Cross-polarization effects in sheared 2D grating couplers in a photonic BiCMOS technology

TL;DR

This paper explores how sheared 2D grating couplers in photonic BiCMOS technology exhibit cross-polarization effects that impact their splitting performance and efficiency, based on numerical and experimental analysis.

Contribution

It provides a detailed investigation of cross-polarization effects in sheared 2D grating couplers, highlighting their dependence on grating perturbation and implications for device performance.

Findings

Cross-polarization strongly depends on grating perturbation strength.

Cross-polarization limits both splitting performance and coupling efficiency.

Experimental and numerical results confirm the impact of shear angle on polarization effects.

Abstract

We investigate numerically and experimentally sheared 2D grating couplers in a photonic BiCMOS technology with a focus on their splitting behavior. Two realization forms of a waveguide-to-grating shear angle are considered. The cross-polarization used as a figure-of-merit is shown to be strongly dependent on the grating perturbation strength and is a crucial limitation not only for the grating splitting performance, but also for its coupling efficiency.