Adjoint optimization of polarization-splitting grating couplers

TL;DR

This paper presents a novel adjoint optimization approach to design silicon-on-insulator polarization-splitting grating couplers with record low simulated peak loss, enabling complex geometries and transferable insights.

Contribution

The paper introduces an adjoint-based shape optimization method for PSGCs, achieving the lowest simulated loss without a bottom reflector and extracting transferable physics-based design knowledge.

Findings

Achieved 1.2 dB peak loss in simulations, the best reported for PSGCs without a bottom reflector.

Demonstrated the effectiveness of adjoint optimization in exploring complex geometries.

Extracted physics-based knowledge that can be transferred to other platforms.

Abstract

We have designed a polarization-splitting grating coupler (PSGC) in silicon-oninsulator (SOI) that has 1.2 dB peak loss in numerical simulations, which is the best simulated performance of PSGCs without a bottom reflector to the best of our knowledge. Adjoint method-based shape optimization enables us to explore complex geometries that are intractable with conventional design approaches. Physics-based process-independent knowledge of PSGCs is extracted from the adjoint optimization and can be transferred to other platforms with a minimum of effort.