Fully-automated optimization of grating couplers

TL;DR

This paper introduces a fully-automated, gradient-based algorithm for designing versatile 1D grating couplers with multiple functionalities, achieving high efficiency and simplified fabrication without human intervention.

Contribution

It presents a novel automated design method for 1D grating couplers capable of multiple functionalities, reducing design complexity and fabrication steps.

Findings

Designed a fiber-to-chip grating with under 0.2 dB loss

Achieved polarization-insensitive and wavelength-demultiplexing functionalities

Developed a method requiring no human input or back-reflector

Abstract

We present a gradient-based algorithm to design general 1D grating couplers without any human input from start to finish, including a choice of initial condition. We show that we can reliably design efficient couplers to have multiple functionalities in different geometries, including conventional couplers for single-polarization and single-wavelength operation, polarization-insensitive couplers, and wavelength-demultiplexing couplers. In particular, we design a fiber-to-chip blazed grating with under 0.2 dB insertion loss that requires a single etch to fabricate and no back-reflector.