Dual-polarization multiplexing amorphous Si:H grating couplers for silicon photonic transmitters in the photonic BiCMOS backend of line

TL;DR

This paper demonstrates polarization combining 2D grating couplers on amorphous Si:H for silicon photonic transmitters, achieving efficient telecom C-band coupling in a BiCMOS platform with potential for future improvements.

Contribution

It introduces a novel integration of 2D grating couplers on amorphous Si:H within a photonic BiCMOS backend, enabling efficient polarization multiplexing for silicon photonic transmitters.

Findings

Achieved -5 dB coupling efficiency with +/-1.2 dB wafer variation.

Demonstrated operation in telecom C-band.

Outlined pathways for efficiency and stability improvements.

Abstract

We report on polarization combining 2D grating couplers (2D GCs) on amorphous Si:H, fabricated in the backend of line of a photonic BiCMOS platform. The 2D GCs can be used as an interface of a hybrid silicon photonic coherent transmitter, which can be implemented on bulk Si wafers. The fabricated 2D GCs operate in the telecom C-band and show an experimental coupling efficiency of -5 dB with a wafer variation of +/-1.2 dB. Possibilities for efficiency enhancement and improved performance stability in future design generations are outlined and extension towards O-band devices is investigated as well.