The Future of Fiber Optic Communications Observations from OFC 16
Anyone reading Fiber and Integrated Optics has a story about the history of optical communications. Mine started the 1970s. At the time, I worked with Honeywell's Systems and Research Center. In a brilliant move, we teamed with Bob Biard of Spectronics to make a 10 Mb/s fiber optic link. He was an inventor of the LED and handled the optoelectronics side of our project. He brought some interesting innovations to the link design. The one I remember was the key for good coupling of light from the 3.6 refractive index GaAs mesa structure to a multi mode fiber. Bob managed it with some index 2.0 glass spheres that he picked up from the highway crew; they used them to make road markings retroreflective. Soon, Honeywell bought Bob's company. Ten years ago Honeywell sold his verticalcavity surface emitting laser (VCSEL) group to Finisar one of the stars of the Optical Fiber Communications (OFC) Conference last month in Anaheim. The OFC Conference had 1,160 peer reviewed papers, 580 exhibitors, and 13,000 attendees; there were many activities. The future of fiber optic communications at OFC can be understood from the photo in Figure 1. This is the data center summit, the big story of OFC 16. Most of the papers at OFC were typical academic presentations in rooms that seated a few dozen. Not this one. The focus of the energy this year was fiber communications for data centers. The excitement of fiber optic data center systems began a day before in Prof. Clint Schow's short course "Photonic technologies in the datacenter," OFC 2016 Short Course 431) He chronicled how we got here with obvious Internet growth (http:/www.intel.com/ content/www/us/en/communications/internet minute infographic.html) and the transition from telecom fiber applications (high reliability) to internal data center fibers (low cost) Current data traffic is 73% within the data center (http:/www.cisco.com/c/dam/ assets/sol/sp/gci/global cloud index infographic.html) Advantages for links within the data center are <100 m distances, short hardware lifetimes, and lots of redundancy. Costs for links are decreasing toward $1/Gb/s. Schow described the tradeoffs in optical transmitters and receivers. Current products, such as Quad Small Form Factor Pluggable Transceivers QSFP28 products, can support a single 100 Gb/s link or four 25 Gb/s links. More complex systems can use multi level signaling, for example PAM 4, in a paper from Finisar (Matsui, Y. Pham, T. Sudo, T. Carey, G. Young, B. and Roxlo, C. "112 Gb/sWDM