Silicon Photonics Based PAM4, DWDM Datacenter Interconnects

Although datacenters themselves are physical locations, limited in land area, the optical interconnects between them could span anywhere from tens of kilometers of terrestrial distances to thousands of kilometers of subsea routes. Figure 10.1 shows the worldwide footprint of the Microsoft datacenter network as of mid-2017 [1]. This supports 42 Azure regions (which themselves consist of hundreds of datacenters), 4,500 points of presence (or peering points), and over 130 edge locations [2]. All these facilities are interconnected over vast distances.