The exponential growth of traffic demand and its explosion expected for the future mainly driven by smartphones and mobile internet is leading to a significant change in the design of next generation telecom hardware platforms and datacom equipment: the future platforms will have to be much more efficient in terms of energy consumption, footprint and cost, and will need to be architecturally simpler.
In data centers, cloud computing has received increasing attention due to its capability to dynamically provide services ranging from computing to networking and to storage, with resources distributed somewhere in the cloud and available on demand and transparent to end users. Fast growing services will require data centers to be significantly more powerful, energy efficient and compact. The challenges for equipment vendors will be to increase the bandwidth density and to decrease the consumption by two orders of magnitude by 2022.
Current optical interconnects are used only for inter-board communications, while for the intra-card level the electrical interconnects suffice. This is thanks to the required bandwidth of less than 100 Gb/s/cm2, the connections length of few centimeters and the data rate within 10 Gb/s. In the long run, however, also chip-to-chip communication inside a card will become optical due to increase in transmission rate up to 25 Gb/s and 50 Gb/s. During this transformation, the integrated technologies needs to evolve from moderate bandwidth-density parallel silicon photonics transceivers to high bandwidth-density 3D optical interposers, tightly integrated with electronic Application-Specific Integrated Circuits (ASIC) inside Optical Multi-Chip Modules (OMCM).
The global data center IP traffic will see a 23% cumulative annual growth rate, with a large majority of traffic (around 76%) exchanged within the data center itself, pushing even more communication load on data center servers and switches [1]. Regarding chip-to-chip interconnections, it is predicted a tenfold communication requirement increase by 2020 [2], which cannot be adequately satisfied by current standards, e.g. PCI-express. A recently published CIR report investigates the market trend for on-chip and chip-to-chip interconnects, showing great potentials for effective optical solutions, with chip-to-chip interconnection revenues reaching around $775 million by 2020, and on-chip interconnection revenues exceeding $210 million by 2025 [3].
[1] CISCO Systems, “Cisco Global Cloud Index: Forecast and Methodology, 2013–2018,” White Paper, 2014.
[2] Y. Arakawa, T. Nakamura, Y. Urino, and T. Fujita, “Silicon Photonics for Next Generation System Integration Platform,” IEEE Commun. Mag., vol. 51, no. 3, pp. 72-77, 2013
[3] CIR, “Markets for on-chip and chip-to-chip optical interconnects – 2015 to 2024,” Report # CIR-OI-MCC-0115, 2015.