Loss-induced high-density multi-mode integrated waveguides array

TL;DR

This paper introduces a universal, high-density multi-mode waveguide array using high-loss metal strips to suppress coupling, achieving ultra-close spacing and broad bandwidth with high fabrication tolerance.

Contribution

The authors propose a novel high-loss metal strip approach for dense multi-mode waveguides, offering a universal, fabrication-tolerant solution applicable across platforms and wavebands.

Findings

Achieved 10-channel multi-mode waveguides with 6.6 um total spacing.

Waveguides with 400 nm close spacing demonstrate high density.

Scheme exhibits high fabrication tolerance and broad bandwidth.

Abstract

The integration density of photonic integrated circuits has been limited by light coupling between waveguides. Traditional approaches to layout the waveguide with high density are based on refractive index engineering to suppress the light coupling between waveguides. However, these methods mostly require sophisticated and sensitive structure design, thus lack universality. Herein, we propose high-density multi-mode-multi-core integrated photonic waveguides by inserting high-loss metal strips between waveguides. We have achieved a 10-spatial-channel multi-mode-multi-core waveguide with total occupying spacing of 6.6 um. The multi-mode waveguides have a close spacing of 400 nm. The proposed scheme has high fabrication tolerance, ultra-large bandwidth and good compatibility to the complementary metal-oxide-semiconductor technology. It can be applied to any integration platform, any working waveband and any operating mode, providing a universal solution for high-density photonic circuits.