Compact and broadband silicon polarization splitter-rotator using adiabaticity engineering

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Polarization-sensitive optical components are crucial in integrated photonics.
• Existing polarization splitter-rotators (PSRs) often suffer from large footprints or limited bandwidth.

Purpose of the Study:

• To propose and demonstrate a novel, short, and broadband silicon mode-conversion polarization splitter-rotator (PSR).
• To leverage adiabaticity engineering (AE) for enhanced device performance and reduced length.

Main Methods:

• Device design utilizing a mode-conversion taper and an adiabatic coupler-based mode sorter.
• Optimization through adiabaticity engineering (AE) to control adiabaticity parameter distribution.
• Fabrication on standard silicon photonics platforms with a single patterning step.

Main Results:

• Achieved a compact PSR with a total length of 85 µm.
• Demonstrated low polarization crosstalk (< -20 dB for TE, < -15 dB for TM) across the O-band.
• Exhibited low polarization crosstalk (< -15 dB) over an 81 nm bandwidth in the O-band.
• Cross-wafer measurements confirmed good fabrication tolerance.

Conclusions:

• The proposed AE-optimized silicon PSR offers a compact and broadband solution for polarization management.
• The design's compatibility with standard silicon photonics processes and single patterning step facilitate integration.
• The device demonstrates excellent performance metrics, including low crosstalk and good fabrication tolerance.