Silicon Photonics for Datacenter Applications

With the growing demand for centralized data storage and processing large data centers have become an integral part of the strategy of large content and service providers such as Google, Amazon, Microsoft etc. Currently mega-data-centers in the size of large storehouses are built and evolve more and more to crosspoints of the global IT infrastructure. In mega-data-centers optical communications plays a crucial role because it allows to realize networks with longer range, higher data rate, lower latency, and lower power dissipation. In data centers very large numbers of optical transceivers will be utilized which however will have to fulfill stringent requirements in terms of cost, power dissipation, and size.

Here the advantages of silicon photonics technology become evident which allows to integrate optical and electronic functions monolithically and in a mass fabrication process thus reducing cost, power dissipation, and size. Silicon photonics technology is becoming a more and more mature technology and starts to enter the communication market. This trend is picked up by the BMBF-project SPEED (Silicon Photonics Enabling Exascale Data Networks) in order to pioneer a German platform for application-specific, electronic-photonic ICs and to develop on this basis innovative transceiver technology for data center applications.

Electronic-Photonic ICs for Data Transmission with 400 Gb/s

In the frame of the SPEED project the working group System and Circuit Technology of the Heinz Nixdorf Institute works together with 11 industrial and academic partners on next-generation fiber-optic transceivers for 400 Gb/s data transmission. Two different transceiver types will be realized as silicon ICs which address both intra-data-center and inter-data-center communication. The intra-data-center transceiver operates with direct detection and will exhibit a range of 2 km over single-mode fiber. The transceiver is operating with 4 wavelengths using coarse wavelength division multiplexing (CWDM) where each wavelength transmits 100 Gb/s by means of 4-level pulse amplitude modulation. The inter-data-center transceiver will use wavelength-tuning and coherent detection and targets a range of 80 km. It is operated in dense wavelength division multiplexing (DWDM) in order to allow transmission of up to 96 optical channels in a single fiber achieving a fiber capacity of 25 Tb/s.