High capacity VCSEL-based links

▪ Commercial Cloud Servers and High Performance Computing (HPC) need higher data rate short distance links — 100% of Fiber Cables in Blue Gene Q Sequoia (20 PFlop system) < 23 m — 100% of Fiber Cables in largest Power 775 system < 28 m — Data Centers also have a lot of very short distance links ▪ Directly modulated VCSELs and Multimode fiber will satisfy Server, HPC and some datacenter needs for several generations to come. ▪ Multimode VCSEL-based technology is now and will likely be the cheapest and lowest power solution in this space for the foreseeable future. ▪ High Speed VCSEL technology keeps improving — Tremendous progress in single VCSEL speed in just past 4 years • 50 Gb/s reached in 2012 (NRZ) • 100 Gb/s reached in 2015 (DMT, Duobinary-PAM-4) • 150 Gb/s reached in 2016 (Poly-binary) — Equalization has extended the NRZ data rate > 71 Gb/s — Continued improvements in VCSEL bandwidth and RIN could realize 100 Gb/s NRZ — NRZ is preferred, PAM4+FEC adds undesired latency. — Continued improvements in DACs/ADCs for > 150 Gb/s HOM ▪ Optics needs to move to the First Level Package to realize full potential — If possible, sweep driver and receiver functions into the ASIC/Switch chip — SiGe first followed by CMOS later