipulation.
• Optimizing ADC structural parameters using particle swarm optimization.

Main Results:

• Achieved insertion losses below 0.5 dB at 1550 nm.
• Demonstrated crosstalk levels below -20 dB across a broadband (1530-1580 nm).
• Realized an ultra-compact footprint of 25 × 70 µm².

Conclusions:

• The proposed device offers a highly efficient and compact solution for on-chip MDM.
• The design is scalable for accommodating more modes by cascading ADCs.
• This technology facilitates denser integration for future optical communication systems.