Infinera, in collaboration with Windstream, this week announced the successful trial of an 800 Gb/s single-wave transmission over 730 kilometers and a 700 Gb/s transmission over 1,460 kilometers. The trials mark the optical networking vendor's first public production trial of its sixth-generation optics.

The trial was conducted on a stretch of Windstream's network between San Diego and Phoenix using Infinera's Infinite Capacity Engine 6 (ICE6)-equipped Groove platform and standard G.652-compliant SMF-28 optical fiber.

"What we're trying to do with this trial is we really wanted to focus on a very real-world network application," explained Rob Shore, SVP of marketing at Infinera in an interview with SDxCentral. "We partner with network operators like Windstream because they're very forward looking, they have advanced networks, and they're constantly looking to embrace new technologies to make sure that they can leverage the benefits of those technologies in their network and bring those benefits to their customers."

But while Windstream's network may be more advanced than many long-haul networks, Shore emphasizes that Infinera went out of its way to avoid playing any games in order to boost the performance of its optics.

"We certainly didn't want to handpick a link, and we didn't want to pick one that had perfectly spaced amplifiers and stuff like that," Shore said.

According to Art Nichols, VP of architecture and technology at Windstream, the trial was conducted over a route that was "highly-representative" of Windstream's network as a whole. "It looks a lot like every other route in terms of fiber type, in terms of distance, the layout of the inline amplifiers," he added.

This is important because it enables Windstream to look forward and have confidence that the technology will perform similarly across the breadth of its network, Nichols said.

According to Shore, the trial used Windstram's existing equipment, which included the advanced reconfigurable optical add-drop multiplexers, and a standard add-drop structure. "All of the tricks that people use to create artificially good performance, we very intentionally avoided using any of them," he said.

To achieve the 1460 kilometer test, Infinera looped the signal back on itself effectively doubling the length of the original test in order to achieve a single-wave line-rate of 700 Gb/s.

According to Shore, Infinera's ability to achieve performance that far outstrips the capabilities of its rival's current-generation optics comes down to two factors.

"One is vertical integration. The fact that we build our own digital signal processors (DSP), we build our own front-end optical engines, and we do all of that in house," he said.

This enables Infinera to more tightly integrate the components and avoid optical penalties. "A lot of people who don't build their own optics and only build their own DSP, they actually incur a lot of optical penalties," Shore said.

The other factor enabling this kind of performance is the use Nyquist subcarriers. Rather than using a single carrier for the transmission of data, Infinera divides the carrier signal into smaller subcarriers.

"Having Nyquist subcarriers gives us two really key benefits," said Shore. "No. 1, the subcarriers themselves improve transmission performance."

This is because lower baud rates incur less chromatic dispersion resulting in a much cleaner signal over distance.

According to Shore, Nyquist subcarriers, also enable other corrective technologies to be applied to the individual subcarrier, something that improves the overall performance of the network.

The trial flies in the face of claims made by Nokia in a recent blog post calling out its competitors for what it considered misleading 800 Gb/s fiber optic field trials.

“Carriers should expect 100-220 kilometer optical reach in most wave division multiplexing applications,” wrote Nokia’s Randy Eisenach, discussing competitors’ 800 Gb/s offerings. “For carriers, it’s important to understand actual realistic network performance that can be expected when using high-capacity wavelengths, as opposed to demo experiments.”

In the post, Eisenach claimed 800 Gb/s speeds were next to impossible under real-world conditions using the current generation of DSPs.

Nokia argued that vendors were misleading carriers by using low-latency fiber, eliminating spare margin, and removing guard band channels, to eke out higher performance.

According to Shore, none of these tactics were used in its most recent trial with Windstream and the margins were well within the network operators' standards.

Meanwhile Ciena, in a previous statement said it never misrepresented the capabilities of its optics, and called Nokia’s insinuations patently false. The company claims its WaveLogic 5 Extreme optics, are capable of 800 Gb/s line rates at distances of 80 to 240 kilometers.