Polarization-independent vertical coupler for photonics integration.

Area of Science:

• Photonics
• Integrated Optics
• Optical Engineering

Background:

• Minimizing insertion loss is crucial for photonic integrated circuits.
• Mode-size transformers are essential components for interfacing different photonic structures.
• Existing designs often suffer from polarization dependence, limiting their application.

Purpose of the Study:

• To present a systematic design approach for compact polarization-independent mode-size transformers.
• To demonstrate high transfer efficiencies for these devices.
• To establish a versatile building block for advanced photonic integrated circuits.

Main Methods:

• Utilizing tapered resonant vertical couplers.
• Identifying critical taper widths for polarization independence.
• Achieving resonant coupling at equal TE and TM effective indices.

Main Results:

• Demonstrated the first systematic design for polarization-independent mode-size transformers.
• Achieved transfer efficiencies greater than 90%.
• Confirmed polarization-independent operation at a critical taper width.

Conclusions:

• The developed mode-size transformers are highly efficient and polarization-independent.
• These devices offer a significant advancement for reducing insertion loss in photonic integrated circuits.
• The polarization-independent vertical coupler serves as a valuable building block for future photonic applications.