High-extinction-ratio directional-coupler-type polarization beam splitter with a bridged silicon wire waveguide

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Semiconductor Devices

Background:

• Polarization beam splitters (PBS) are crucial components in integrated photonic circuits.
• Existing PBS designs often face challenges with size, performance, or fabrication complexity.
• High polarization extinction ratios (PERs) and low insertion loss are key metrics for efficient optical signal processing.

Purpose of the Study:

• To design and fabricate a compact and efficient silicon-based polarization beam splitter (PBS).
• To achieve high polarization extinction ratios (PERs) for both transverse electric (TE) and transverse magnetic (TM) modes.
• To minimize insertion loss for practical applications in integrated photonic systems.

Main Methods:

• Numerical simulation of a three-waveguide directional coupler to optimize device parameters for a silicon PBS.
• Experimental fabrication of the optimized silicon PBS design.
• Measurement of PER and insertion loss for the fabricated devices.

Main Results:

• The fabricated silicon PBS exhibits high PERs: 40.74 dB for TE modes and 39.01 dB for TM modes.
• The average insertion loss is as low as 0.35 dB.
• The device features a compact geometry with a coupler length of approximately 29.4 μm.

Conclusions:

• A simple, compact, and high-performance silicon polarization beam splitter (PBS) has been successfully demonstrated.
• The achieved PER and low insertion loss meet stringent requirements for advanced integrated photonic applications.
• The three-waveguide directional coupler approach offers a promising route for on-chip polarization control devices.