Co-Packaged Optics (CPO) foundry roadmaps — breaking down TSMC, Intel, Samsung, and GlobalFoundries' approach to next-generation scale-up connectivity

The requirements of AI clusters have made optical interconnections practical for scale-out connectivity, but as bandwidth requirements increase, optical connectivity is becoming viable for scale-up connections. As a result, the industry is moving optical interfaces closer to CPUs and GPUs, from the front-panel transceiver to the package itself through co-packaged optics (CPO), and eventually directly into the processor package.

Optical connectivity has been used for decades, as electrical links cannot efficiently and reliably transmit data over long distances at high data transfer rates. However, the cost and complexity of optical components limited their use to long-reach connections.

The importance of CPO is rising because electrical interconnects are no longer scaling as quickly as AI processors, and feeding thousands of accelerators within a data center requires an exponential increase in communication bandwidth. In a traditional optical networking architecture, the processor or switch ASIC communicates electrically with a pluggable optical transceiver located at the front panel of a server or switch. However, as signaling speeds climb to 200 Gb/s - 400 Gb/s per lane and beyond, transmitting electrical signals over long copper PCB traces on a motherboard becomes increasingly inefficient due to higher insertion loss, greater power consumption, and tighter signal integrity requirements.

While technically possible, it demands the use of better materials, retimers, complex compensation processing, and equalization circuitry, which increases the cost of server infrastructure and its power consumption. CPO moves optical engines next to the processor or switch ASIC to shorten the electrical path before signals are converted into light, which means lower power consumption per transmitted bit, increased bandwidth density, and predictable scalability. As a result, CPO is increasingly viewed as a necessary technology for next-generation AI infrastructure.

Because AI is viewed as a major megatrend, CPO is set to become ubiquitous; there are dozens of companies working in the CPO ecosystem, including foundries, OSATs, optical I/O startups, laser manufacturers, fiber suppliers, packaging houses, and networking vendors.

As there are so many vendors pursuing different goals with different strategies, for this story, we are going to limit ourselves only to companies that actually produce things and whose roadmaps reflect their technological capabilities. So far, only four foundries have publicly articulated meaningful CPO manufacturing strategies: Intel Foundry, GlobalFoundries, Samsung Foundry, and TSMC.

The four companies each represent four different CPO strategies and have very distinct plans for the future, so their plans and capabilities may not be directly comparable. Nonetheless, reviewing their offerings gives us an idea about where the industry is going from the perspective of actual foundries.

TSMC: COUPE for everything

TSMC has historically been absent from the optical connectivity market as a product supplier. However, having worked on silicon photonics for many years, it now has the broadest ecosystem and manufacturing roadmap with its Compact Universal Photonic Engine (COUPE).

TSMC's silicon photonics technology roadmap currently has three stages that span from a 1.6 Tbps optical engine with conventional pluggable optics to a 12.8 Tbps optical engine located within a processor package. The COUPE roadmap is tightly coupled with the company's advanced packaging technologies and the evolution of the company's micro-ring modulators (MRMs) that modulate light and directly impact performance. As a result, several TSMC customers (e.g., Nvidia) plot their silicon photonics strategies around the evolution of COUPE.

The first phase of the roadmap — called COUPE on PCB — relies on a COUPE that bonds a 65nm electronic integrated circuit (EIC) with a photonic integrated circuit (PIC) using the company's SoIC-X bonding technology. The initial implementation targets OSFP (Octal Small Form-factor Pluggable) optical modules and delivers 1.6 Tbps of bandwidth (2x the throughput of copper Ethernet solutions, along with 2x the power efficiency compared to copper). Therefore, the first-gen COUPE is out of the scope of this article. TSMC says the SoIC-X interface features very low impedance and enables lower power consumption at high signaling speeds.

The second generation — dubbed COUPE on substrate — marks TSMC's transition from conventional pluggable optics to co-packaged optics (CPO). In this stage, COUPE is integrated with the company's chip-on-wafer-on-substrate (CoWoS) advanced packaging technology and co-packaged with a network switch ASIC. This architecture enables motherboard-level optical interconnects with aggregate bandwidth up to 6.4 Tbps, 2x power efficiency, and 10x lower latency compared to existing pluggable solutions, which is fantastic for a variety of applications, such as NVLink, Ethernet, and InfiniBand switches.

The third phase — called COUPE on interposer — pushes silicon photonics even closer to compute dies: a 12.8 Tbps optical engine is integrated directly into the processor package to enable ultimate bandwidth and scalability. Beyond doubling bandwidth again, the company expects the architecture to offer 5x power efficiency and 20x lower latency compared to pluggable solutions used today. That will make it particularly attractive for use by hyperscalers that build clusters consisting of thousands of accelerators. Unfortunately, TSMC characterizes this phase as exploratory and has not disclosed its commercialization timeline.

The main agenda of COUPE is to move the optical engine as close to compute as possible. However, there is another dimension in TSMC's silicon photonics strategy: the evolution of the photonic devices themselves, the MRMs integrated into PICs. The company plans to bring the world's first 200 Gbps/lane (wavelength) micro-ring modulator into production in 2026 and then continue scaling the technology with 400 Gb/s MRMs, additional optical wavelengths, and denser fiber-array integration. This evolution is expected to increase COUPE’s bandwidth density from 0.5 Tb/s/mm in 2026 to 4 Tb/s/mm by 2030, providing an 8x improvement over four years.

It is noteworthy that TSMC presents the MRM roadmap separately from the evolution of COUPE packaging, which suggests that advances in micro-ring modulators represent an independent technology roadmap for the photonic integrated circuit (PIC), rather than being tied to a specific packaging generation. This potentially means that future COUPE products could adopt newer generations of MRMs regardless of whether the optical engine is mounted on a PCB, package substrate, or silicon interposer, although the latter will probably deliver the greatest system-level benefits by minimizing the electrical distance between compute dies and optical interfaces.

Intel: Optics for CPUs, GPUs, DPUs, and accelerators

Intel has been shipping various products with optical interconnections for decades and even attached its silicon photonics solutions to Xeon and Xeon Phi processors in the mid-2010s. Today, Intel's public CPO roadmap is less explicit than TSMC's, but its direction is fairly clear: move optical I/O directly next to CPUs, GPUs, accelerators, and eventually other compute chiplets. Meanwhile, so far, Intel has not unveiled plans to use its CPO technology for switches.

Intel's CPO strategy is largely focused on its Optical Compute Interconnect (OCI) chiplet, which is a self-contained optical I/O subsystem packing both EIC and PIC that can be co-packaged with any compute device using a PCIe interface to enable high-performance optical connectivity. Intel demonstrated the first OCI in 2024. That prototype implementation used 64 PCIe 5.0 lanes at 32 GT/s in each direction to connect to the host and provided 4 Tbps of bidirectional optical bandwidth over eight fiber pairs over a distance of up to 100 meters. Each fiber carried eight DWDM wavelengths spaced at 200 GHz, and every wavelength (lane) transported about 32 Gbps (8 FPs × 8 WLs × 32 Gbps = 2,048 Gbps in each direction).

The 2024 OCI implementation is good for testing the technology, but with rather slow 32 Gbps lanes, it has not been adopted commercially. Meanwhile, this technology has already been proven and demonstrated. Intel is currently working on its next-generation OCI with 200G/lane PICs to support 800 Gbps and 1.6 Tbps applications, though it is unclear when it is set to be available, as Intel has not yet disclosed an equivalent to TSMC's MRM roadmap.

It should be noted that future OCI implementations supporting bandwidth of 10s of terabits per second could interface with compute dies using next-generation PCIe 6.0 interfaces or even native die-to-die UCIe links when integrated into commercial products. Furthermore, Intel can naturally integrate OCI chiplets using its advanced packaging technologies to ensure high performance and low power.

As noted above, Intel's focus with OCI has always been its integration with CPUs, GPUs, DPUs, accelerators, or other compute devices, but not necessarily switches. It remains to be seen whether Intel's next-generation AI hardware roadmap will include switching silicon, but for now, it does not seem that the company is targeting optical switches with its OCI chiplets. Since OCI is protocol-agnostic, limiting it to compute devices seems like an artificial limitation, though we have little indication about Intel's reasoning behind the decision.

Samsung Foundry: Addressing everything

Samsung Foundry's silicon photonics strategy is arguably the most comprehensive among leading foundries. Unlike Intel, whose CPO roadmap is focused on its OCI chiplet for integration with compute devices, or TSMC, whose COUPE optical engine is another major ingredient of its foundry platform, Samsung intends to offer all types of optical connectivity devices, starting from pluggable transceivers in 2026, to switch CPO later on, and all the way to optical engines on the interposer of a processor package in 2030. Unfortunately, Samsung does not publicly provide a lot of information about its plans, so our main source of information will be SF's slide from a conference published by SemiVision.

This year, Samsung Foundry intends to offer a merchant PIC platform that relies on an EIC and a PIC mounted side by side on a PCB for conventional pluggable optics. The PIC will support 100 Gbps-class optical interfaces using CWDM technology, which is good enough for traditional pluggable optical transceivers (though Samsung does not specify the exact implementation), so there's no indication of CPO here.

In 2027, Samsung Foundry intends to catch up with TSMC's first-gen COUPE and offer an optical engine that stacks an EIC on top of a PIC using thermo-compression bonding (TCB). Samsung expects energy efficiency of this generation to improve from approximately 10 pJ/bit for its initial PIC platform to 5 pJ/bit, though Samsung has said nothing about bandwidth or latency. Samsung's TCB-based OE seems to be an intermediate product between merchant PICs and true CPO, so it will generally address onboard optics and pluggable transceivers.

By 2028, SF intends to move optical engines to the substrate of Ethernet or InfiniBand switch ASICs, which will be its first true CPO. The company intends to adopt hybrid copper bonding (HCB) with 10 µm pitches for its OEs to improve bandwidth density. Based on the slide from the roadmap, to address next-generation switches, Samsung is poised to increase optical lane speeds from 100 Gbps to 200 Gbps and ultimately 400 Gbps, although the company does not disclose when exactly each speed bin will be introduced (though it looks like 400 Gbps will come in 2029 – 2030) as well as the underlying modulator technology or other device-level details behind this scaling.

In 2029, Samsung Foundry will finally integrate its optical engine on an interposer next to CPU/GPU/XPU or other compute device, which will reduce energy consumption to 2 pJ/bit while providing extremely high bandwidth. Samsung calls this 'CPO Turnkey,' which implies that such integration will require its own packaging technologies. The next step in Samsung's roadmap is called 'next-generation CPO Turnkey,' and it integrates virtually the entire optical subsystem — including lasers — alongside compute and memory, which will be its ultimate CPO offering expected by 2030 and onwards.

While Samsung Foundry's ultimate goal to offer highly integrated turnkey CPO solutions is clear, the company also intends to offer two merchant platforms for pluggable optical transceivers, perhaps to de-risk development of its future products and to capitalize on the high demand for optical connectivity that exists today and will continue going forward.

GlobalFoundries: A bespoke vendor-agnostic OCI-MSA CPO platform

Unlike Intel Foundry, Samsung Foundry, and TSMC, GlobalFoundries does not produce or intend to produce AI processors, switch ASICs, or advanced packages. Instead, it aims to become a merchant co-packaged optics provider that will produce and sell bespoke CPO solutions that enable optical connectivity (including OCI MSA connectivity) for processors made by other chipmakers.

GF's silicon photonics effort dates back to the IBM Microelectronics acquisition in 2015, which brought IBM's silicon photonics technology and engineering teams into the company. Over the years, GlobalFoundries has expanded its silicon photonics capabilities into what eventually became the GF Fotonix platform and, more recently, the company acquired AMF and InfiniLink to further strengthen its production and design capabilities.

The key element of GlobalFoundries' CPO strategy is its Silicon photonics Co-packaged Advanced Light Engine (SCALE) platform that combines photonic IP, advanced packaging technologies, and a reference optical engine architecture that includes EIC and PIC. Unlike Intel's OCI chiplet, SCALE allows GF's clients to customize optical engines in accordance with their needs and have them manufactured by GF.

Under the program, GlobalFoundries manufactures the PIC and EIC using its own process technologies and then packages them into an OCI MSA-compliant optical engine using its methods. If the EIC requires a leading-edge node that GF does not have, it could instead be fabricated by another foundry and then integrated by GF. Customers then co-package the optical engine alongside their own switch ASICs or AI accelerators.

For now, SCALE supports both CWDM and DWDM transmission using qualified 50 Gbps and 100 Gbps MRMs, integrated photodiodes, and coupled-ring resonators. The platform has demonstrated bidirectional operation with up to 16 DWDM lanes per fiber, which theoretically opens doors to optical links with up to 1.6 Tb/s of bandwidth per direction. On the integration side of things, it supports advanced 2.5D and 3D integration using TSVs and copper bonding with pitches ranging from 110 µm to below 45 µm, which is good enough for integration using CoWoS-S and CoWoS-L technologies.

Just like Intel with its OCI, GlobalFoundries does not necessarily tie its SCALE CPO customers to its silicon or packaging technologies. Furthermore, the company allows its clients to customize their optical engines while retaining compatibility with the OCI-MSA requirements.

The future of CPO

Co-packaged optics (CPO) is set to become a key technology for next-generation AI infrastructure as conventional electrical interconnects struggle to keep pace with the bandwidth demands of rapidly developing AI processors.

Among foundries, TSMC, Intel, Samsung Foundry, and GlobalFoundries have each developed distinct CPO strategies that range from merchant optical engines to optical I/O chiplets and vertically integrated CPO platforms.

Given the different capabilities of the contract chipmakers, their roadmaps differ significantly in both scope and implementation, with some companies trying to lock in customers with a proprietary platform and others offering different degrees of freedom.

However, they all share the same objective: move optical interfaces progressively closer to compute dies to reduce power consumption, increase bandwidth density, and lower latency for the next generation of AI systems that will require considerably more bandwidth than today's clusters.