New silicon photonics integration platform enabled by novel micron-scale bends

TL;DR

This paper introduces a new silicon photonics platform utilizing micron-scale waveguides with novel Euler spiral bends that achieve ultra-compact radii and low losses, enabling denser integration of photonic circuits.

Contribution

The authors demonstrate a novel approach to achieve sub-10 micron bending radii in micron-scale silicon waveguides using Euler spiral bends, improving integration density.

Findings

Bending radii below 10 μm with low loss (<0.02 dB/90°) are achievable.

Euler spiral bends enable high-density photonic integration.

The platform maintains single-mode operation with large core dimensions.

Abstract

Even though submicron silicon waveguides have been proposed for dense integration of photonic devices, to date the lightwave circuits on the market mainly rely on waveguides with micron-scale core dimensions. These larger waveguides feature easier fabrication, higher reliability and better interfacing to optical fibres. Single-mode operation with large core dimensions is obtained with low lateral refractive index contrast. Hence, the main limitation in increasing the level of integration and in reducing the cost of micron-scale waveguide circuits is their mm- to cm-scale minimum bending radius. Fortunately, single-mode rib waveguides with a micron-scale silicon core can be locally transformed into multi-mode strip waveguides that have very high lateral index contrast. Here we show how Euler spiral bends realized with these waveguides can have bending radii below 10 {\mu}m and losses below 0.02 dB/90{\deg} for the fundamental mode, paving way for a novel densely integrated platform based on micron-scale waveguides.