Fabrication tolerant multi-layer integrated photonic topology optimization.

Area of Science:

• Optics and photonics
• Materials science
• Computational engineering

Background:

• Multi-layer device fabrication faces challenges from inter-layer alignment and conformal layering uncertainties.
• Topology optimization (TO) is crucial for designing complex devices but requires adaptation for multi-layer structures.
• Existing TO methods struggle with the specific constraints of multi-layer fabrication processes.

Purpose of the Study:

• To introduce a novel layer-restricted topology optimization (TO) technique for multi-layer device design.
• To develop a robust TO formulation that accounts for inter-layer misalignment.
• To demonstrate the efficacy of these methods in practical photonic device applications.

Main Methods:

• Layer-restricted topology optimization (TO) was developed to control conformal layering.
• Several approaches compatible with density-based TO projection and geometric constraints were explored.
• A robust TO formulation was created to enhance resilience against inter-layer misalignment.
• The methods were applied to design 2D grating couplers and 3D polarization rotators.

Main Results:

• The layer-restricted TO successfully mitigates unwanted conformal layering in multi-layer structures.
• The robust TO formulation enables the design of devices tolerant to inter-layer misalignment.
• Demonstrated improvements in 2D grating couplers and 3D polarization rotators using the novel methods.
• The technique is compatible with multi-etch material platforms.

Conclusions:

• Layer-restricted TO is a novel and effective technique for optimizing multi-layer device fabrication.
• Robust TO formulations are essential for designing devices resilient to fabrication uncertainties.
• The presented methods offer a pathway to more reliable and high-performance multi-layer photonic devices.