Evolution of System Embedded Optical Interconnect in Sub-Top-of-Rack Data Center Systems

Abstract

In this paper we review key technological milestones in system embedded optical interconnects in data centers that have been achieved between 2014 and 2020 on major European Union research and development projects. This includes the development of proprietary optically enabled data storage and switch systems and optically enabled data storage and compute subsystems. We report on four optically enabled data center system demonstrators: LightningValley, ThunderValley2, Pegasus and Aurora, which include advanced optical circuits based on polymer waveguides and fibers and proprietary electro-optical connectors. We also report on optically enabled subsystems including Ethernet-connected hard disk drives and microservers. Both are designed in the same pluggable carrier form factor and with embedded optical transceiver and connector interfaces, thus allowing, for the first time, both compute and storage nodes to be optically interchangeable and directly interconnectable over long distances. Finally, we present the Nexus platform, which allows different optically enabled data center test systems and subsystems to be interconnected and comparatively characterized within a data center test environment.

Photonic crystal enhanced Germanium photodetector on a CMOS compatible SOI platform

“…) 1 (c) ThunderValley2 -2nd generation optically enabled disaggregated SAS switch and storage platform (2014) 1 (d) Pegasus -Ethernet optically disaggregated and object oriented storage switch system 1 (e) SEPIANET -glass waveguide backplane interconnect 2 (f) Aurora -optical eco-system platform for polymer optical backplane and test daughtercards 3 (g) Aurora test daughtercard containing two mezzanine cards for PIC testing 3 (h) mezzanine card for PIC testing standardised by IEC (IEC 62150-6:2022) 3 (i) 1st generation silicon photonics PIC transceiver with vertical grating couplers developed on H2020 COSMICC project 3 (j) 2nd generation silicon photonics PIC transceiver with adiabatic couplers developed on H2020 COSMICC project. 3 Further author information: (Send correspondence to Aditya Jain) Aditya Jain.…”

Efficient and tolerant chip-to-chip optical coupling via silicon nitride grating couplers

“…Chip-to-chip optical interconnection has been considered an enabling technology to meet the requirements of data exchange applications with ultra-high speed and capacity. Efficient optical coupling between photonic chips is crucial for applications related to optical interconnection technology 1,2 . Commonly, inter-chip optical interconnection can be achieved by connecting the optical interfaces on distinct photonic chips using optical fibers which is so called the fiberto-chip solution 2 .…”

“…Efficient optical coupling between photonic chips is crucial for applications related to optical interconnection technology 1,2 . Commonly, inter-chip optical interconnection can be achieved by connecting the optical interfaces on distinct photonic chips using optical fibers which is so called the fiberto-chip solution 2 . However, further reducing the spacing between adjacent fibers in the fiber array (typically ~125 μm) has proven to be challenging.…”

Reconfigurable Generation of PAM-4 Signal Based on Fano Effect for Optical Interconnect Systems

“…The SOI waveguide can be fabricated by the CMOS existing technologies so it is compatible with CMOS processes [7]. Optical interconnects are the major commercial application of silicon photonics [8]. They are driven by the quickly increasing demand for high-speed optical links in data centers.…”