NVIDIA's new Spectrum-X Ethernet: silicon photonics enters the chat, a game changer for AI

NVIDIA has just unveiled more details on its new Spectrum-X Ethernet Photonics interconnect, using next-gen silicon photonics replacing the traditional optical interconnect, and it's a "game changer" for AI.

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During the recent Hot Chips 2025 event, NVIDIA presented its next-gen Spectrum-X Ethernet Photonics interconnect, showing some rather huge improvements in scaling AI factories, and making sure the new interconnect will be an effective and powerful replacement of the traditional optical interconnect.

NVIDIA went into detail about the need of co-packaged photonics, and how massively it can scale AI factories, with the company noting that AI factories use around 17x more optics power compared to a traditional cloud data center, mostly because of the increased in GPU clusters that need dozens of optical transistors in order to talk to other GPUs.

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This makes networking optics cost around 10% of the total compute power of an AI factory on their own, and with the amount of AI servers and AI clusters being made, purchased, and built, NVIDIA wants in on that business with the use of its powerhouse Spectrum-X Ethernet Photonics.

NVIDIA's new Spectrum-X Ethernet Photonics is the world's first with 200G/SerDes co-packaged optics, which is the cutting-edge standard in electrical signaling.

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The new Spectrum-X Ethernet Photonics compared to pluggable transceivers, offer improved signal integrity and lower DSP requirements. This is because the photonic engine (PIC) is right beside the switch ASIC.

This means there's no need for long PCB traces, as well as a massive decrease in laser counts, with a 1.6Tb/s link dropping from eight lasers down to just two, resulting in reduced power consumption and higher transfer reliability.

NVIDIA's new CPO was co-invented with its ecosystem partners, with hundreds of patents and licensed to partners, with the Silicon Photonics CPO chip packing an ultra-high 1.6T transfer, with MRMs (Micro-Ring Modulators) on board. This results in higher bandwidth with a lower footprint and less power used.

Spectrum-X Ethernet Photonics is also the world's first 3D-stacked silicon photonics engine made on TSMC, as NVIDIA partnered with TSMC on silicon photonics.

NVIDIA's new silicon photonics inside of a data center is up to 3.5x more power efficient, 10x higher resoliency, and 1.3x faster time to operation compared to the optical standard. This is the game changer for AI compute, which can scale incredibly fast and high once silicon photonics is the mainstream interconnect.

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The company showed off a full-scale switch with integrated photonics, the new NVIDIA Spectrum-6 102T, the new flagship offering from NVIDIA. We can expect:

• 2x throughput
• 63x signal integrity
• 4x fewer lasers
• 1.6x bandwidth density
• 13x better laser reliability
• Replaces 64 separate transceivers

NVIDIA's new foray into silicon photonics has been a long time coming, but its first steps are here with a bang. NVIDIA Photonics will feature radically reduced power consumption, easier scaling, and performance boosts in interconnect by using the power of photonics. Co-packaged silicon optics feature 3x higher GPU under ISO power and 4 x reduction in the lasers required.

This means that there's far more power available to the chip, and can be moved away from networking to the actual clusters of GPU on the chip, providing more performance.

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The scale out of co-packaged optics networking switches to scale AI factories to millions of GPUs is coming, with new Spectrum-X Ethernet Photonics' roll out, with up to 512 ports of 800G