New broadband applications are causing the datacenters to proliferate, raising the bar for higher interconnection speeds.
So far, optical board-to-board and rack-to-rack interconnects relied primarily on low-cost commodity optical
components assembled in a single package. Although this concept proved successful in the first generations of opticalinterconnect
modules, scalability is a daunting issue as signaling rates extend beyond 25 Gb/s. In this paper we present
our work towards the development of two technology platforms for migration beyond Infiniband enhanced data rate
(EDR), introducing new concepts in board-to-board and rack-to-rack interconnects.
The first platform is developed in the framework of MIRAGE European project and relies on proven VCSEL
technology, exploiting the inherent cost, yield, reliability and power consumption advantages of VCSELs. Wavelength
multiplexing, PAM-4 modulation and multi-core fiber (MCF) multiplexing are introduced by combining VCSELs with
integrated Si and glass photonics as well as BiCMOS electronics. An in-plane MCF-to-SOI interface is demonstrated,
allowing coupling from the MCF cores to 340x400 nm Si waveguides. Development of a low-power VCSEL driver with
integrated feed-forward equalizer is reported, allowing PAM-4 modulation of a bandwidth-limited VCSEL beyond 25
The second platform, developed within the frames of the European project PHOXTROT, considers the use of
modulation formats of increased complexity in the context of optical interconnects. Powered by the evolution of DSP
technology and towards an integration path between inter and intra datacenter traffic, this platform investigates optical
interconnection system concepts capable to support 16QAM 40GBd data traffic, exploiting the advancements of silicon
and polymer technologies.