OFC 2016: PAM4 is the new binary
The best way to see what's coming next at DesignCon is to attend OFC, the gathering of the optical communications community. At OFC 2014, I attended a panel session where engineers discussed PAM4, NRZ, and ENRZ modulation formats. PAM4 then took the spotlight at DesignCon 2015's opening night panel. For 2016, PAM4 practically took over DesignCon with two panels and nine papers.
Whenever the optical folks come up with a way to increase data rates over fiber, that's when the real work begins. Why? Because engineers on the electrical side then have to achieve those data rates over copper and inside silicon.
PAM4 made deeper cuts at OFC 2016. During a panel discussion on the state of pluggable optical modules on March 22, Vipul Bhatt, director of engineering at Inphi said "PAM4 is the new binary."
The two videos below highlight some of the PAM4 demonstrations seen on March 22, the opening day of the OFC 2016 exhibition.
Xilinx demonstrated a Gbps 56PAM4 signal running from its FPGAs. The company also demonstrated 56 Gbps NRZ signals.
Tektronix demonstrated a single-lane, 100 Gpbs optical signal to show that it's possible to do. Although 400 Gbps Ethernet will likely be based on 8x50 Gbps lanes, this setup shows that 4x100 Gpbs just might be possible. Furthermore, just as 100 Gbps is currently build with 4x25 Gbps lanes, a 25 Gbps standard is in the works. We could someday see a standard for a single-lane 100 Gbps standard, for it could be done with a single transmitter-receiver pair.