Inverse design and demonstration of a compact and broadband on-chip wavelength demultiplexer

TL;DR

This paper introduces an inverse design approach for creating compact, broadband on-chip wavelength demultiplexers, demonstrating devices with superior performance and minimal size compared to traditional designs.

Contribution

The study presents a novel inverse design method enabling the creation of highly efficient, small-footprint wavelength demultiplexers with enhanced functionality and robustness.

Findings

Devices exhibit low insertion loss (2-4 dB)

High contrast (12-17 dB) achieved

Device footprint is 2.8 x 2.8 μm, smallest to date

Abstract

Integrated photonic devices are poised to play a key role in a wide variety of applications, ranging from optical interconnects and sensors to quantum computing. However, only a small library of semi-analytically designed devices are currently known. In this paper, we demonstrate the use of an inverse design method that explores the full design space of fabricable devices and allows us to design devices with previously unattainable functionality, higher performance and robustness, and smaller footprints compared to conventional devices. We designed a silicon wavelength demultiplexer that splits $1300~\mathrm{nm}$ and $1550~\mathrm{nm}$ light from an input waveguide into two output waveguides, and fabricated and characterized several devices. The devices display low insertion loss $\left(2 - 4~\mathrm{dB}\right)$, high contrast $\left(12 - 17~\mathrm{dB}\right)$, and wide bandwidths $\left(\sim 100~\mathrm{nm} \right)$. The device footprint is $2.8 \times 2.8 ~\mathrm{\mu m}$, making this the smallest dielectric wavelength splitter to date.