Photonic Wire Bonds for Terabit/s Chip-to-Chip Interconnects

TL;DR

This paper introduces photonic wire bonding, a novel technique for creating 3D freeform optical interconnects between chips, enabling high-speed data transmission with low loss and supporting the development of flexible multi-chip photonic systems.

Contribution

It presents the first fabrication and demonstration of 3D freeform photonic wire bonds for chip-to-chip optical interconnects at Terabit/s data rates.

Findings

Achieved broadband coupling with only 1.6 dB loss.

Demonstrated multi-Terabit/s data transmission.

Enabled flexible multi-chip photonic integration.

Abstract

Photonic integration has witnessed tremendous progress over the last years, and chip-scale transceiver systems with Terabit/s data rates have come into reach. However, as on-chip integration density increases, efficient off-chip interfaces are becoming more and more crucial. A technological breakthrough is considered indispensable to cope with the challenges arising from large-scale photonic integration, and this particularly applies to short-distance optical interconnects. In this letter we introduce the concept of photonic wire bonding, where transparent waveguide wire bonds are used to bridge the gap between nanophotonic circuits located on different chips. We demonstrate for the first time the fabrication of three-dimensional freeform photonic wire bonds (PWB), and we confirm their viability in a multi-Terabit/s data transmission experiment. First-generation prototypes allow for efficient broadband coupling with overall losses of only 1.6 dB. Photonic wire bonding will enable flexible optical multi-chip assemblies, thereby challenging the current paradigm of highly-complex monolithic integration.