As technology becomes more advanced, manufacturers can do a lot more to raise the stakes without running into major issues such as overheating, increased power consumption, and even just the size of high-end chipsets. Startup Lightmatter claims to have found a solution.
By using photonics instead of electrical wires, Lightmatter has the potential to eliminate bottlenecks and enable the creation of even more powerful chiplets. This may be the secret to making some of the best processors in the future.
Some chipset technologies, such as Intel Foveros 3D, allow multiple chips to be paired on the same substrate. These chiplets must then be connected using electrical wires. However, this results in flying electrons, which then cause higher temperatures and consume more energy. However, Lightmatter approaches this in a completely different way, replacing wiring with photonics. The startup spoke about its findings during Hot Chips 2022.
Electricity is fast, but light is faster. To make it work, Lightmatter introduced Passage, a “wafer-scale programmable photonic interconnect”. Using Passage, Lightmatter wants to connect different chips using nanophotonic waveguides instead of electrical wiring. Interconnected chiplets may include a CPU, GPU, memory chips, or ASICs.
“The passage consists of a 300mm Silicon Photonics wafer that includes lasers, optical modulators, photodetectors and transistors integrated into the platform,” said Nicholas Harris, founder and CEO of Lightmatter. “Because the Passage has lasers and transistors built in, the co-packaged chips don’t have to deal with any complex photonic transmit, receive, or switch circuit elements.”
The benefits of using this technology are numerous, including low signal loss, the ability of each tile to host multiple different chips, and a significant increase in throughput across the board.
Lightmatter teased that Passage allows for up to 96 Tbps of throughput per die. Communication between Passage and other systems via fiber optic arrays reaches a maximum speed of about 16 Tbps. According to Tom’s Hardware, AMD’s Infinity Fabric peaks at around 800Gbps, which is a huge difference.
Passage may also prove easier for manufacturers to use as it replaces proprietary technologies introduced by Intel and AMD. All you have to do is toss the device into the photonics aisle, and it will provide a link between them. However, silicon-based transistors will still need to be electrically coupled.
This technology is certainly one way to achieve the future of computing, and the potential increase in throughput is huge. However, Lightmatter isn’t the only company exploring photonics as a way to fight Moore’s Law, so it remains to be seen if the giants will turn to it or stick with their own solutions.