The race to scale artificial intelligence data centers isn’t won with GPUs alone. The network that connects them —fiber optics, transceivers, and silicon photonics— has become the quiet bottleneck of this decade. In this arena, GlobalFoundries (GF) and Corning have just made their move: both companies announced a collaboration to develop detachable fiber connectors compatible with GF’s silicon photonics platform. The goal is as simple to state as it is complex to execute: package optics (co-packaged optics, CPO) closer to the chip, while maintaining flexibility and serviceability in the fiber–PIC (photonic integrated circuit) link.
The centerpiece of the announcement is GlassBridge™, Corning’s edge-coupler (edge-coupler) based on glass waveguide technology, compatible with GF’s V-grooves. It’s complemented by another development in progress: a vertical detachable fiber-to-PIC coupler (vertically-coupled detachable fiber-to-PIC). Together, the message is clear: multiple forms of PIC-to-fiber connection, all detachable, and designed for co-packaging at large scale in scale-out and scale-up networks.
“Our collaboration with Corning represents a step forward in delivering next-generation connectivity for AI and machine learning,” emphasizes Kevin Soukup, senior vice president of silicon photonics at GF. “Corning’s latest-generation fiber, integrated into our silicon-verified platform, provides the performance and flexibility needed for dense, scalable optical packaging in AI data centers.”
“Combining GlobalFoundries’ silicon processing expertise with Corning’s leadership in optical interconnection opens new possibilities for AI infrastructure,” adds Claudio Mazzali, Global Research VP at Corning. “It’s a collaboration designed for an increasingly data-driven world.”
The first prototypes of this detachable connector —both the GlassBridge™ edge-coupler and the vertical variant— will be showcased at two industry events: the ECOC 2025 trade show (Copenhagen, Corning booth #2118) and the GF Technology Summit (Munich).
Why it matters: co-packaged optics needs “detachable”
Co-packaged optics (CPO) promises to reduce consumption and latency by bringing optical interfaces closer to the switching ASICs or accelerators: less copper, less conversion, fewer watts per bit. But CPO faces a practical core challenge: how to reliably, repeatedly, and maintainably attach fiber to an integrated PIC embedded in the chip package.
The industry has explored two main approaches to coupling:
- Grating couplers (vertical grating coupling): more tolerant and friendly with the assembly chain, but typically with higher optical losses and narrower bandwidth.
- Edge couplers (lateral coupling at the waveguide edge): lower loss and excellent bandwidth, but requiring stricter alignment tolerances and more demanding mechanics.
The GF–Corning announcement aims for the best of both worlds: low-loss edge-coupling with a detachable connector (GlassBridge™), and concurrently, a vertical detachable coupling option for those prioritizing tolerance and integration comfort. The term “detachable” is key: if a link degrades or a module fails, the entire package doesn’t need replacement; the fiber can be disconnected and reconnected as if it were an optical connector… but right at the chip edge.
What each part brings: silicon photonics + precision glass fiber
This collaboration leverages complementary expertise:
- GlobalFoundries provides the silicon photonics platform at industrial scale, with V-grooves for passive fiber alignment, high-volume manufacturing, and photonic IP blocks that already support CPO for scale-out/scale-up networks.
- Corning offers its ecosystem of glass, fiber, and connectivity: glass compositions and glass wafers for glass waveguides, IOX, laser processing, and Fiber Array Units (FAU) with ultra-precise core alignment to minimize insertion losses in demanding environments (AI and HPC).
GlassBridge™, as an integrated glass waveguide on a fiber-optic edge connector, acts as a “bridge” between fiber and PIC. Material mismatch —CTE, thermal stability— and the optical optimization of glass versus silicon are part of its appeal: aiming for a robust union that withstands temperature variation, is reproducible across batches, and is straightforward to handle manufacturing-wise, with potential for field replacement in data centers.
Technical context: AI pushes toward 800G, 1.6T, and beyond… copper can’t keep up
Major AI clusters have made interconnection the standout challenge. Moving from 400G to 800G and 1.6T per port is more than a DSP and modulation challenge: it’s a thermal budget issue that copper cannot satisfy. In switching and backplanes, CPO has been proposed for years as a way to reduce pJ/bit. In server racks, AOCs and pluggables face physical limits (length, latency, power) as clock domains synchronize and east-west traffic intensifies.
In this environment, a detachable coupling with low loss and high density offers several advantages:
- Lower the power overhead of the interface (fewer stages, less copper).
- Enhanced maintainability (easy replacement without reworking the entire module).
- Accelerated production (passive alignments via V-grooves and FAUs, eliminating the need for ultra-fine pick-and-place for each fiber).
- Enabling denser form factors in cabinets and motherboards.
In essence, it helps to address the power and latency budget constraints that currently challenge every AI deployment.
Why glass? Practical advantages of GlassBridge™ as an “edge-coupler”
Glass is carving out a space in optical packaging thanks to mechanical, thermal, and optical benefits:
- Thermal stability and low CTE: reduces misalignment risks over thermal cycling typical of a co-packaged package with hot chips.
- Precise fabrication: laser processing and glass compositions enable controlled geometries, tapers, and polished faces to facilitate low losses.
- Natural interface with FAUs: Corning controls everything from fiber to array, with core alignment designed to minimize losses at the matrix level (not fiber-to-fiber).
- Compatibility with V-grooves: GF’s platform foresees V-grooves in the substrate for seating and positioning of glass connectors without active alignment machinery.
The goal is not a laboratory record but a manufacturable industrial solution that can scale to hundreds of thousands of units, delivering yield and reliability akin to a foundry, with field reconfigurability that minimizes disruption.
Technical landscape: AI drives toward 800G, 1.6T, and beyond… copper isn’t enough
Large AI clusters have turned interconnection into a dominant concern. Moving from 400G to 800G and 1.6T per port presents more than DSP, modulation challenges — it’s a thermal budget issue that copper can’t satisfy. For switching and backplanes, CPO has been a candidate for reducing pJ/bit over years. In racks, AOCs and pluggables encounter physical limits (length, latency, power) as clock domains synchronize and east-west traffic increases.
A low-loss, high-density detachable coupling offers benefits like:
- Reducing power overhead per interface.
- Enhancing maintainability for rapid field replacement.
- Accelerating manufacturing, via passive alignment techniques and matrix-based fiber arrays.
- Enabling denser and more flexible form factors.
Overall, a solution that significantly helps in tackling the watt/bit and latency challenges facing AI data center infrastructure.
Why glass? Practical advantages of GlassBridge™ as an “edge-coupler”
Glass gains ground in optical packaging because of its mechanical, thermal, and optical advantages:
- Thermal stability and low CTE: lower risk of misalignment over thermal cycles in a co-packaged environment with hot chips.
- Manufacturing precision: laser machining and glass compositions enable controlled geometries, tapers, and polished faces that drive low-loss interfaces.
- Intuitive interface with FAUs: Corning manages everything from fiber to arrays with core alignment designed to minimize losses.
- Compatibility with V-grooves: GF’s platform plans V-grooves for straightforward mounting without active alignment machinery.
The aim is not a lab record but a scalable industrial solution capable of supporting hundreds of thousands of units, with yields and field flexibility suitable for large-scale deployment.
Two paths, same goal: detachable edge-coupled and vertically-coupled
The announcement references two families of detachable couplers:
- GlassBridge™ (edge-coupled): optimized for low-loss edge coupling, leveraging GF’s V-grooves and glass waveguides to improve tolerance and stability.
- Detachable vertical fiber-to-PIC: vertical coupling approach, historically more tolerant of misalignments and easier to automate, now designed for detachment for maintenance and replacement.
GF and Corning working on both options indicates a pragmatic strategy: there won’t be a single standard for all form-factors and loss budgets. Ecosystem players—hyperscalers, OEMs, switch manufacturers, accelerator vendors—will choose case by case based on loss, tolerance, density, and cost.
What could change in factory and data center (if the piece proves viable)
- Faster integration: with passive alignments and detachable connectors, assembly steps are simplified and shortened, boosting efficiency.
- More flexible operation: on-site replacement avoids full module swaps, reduces MTTR, and improves SLA.
- Long-term evolution: a detachable connector enables straightforward fiber/FOADM upgrades without redesigning the photonic board.
- Vendor diversification: separating connector, fiber, and PIC broadens sourcing, valuable in capacity-constrained markets (e.g., advanced packaging).
Where to see the demos: ECOC and GF Technology Summit
The upcoming demos —GlassBridge™ edge-coupled at ECOC 2025 (Copenhagen, #2118) and at the GF Technology Summit (Munich)— will serve as the initial gauge. The main technical questions likely to arise include:
- Insertion losses from fiber to chip to fiber.
- Tolerance to misalignments (lateral, vertical, tilt) and thermal cycles.
- Port density at the edge and within the fiber matrices (channels per module).
- Manufacturing yields and assembly times.
- Compatibility with relevant wavelengths and modes.
- Connect/disconnect cycles (mechanical reliability).
- Integration with CXL and next-gen rack topologies (from NICs and accelerators to CPO switch ASICs).
It’s notable that GF frames this solution within a comprehensive silicon photonics platform—proven in silicon and ready for CPO. In a market demanding volume and consistency, having a foundry with scale and quality behind the platform is as critical as a good optical design.
Strategic signals: supply chain and standardization
This collaboration is not only about technology; it’s also industry-oriented:
- Corning has a global footprint in glass/fiber and connectivity (from glass compositions to FAUs), with proprietary processes and metrology for ultra-high precision core alignments.
- GF provides fab capacity for silicon photonics and a bridge towards packaging and high-volume validation.
If this solution gains traction, it could push towards standardization of detachable interfaces for CPO—a still-evolving space where each loss and tolerance point translates to watts and euros at large AI campus scale.
Limitations and roadmap: what remains unsaid
As with any collaboration note, the announcement refrains from specific figures on loss or tolerance and does not specify compatibilities with mechanical formats (e.g., co-packaged in 51.2T / 102.4T switches or mid-board optics in accelerators). This is understandable: these are demonstrators. The next 12–18 months will reveal whether GlassBridge™ and the vertical detachable coupler withstand aggressive thermal cycling, vibration, fast switching, and the power budgets of 800G/1.6T per channel.
The disclaimer from GF highlights that these are prospective statements subject to risks and uncertainties. In other words, there’s a hall of continued development ahead.
Conclusion: a key piece for genuine optical deployment in the AI era
The performance leap for AI won’t go far if we keep pushing more copper over greater distances. CPO and silicon photonics are pathways forward—only if we solve their fine logistics: connecting fiber to chip with low loss, high density, manufacturing performance, and field reconfigurability. That’s precisely what GlobalFoundries and Corning are tackling with GlassBridge™ and the detachable vertical coupler.
If prototypes demonstrate controlled losses, reasonable tolerances, and solid mechanics, this will be among those discrete innovations that—though not headline-making—enable a single model to scale from 1,000 to 10,000 GPUs without exponential increases in watts/bit. As the industry already measures cost-per-token and latency-per-hop, few innovations are as impactful as uniting light with silicon in a balanced, scalable way.
Frequently Asked Questions
What is GlassBridge™ and how does it differ from a traditional grating coupler?
GlassBridge™ is an edge-coupler (based on Corning’s glass waveguide) compatible with V-grooves in GF’s platform. Unlike vertical grating couplers, edge-couplers typically offer lower loss and wider bandwidth. Corning’s approach adds the value of being detachable and leverages glass to enhance thermal and mechanical stability.
Why is it important that the fiber–PIC coupler be “detachable” for co-packaged optics (CPO)?
Because CPO brings optics right up to the chip, maintenance and replacement become more complex. A detachable connector allows for fiber–PIC link replacement without reworking the entire module, reducing MTTR and enhancing SLA. It also simplifies field upgrades.
How does this fit with GlobalFoundries’ silicon photonics platform?
GF’s platform already supports CPO for scale-out and scale-up networks and includes V-grooves for passive fiber alignment. The collaboration with Corning adds compatible detachable connectors (edge and vertical), leveraging Corning’s fiber and glass ecosystem— including FAUs with high-precision core alignment—and GF’s manufacturing capacity for high-volume production.
Where can these couplers be seen and what should a data center operator evaluate?
The demos will appear at ECOC 2025 (Copenhagen, #2118 booth by Corning) and the GF Technology Summit (Munich). Operators should look at insertion losses, alignment tolerances (lateral, vertical, tilt), power budget, durability over cycles, manufacturing yields, and compatibility with future form-factors for 800G/1.6T per channel or more.
via: GlobalFoundries