The Role of PICs in the Data Communications Roadmap
As bandwidth consumption continues its meteoric rise, the complexity of optical links and the transceivers within them continue to increase in complexity. Yet at the same time, data center operators are demanding more efficiency. Current discrete optical subassemblies can no longer meet future transceiver requirements. The time has come for PICs to deliver on their promise and save the future of optical transceivers. In this article, the role of PICs in future optical transceivers is examined.
By Jim Theodoras, HG Genuine
A quick peruse of the leading optical industry news sources reveals that Photonic Integrated Circuits (PICs) continue to be an area of substantial hype and investment. Given the global impact of silicon integrated circuits, it is no surprise that the optical industry has spent decades trying to replicate the success. PIC categories, types, and technologies are as widely varied and numerous as the color swatches at a paint store. A more recent area of focus is the use of PICs in optical communications, as they hold the promise of breaking the bandwidth logjam that is rapidly building up with traditional techniques.
Bandwidth consumption is outpacing the pace at which the optical communication industry can respond. Three ways of increasing an optical channel’s throughput is to simply go faster (increase bits per second), go wider (increase the number channels), or get smarter (more complicated modulations than just on/off). The industry has done an admirable job of increasing laser modulation speeds over the decades, but more recently speeds cannot keep up with needs. The industry recently made the difficult jump to PAM4 modulation, which doubled throughputs, helping with the inability of speed to scale fast enough. But even faster lasers and higher order modulations have not been enough, and so the number of channels in each link continues to climb. Looking at standard Ethernet, the physical link definitions have grown from one to four to eight lanes, with 16 lanes on the horizon.