What Are the Trends and Timing Needs for Next-Gen Optical Communications?

EpsonOctober 16, 2020

The IDC data growth forecast estimates that more than 58 zettabytes of data will be created, captured, copied, and consumed in 2020. The same forecast predicts the amount of data created in the next three years will surpass all the data created in the past 30. Few will find it surprising that data consumption is growing exponentially, particularly data center operators and service providers. They must prepare to meet not only today’s already demanding needs, but also position themselves and their facilities to match this anticipated growth.

The Need for Cleaner Signals and the Challenges for Meeting that Goal

Optical communications are the primary tool for meeting data growth demands. These communications pathways meet those needs by enabling data transmissions over greater distances with higher data rates and cleaner signals. As you move more data at faster speeds, the accuracy and reliability of those transmissions matters more than ever. If data is corrupted during transmission, that requires resending the data, adding to an already heavy traffic load. Clean timing signals (with minimal phase noise/phase jitter) helps ensure that fidelity and prevent the need for retransmission.

While aiming for fidelity and optimal user experience, data center operators must balance competing needs: provide as much bandwidth as they can, with as low a cost and as low power consumption as possible. Achieving this balance provides the greatest challenge to meeting user expectations. As integrated circuit (IC) and module vendors can attest, tech advances have helped achieve that balance by allowing data centers to consume and share data much faster. Ever new generation of technology aims to keep power consumption the same, while doubling or even quadrupling the speed of data being sent. Upgrading data centers is capital intensive, but newer generations of technology allow improvements in speed while also lowering costs and keeping power consumption the same or even lower.

The Data Transfer Technology Used by Data Centers

Two primary technologies govern optical communications: Coherent and pulse-amplitude modulation 4-level (PAM4). Coherent is primarily used over long distances, such as between geographically separate data centers (for example, between cities). PAM4 is primarily used over shorter distances, such as within data centers or between data centers on the same campus. These two technologies currently do not compete with each other because they have different capabilities and advantages that apply to different uses. Coherent works across long distances but is not necessarily cost efficient and demands high power consumption. PAM4 costs less and consumes less power but cannot extend across long distances.

While these two technologies don’t compete now, changes being made to improve the drawbacks of each type offer hints for what’s to come. Coherent and PAM4 transmissions are strengthening their previous weaknesses to the point where they might eventually become interchangeable. If that happens, it would be possible for data centers to rely on one technology across all uses. To need only one technology would allow data centers to be more nimble, adjusting to changing user needs with greater speed. That’s necessary because data centers must be efficient, faster, and more cost effective to manage the data growth explosion as well as the proliferation of cloud. In addition to data transfer technology improvements, this agility is also being made possible through better and smaller optical module products. The new next-gen optical modules provide greater bandwidth (more data capacity) in the same footprint, consume less or comparable power, and cost less than the previous generations. Those features fit hand in glove with the needs of data centers to balance their competing needs.

Service providers and data center operators may ultimately need to choose one technology over the other. The way timing devices enable those two options will also play a role in whether one technology will lead over another. Anyone looking to future proof their networks understands that timing signals, especially considered from a phase jitter standpoint, will be critical to enable mass adoption. The size of optical modules will also play a role in the widespread embrace of a leading technology. Given the common footprint of a server rack, smaller optical modules make advanced technologies more appealing. It’s a win for data centers if more modules can be added to the same rack footprint. The interplay of data transfer capabilities and optical modules will factor significantly into which technology—Coherent or PAM4—prevails.

Epson’s Role in Advancing Next-Gen Technologies

Epson is a member of the Optical Internetworking Forum (OIF) standards committee. Epson’s role as a timing leader is to advise on the most efficient way to meet the timing challenges for these new optical technologies. Recently, OIF created an implementation agreement for 400ZR, a Coherent optical interface that is better suited for shorter distances. This implementation makes Coherent more adaptable to cover a wider range of geographies, both short and long distances, required by data center operators. The Epson H Series presents a huge step toward achieving that standard. It  delivers the first oscillator to combine high frequency, low noise, low power consumption, and high frequency stability needed in 400ZR optical modules, which again helps data center operators and service providers balance their competing needs in meeting user demand and data growth expectations. Epson’s contributions to 400ZR may help create a standard that forever changes the landscape of data center and cloud computing.

To learn more about Epson is making an impact on next-gen optical communications, visit the Microdevices home page today.