PCI-SIG Is Developing An Optical Interconnect To Supercharge PCIe Performance

optical connection PCIe standard hero
The technology behind PCI Express interface looks set for a significant technological revamp. Signs of big changes afoot come via a press release from the PCI Special Interest Group, or PCI-SIG, which has just announced that it is going to explore delivering PCIe over optical connections.

The blistering transfer speeds delivered by the latest iteration of the PCIe standard, PCIe Gen5, are unfortunately tied to blistering heat. The interface consumes a lot of power and signal integrity concerns will only become more relevant with future revisions. Moving to an optical interface could help with these concerns but won't eliminate thermal problems entirely. Previous generation PCIe storage devices, for example, could run bare or with a simple heatsink, but many storage device manufacturers in 2023 are bundling or recommending active cooling for their PCIe Gen5 SSDs. This is due to the SSD's controller having to process all that data, and the trend will accelerate.

Hot Hardware readers are probably quite familiar with optical technologies coming to computing. Light-based communications last featured in our headlines back in May, when NASA used a so-called TeraByte InfraRed Delivery (TBIRD) system to beam satellite data at 200 gigabits per second.

Speed isn’t the only potential attraction of optical interconnect technology, though. Replacing electrons with photons has been shown to reduce the interconnect power requirements. This, alongside the elimination of electrical resistance from these connections, will also mean a lot less waste heat is generated. A supporting statement in the PCI-SIG’s press release talked about embracing optical for “higher performance, lower power consumption, extended reach and reduced latency.”

PCI-SIG President and Chairperson, Al Yanes, indicates that the possible move to optical technology has been industry led. To increase momentum, Yanes has invited all PCI-SIG members to join the newly formed Optical Workgroup to press ahead with PCIe optical interconnect development.

roadmap to PCIe Gen7

Sadly, any PCIe optical transition isn’t going to arrive soon. The reason for this is that we already had PCIe Gen6 outlined back in 2022, and PCIe Gen7 is well into development, with a draft spec ready and an expected finalized specification release in 2025. It takes some time for these specifications to percolate into usage. Remember, the PCIe Gen4 spec was finalized way back in 2017, and yet it is the most widespread and popular high-performance interface today.