Acacia Communications, which was acquired by Cisco in 2021, is the first vendor out of the gate to ship a 1.2 Tbps optical module for optical transponders. The first units are going to an unnamed Tier-2 optical equipment vendor -- most likely Cisco, although ADTRAN/Adva and Ribbon Communications are other possible customers – for field trials at an unnamed Tier-1 service provider. An optical transponder is a system used in telecom central offices and data centers to connect switches and routers to metro/regional, long-haul and sub-sea networks.

This is a milestone. In the past 10-12 years, the state-of-the-art in optical networking has operated at hundreds of Gbps per wavelength channel. Presently, cutting edge operators are deploying 800 Gbps wavelengths, 400 Gbps is mainstream, and 100 Gbps is widely deployed. Speeds have been increasing at a rate of ~20 percent per year (see Figure). Now commercial systems have crossed the Terrabit mark.

Source: Winzer, et. al. "Fiber-optic transmission and networking: the previous 20 and the next 20 years
[Invited]," Opt. Express 26, 24190-24239 (2018)  

It’s tempting to get ‘into the weeds’ with how Acacia did it. Suffice to say, it was a combination of 5 nm process technology used to speed up its digital signal processor (DSP) and new and more powerful algorithms enabled by the faster DSP. Semiconductor industry advances to 3 nm, and soon 2 nm may enable yet higher speeds.

Crossing the Tbps threshold is a reminder of how far the industry has come in the past 40 years. In 1983, most traffic was still carried over various analog transmission systems. As a result, most digital communications used leased-line phone circuits and modems that operated at 9.6 kbps and less. Enterprise and government customers could sometimes get analog ‘group band’ circuits with modems that operated at 48 kbps. ‘T1’ digital transmission systems at 1.5 Mbps over twisted copper wires were in wide use in North American telco metro networks to carry phone calls; similar systems at 2 Mbps were in use in Europe. It wasn’t until the mid-80’s that the Bell System reluctantly began to offer T1 as a service to government and enterprise customers. The first fiber optic transmission systems were deployed in the late ‘70s at 45 Mbps, but the technology didn’t really become widespread until the early-to-mid ‘80s.

Think about it. 9600 bps. 48 kbps. 1.5 or 2 Mbps. 45 Mbps. 40 years later, 1.2 Tbps -- 8 orders of magnitude increase, and a 40 percent CAGR! Truly an impressive achievement of great minds in a variety of engineering and mathematical sub-disciplines.

All of that innovation was consequential. Over roughly the same period, traffic on the Internet (and its predecessor) grew at a ~57 percent CAGR. Of course, progress in this one dimension of optical communications was only one contributing factor to the growth of the Internet’s capacity. The point is that without the ability to deploy ever-faster wavelengths, Communications Service Providers (CSPs) and, more recently, Hyperscale Cloud Providers (HCPs) could not keep up with growing capacity demand. And without that capacity – among other things -- the Web would be stuck in the 1990s. Cloud and Video services could not exist. Broadband home Internet could not reach most of the households in industrialized countries. Work-from-home, connected health care, remote learning and personal videoconferencing -- all of which eased the impact of the COVID-19 pandemic -- would not be possible. In short, the world would be very different, for better or worse.

Kudos to Acacia for its big ‘first’. OFC, the optical communications industry’s biggest annual event, is coming up in March, and is the preferred venue for new product announcements. No doubt that more vendors will throw their hats in the ring over the coming weeks.