Low-loss and low-cross talk polarization-insensitive multimode silicon waveguide crossing

Area of Science:

• Photonics
• Integrated Optics
• Materials Science

Background:

• Silicon photonics is crucial for optical communication.
• Waveguide crossings are essential components in integrated photonic circuits.
• Achieving polarization-insensitivity and low loss in multimode waveguide crossings remains a challenge.

Purpose of the Study:

• To design and experimentally validate a polarization-insensitive multimode silicon waveguide crossing.
• To optimize the device for wide bandwidth, low insertion loss (IL), and low cross talk (CT).
• To achieve a compact device footprint.

Main Methods:

• Utilized particle swarm optimization (PSO) algorithm for device parameter tuning.
• Employed finite difference time domain (FDTD) method for electromagnetic simulation.
• Experimental characterization of the fabricated silicon waveguide crossing.

Main Results:

• The optimized device has a compact footprint of 11.92 μm × 11.92 μm.
• Achieved insertion loss below 0.67 dB and cross talk below -28.6 dB for TE0 and TE1 modes (1520-1600 nm).
• Demonstrated superior performance for TM0 mode (IL < 0.48 dB, CT < -36.3 dB) and TM1 mode (IL < 0.62 dB, CT < -28 dB).

Conclusions:

• The developed silicon waveguide crossing exhibits excellent polarization-insensitive performance.
• The device meets key metrics for insertion loss, cross talk, and bandwidth.
• This work contributes to the advancement of compact and efficient integrated photonic devices.