Inverse design and implementation of a wavelength demultiplexing grating coupler

TL;DR

This paper demonstrates an inverse design method for nanophotonic devices, specifically creating a novel wavelength demultiplexing grating coupler that separates different wavelength bands efficiently, surpassing traditional design approaches.

Contribution

The paper introduces a new inverse design technique that specifies target fields instead of dielectric profiles, enabling the creation of innovative nanophotonic components like the wavelength demultiplexing grating.

Findings

Designed a grating that separates 1300nm and 1550nm light into different waveguides.

The inverse design method simplifies device creation and can be extended to various compact photonic devices.

Achieved device performance surpassing conventional design methods.

Abstract

Nanophotonics has emerged as a powerful tool for manipulating light on chips. Almost all of today's devices, however, have been designed using slow and ineffective brute-force search methods, leading in many cases to limited device performance. In this article, we provide a complete demonstration of our recently proposed inverse design technique, wherein the user specifies design constraints in the form of target fields rather than a dielectric constant profile, and in particular we use this method to demonstrate a new demultiplexing grating. The novel grating, which has not been developed using conventional techniques, accepts a vertical-incident Gaussian beam from a free-space and separates O-band $(1300\mathrm{nm})$ and C-band $(1550\mathrm{nm})$ light into separate waveguides. This inverse design concept is simple and extendable to a broad class of highly compact devices including frequency splitters, mode converters, and spatial mode multiplexers.