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In the Zone

How silicon photonics connects servers at the speed of light

Peter Krass's picture

by Peter Krass on 07/13/2021
Blog Category: cloud-and-data-centers

For data-center managers, data bottlenecks are a big and fast-growing problem. Among large organizations, data traffic can double every 2 years. That kind of growth can put real strain on a data center’s networking gear.

One powerful way to ease these bottlenecks: replace older copper-based transceivers with faster optical transceivers.

These optical transceivers and their cabling offer several advantages over their copper-based predecessors. They’re faster. Far less bulky. Highly reliable. Qualified to extreme ambient temperatures. And able to send data over much longer distances — 10 kilometers to copper’s 4 meters, and at 25 gigabits per second (Gbps) per lane.

Intel’s bright light

Intel got into the silicon photonics optical transceiver business early, back in 2016. Actually, the company had been selling its 1/10/25 Gigabit Ethernet (GbE) optics in the channel for much longer than that. But as speeds increased beyond 25 GbE, Intel decided it made sense to bring integrated optics in-house.

With networking speeds increasing from 100 Mbps to 400 Gbps (and soon, even faster), it become critical for Intel to align the optics and the lenses within its transceivers. That meant higher assembly complexity, which isn’t great if you’re looking for scalability, high yields and low cost. Clearly, Intel needed another method for aligning the lenses accurately.

Enter Silicon Photonics. It puts the lasers, modulators, detectors and all other optical elements within silicon, and without the need to align them optically.

Early optical transceivers had just 1 laser on a chip. Today they have 4 or even 8. What’s more, these lasers can now be run at different wavelengths for 4x or 8x faster modulation per fiber.

Demand for silicon photonics is big. Intel says it shipped some 2 million optical transceivers last year. The company also shipped more than 5 million 100 Gbps transceivers to date.

The following chart, from Crehan Research, shows that 100 GbE ports are forecast to outship both 10 and 25 GbE ports. You can see this by comparing the rising green line (100 GbE) with the falling purple (10) and red (25).

Crehan Research chart

To date, most of these shipments have gone to big hyperscale data centers, such as those run by AWS, Google and other providers of cloud. As you can imagine, these users have an insatiable appetite for data speeds. Indeed, Intel is now sampling 8-laser optical transceivers rated at 800 Gbps.

Light years ahead

That’s extreme. For many data centers, 100 Gbps is now the standard currency. And for these customers, Intel offers its Intel Silicon Photonics 100G CWDM4 QSFP28 Optical Transceiver, pictured below.

Intel Silicon Photonics optical transceiver

Typical orders for these transceivers number in the hundreds or thousands. That may seem high, but note that each Ethernet switch gets 32 optical transceivers. For example, if your customer had just 10 switches, they’d need 32 x 10 = 320 transceivers.

Assuming 100Gbps transceivers, these would be 3.2-terabit Ethernet switches. With this number, you might be able to support 8 racks of servers. Each rack would have 1 top-of-rack switch, and each would use 2 switches for aggregation and interfacing with your transport equipment. Plus, you’d need 1 additional transceiver for each server, which in this example would total about 200 units.

Improve your data-center networking skills

If you’re still with me, then you’ll be interested in a new training course being offered by Intel Partner University. The course is Optical Networking at Scale with Intel Silicon Photonics.

In this course, you’ll learn about the advancements Intel has made in Silicon Photonics over the last four years since launching 100 Gbps transceivers. You’ll also learn how, by manufacturing optics at scale, Intel has deployed more than 5 million transceivers to date for hyperscale data centers.

This course also reviews industry trends in optical networking inside data centers, as well as the key building blocks of pluggable optical transceivers. The presentation also looks at the benefits of co-packaged optics, which is expected to begin deployment in the next 2 to 3 years. Then it all wraps up with a brief forecast of future applications for high-volume Silicon Photonics beyond the data center.

Take the “Optical Networking at Scale with Intel Silicon Photonics” training course today

Get connected:

> Explore Intel Silicon Photonics

> Intel Silicon Photonics 100G CWDM4 QSFP28 Optical Transceiver (product brief)

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