Mode-evolution-based ultra-broadband polarization beam splitter using adiabatically tapered extreme skin-depth...

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• Polarization beam splitters (PBS) are essential components in photonic integrated circuits for controlling light polarization.
• Existing PBS technologies often face limitations in bandwidth, crosstalk suppression, and fabrication tolerance.
• Extreme skin-depth (eskid) waveguides offer unique properties for manipulating light modes due to their anisotropic metamaterial claddings.

Purpose of the Study:

• To design and demonstrate an ultra-broadband silicon photonic polarization beam splitter (PBS).
• To leverage adiabatically tapered eskid waveguides for efficient polarization splitting with low crosstalk.
• To achieve a PBS tolerant to fabrication imperfections for practical photonic circuit integration.

Main Methods:

• Utilized adiabatically tapered extreme skin-depth (eskid) waveguides with highly anisotropic metamaterial claddings.
• Designed the tapered waveguide cross-section numerically to optimize mode evolution and coupling.
• Suppressed transverse-electric (TE) mode crosstalk using metamaterial claddings and cross-coupled transverse-magnetic (TM) mode via large birefringence.

Main Results:

• Achieved a numerically designed bandwidth of 1400-1650 nm with extinction ratios exceeding 20 dB.
• Experimentally demonstrated a tapered-eskid PBS with a broad operational bandwidth from 1490-1640 nm.
• The device exhibited tolerance to fabrication imperfections due to its mode evolution design.

Conclusions:

• The adiabatically tapered eskid PBS offers an ultra-broadband solution for polarization control in silicon photonics.
• The device's design ensures efficient TM mode translation while maintaining TE mode in the through port.
• This technology is crucial for advancing polarization management in complex photonic circuits.