You do not need co-packaged optics (CPO) to scale data-center bandwidth. The main alternatives are conventional pluggable transceivers, lower-processing pluggables such as linear pluggable optics (LPO) and linear receive optics (LRO), on-board optics (OBO), and near-packaged optics (NPO). Each moves optical conversion or signal processing to a different point in the system, trading power, latency, bandwidth density, compatibility, serviceability, and deployment maturity in different ways. Optical circuit switching (OCS) can complement these choices at the network-fabric level; it is not simply another type of transceiver.
What can you use instead of co-packaged optics?
Co-packaged optics places optical engines close to, or alongside, the switch ASIC in a shared package. The aim is to reduce the distance high-speed electrical signals must travel before becoming optical signals. That can help address power, signal-integrity, and density pressures as switch bandwidth grows. But moving optics closer to the ASIC also makes the package, board, cooling, optical interface, and service model more tightly interdependent.
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The alternatives sit at different points along that integration path. A front-panel pluggable keeps the optical module outside the switch and replaceable. LPO and LRO change how much signal processing happens inside the pluggable. OBO moves optical engines onto the host board. NPO moves them inside the switch, close to but separate from the ASIC. These are not interchangeable products: a system designed for one approach may not accept another without compatible hardware and signal handling.
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| Approach | Where optics sit | Signal processing choice | Practical trade-off |
|---|---|---|---|
| Fully retimed pluggable (FRO) | Replaceable module at the front panel | Transmit and receive retiming and processing in the module | Mature, broadly supported, modular; processing adds power and latency |
| Linear receive optics (LRO/HRO) | Replaceable module at the front panel | Retiming limited to the transmit direction | Can reduce module power and latency versus fully retimed optics; requires a suitable host design |
| Linear pluggable optics (LPO) | Replaceable module at the front panel | Module DSP removed; host ASIC handles signal correction | Potentially lower module power and latency, but depends on compatible host SerDes and signal integrity |
| On-board optics (OBO) | Optical engine on the host board | Depends on the design | Shorter electrical path than front-panel modules without direct ASIC co-packaging |
| Near-packaged optics (NPO) | Inside the switch, near but separate from the ASIC | System-specific, closely co-designed | Greater integration while retaining separation from the ASIC package; serviceability and thermal design require attention |
| Co-packaged optics (CPO) | Alongside or within the ASIC package | Closely integrated with the switch design | Strongest integration in this comparison, with corresponding packaging and service dependencies |
“More integrated” does not automatically mean “better.” The right choice depends on whether the system is constrained by module power, board routing, signal reach, available switch platforms, or the ability to replace components quickly. The architecture also needs to fit the network’s deployment and maintenance practices.
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- 800Gbps High-Bandwidth Connectivity Provides 800Gbps optical networking capability for next-generation Ethernet infrastructure, AI clusters, GPU computing, cloud data centers and high-performance computing applications.
- OSFP DR8 Gen2 Architecture Features an OSFP package with DR8 Gen2 optical architecture, providing 8-channel parallel optical connectivity for high-density 800G network deployments.
- Up to 500m Transmission Distance Designed for up to 500m transmission over single-mode fiber, making it suitable for longer-reach data center connections between racks, rows and network switching infrastructure.
- 1310nm Single-Mode Fiber Uses a 1310nm optical wavelength and single-mode fiber (SMF) architecture for high-speed parallel optical transmission over longer distances. Typical DR8 implementations use MPO-based parallel fiber connectivity.
- Silicon Photonics for AI & Data Center Applications Based on Silicon Photonics (SiPh) technology, the Gen2 design is positioned for high-density optical interconnects in AI computing, GPU clusters, HPC systems, cloud data centers and 800G Ethernet networks.
How the alternatives work
Fully retimed pluggable optics: the modular baseline
A fully retimed optical module performs transmit and receive retiming and processing within the module. That processing can help make the optical link robust across different host and link conditions. The module sits in a front-panel port, so operators can replace it without replacing the switch board or ASIC. Nokia describes this approach as robust, easy to deploy, and broadly supported.
The trade-off is that signal-processing circuitry in the module consumes power and contributes latency. The module also occupies faceplate space, and the electrical connection between the switch ASIC and front-panel module remains part of the signal path. This familiar design is a sensible reference point when comparing newer options, but its maturity does not make it the most power- or density-efficient choice for every system.
LRO/HRO: retiming only in the transmit direction
Linear receive optics, also called half-retimed optics (HRO), limit retiming to the transmit direction rather than using it in both directions. Nokia characterizes LRO as reducing power and latency compared with fully retimed optics. The module remains pluggable, but its processing arrangement changes what the host must do to support the link.
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LRO is therefore a compromise within the familiar front-panel form factor, not a universal substitute that can be inserted into any port. Buyers need to check the switch platform’s supported optics and host signal handling. The exact reduction in power or latency depends on the system; the available sources do not provide a neutral, directly comparable test across platforms.
LPO: move signal correction to the host
Linear pluggable optics removes the module’s digital signal processor (DSP) and relies on the host switch ASIC to perform signal correction. With less processing in the module, LPO can reduce module power and latency. Nokia describes its ICE-D 1600G DR8 LPO transceiver as a product example and describes intra-data-center optical links above 1.6 Tb/s; that product example does not establish pricing, broad deployment, or compatibility with a particular switch.
The host’s SerDes and signal-correction capabilities become critical. LPO demands a compatible switch and careful signal-integrity design; it is not a drop-in replacement for fully retimed optics in every port. In practical terms, the lower-processing module shifts some of the system’s burden rather than making signal correction disappear. Teams evaluating LPO should confirm both the optical module support and the switch vendor’s host-side requirements before planning a deployment.
Ciena’s February 25, 2026 announcement introduced its Vesta 200 6.4T CPX pluggable optical engine, describing retimer-free, linear-drive operation and an IEEE 802.3dj-compliant optical interface. Ciena claims “up to 70%” power savings versus traditional retimed options for this product and comparison. That is a vendor-stated maximum for the named design, not a general LPO result or an independent head-to-head benchmark. Ciena also describes a standards-based ecosystem; that wording should not be mistaken for evidence that every related specification or implementation is complete and interoperable.
OBO: put optical engines on the board
On-board optics places optical engines on the host board rather than in removable front-panel modules or directly beside the ASIC in its package. The shorter electrical path can help relieve board-level signal-integrity and routing constraints while avoiding direct co-packaging. A 2025 technical review characterizes OBO as a middle ground and notes demonstrated use in high-performance computing (HPC).
The same review reports a multi-source agreement defining 400 Gb/s and 800 Gb/s modules. Those figures describe the agreement’s specified module rates; they do not demonstrate broad deployment or guarantee that a particular board supports them. Moving optics onto a board also changes how components are accessed and repaired compared with a front-panel module. The board and system design must account for that integration.
NPO: optics inside the switch, but separate from the ASIC
Near-packaged optics places optical interfaces inside the switch, close to but separate from the switch ASIC. It shortens the electrical path relative to front-panel pluggables without placing the optical engine in the ASIC package itself. This is a closer-integration option, not merely a different module format.
Nokia notes that NPO and CPO usually require close co-design. They may use pluggable external light sources (ELS), which can help with thermal management, reliability, and serviceability. An external light source does not make every other integrated optical component field-replaceable: that depends on the specific system design. Ask vendors how a failed optical engine, light source, fiber connection, or switch assembly is diagnosed and replaced.
Are pluggable optics good enough for AI data centers?
They can be. “AI data center” describes a workload and deployment context, not a single required optical architecture. A fully retimed pluggable may be attractive where compatibility, established operations, and faceplate replacement matter most. LPO or LRO may suit systems designed to use less retiming, if the switch can handle the required signal processing. OBO, NPO, or CPO may become more relevant when electrical reach, routing, or front-panel density is a limiting factor.
The decision is not simply whether the network needs more bandwidth. It is whether a specific switch generation can deliver that bandwidth within the available power, cooling, board, and maintenance envelope. A lower-power module does not, by itself, establish lower total system power: the host may take on additional signal-correction work, and the complete switch design determines the system result. Nor do vendor figures from different products constitute a fair ranking when their conditions and comparison bases differ.
Rank #2
- 800Gbps High-Speed Transmission Supports 800Gbps Ethernet connectivity with an 8-channel parallel optical architecture, designed for high-bandwidth AI clusters, cloud computing and next-generation data center networks.
- OSFP VR8 Form Factor Features the OSFP package and VR8 optical configuration, providing a high-density 800G optical solution for compatible Ethernet switches, routers and data center networking equipment.
- 30m / 50m Short-Reach Performance Designed for short-distance multimode fiber links, supporting up to 30m over OM3 and 50m over OM4/OM5, making it suitable for rack-to-rack and in-row data center connections.
- 850nm Multimode Optical Interface Uses an 850nm optical wavelength with multimode fiber (MMF) for high-speed short-reach optical transmission. The MPO interface supports high-density parallel fiber connectivity.
- Designed for AI & Data Center Networks Ideal for AI computing clusters, GPU networks, HPC systems, cloud data centers and 800G Ethernet infrastructure, providing high-bandwidth optical connectivity for demanding computing environments.
For context, Cisco announced on October 12, 2026, that its Silicon One G302 is a 51.2T top-of-rack switch planned to begin shipping before the end of 2026. Cisco and NVIDIA also announced plans to develop an Ultra-Dense Small Form Factor Pluggable (USFP) capable of 400 Gb/s per lane. Cisco says the planned design is expected to provide four times the bandwidth density and 1.3 times the power efficiency of 200-Gb/s-per-lane optics while retaining serviceability and deployment flexibility. Those are Cisco’s claims about a planned design, not independent results for a shipping product; an open industry specification is expected, not established by the announcement as already complete.
The announced USFP effort illustrates why pluggables should not be treated as a technology that has reached a fixed ceiling. A pluggable form factor can evolve while keeping serviceability as a design aim. It also illustrates why roadmap language matters: a planned design and a switch with a stated future shipping window are not the same as a product whose availability and compatibility have been confirmed for a particular deployment.
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Power and latency
Removing retiming or DSP stages can lower module power and latency, but the host may need to take on more signal-correction work. Compare the complete switch and link configuration, not module power alone. Ask whether a quoted figure is a measured result, a vendor estimate, or a maximum claim; what product and comparison it concerns; and whether it includes the host-side changes needed to support that architecture.
Bandwidth density and electrical reach
Moving optical conversion closer to the ASIC shortens the electrical path and can ease board-level routing and signal-integrity constraints. That is the central architectural rationale for OBO, NPO, and CPO. Greater proximity also increases the importance of coordinated electrical, optical, thermal, and packaging design. A density claim should be interpreted in the context of the specific port, switch, and optical interface rather than assumed to apply across platforms.
Compatibility and interoperability
For LPO, verify host SerDes capability and the supported signal-correction path. For NPO and CPO, ask how the optical engine, ASIC, packaging, thermal design, and external light source fit together. A standards-based interface or multi-source agreement can help establish common expectations, but an announced or planned specification is not a completed standard, and a stated standard does not by itself prove that two specific products interoperate.
Serviceability and deployment
Front-panel pluggables preserve the familiar ability to replace a module at the faceplate. Board-mounted and more integrated approaches change where components are located and how they can be serviced. For NPO or CPO systems, determine which pieces are replaceable in the field, whether repair requires removing the switch, and how the vendor handles thermal or optical failures. Do not assume an integrated component is field-replaceable unless the specific design says so.
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Maturity and evidence
Conventional pluggables are described as mature and broadly supported. Newer approaches have different product, specification, and availability timelines. Separate a product example from evidence of broad deployment, a sampling announcement from general availability, and a roadmap from a shipping product. Across the architectures discussed here, the cited material does not provide a neutral test of all approaches under the same system conditions, so it cannot support a universal performance ranking.
Where optical circuit switching fits
Optical circuit switching is a fabric-level choice, not a replacement for every transceiver link. TrendForce describes OCS as replacing electrical with optical switching for large, dynamic AI networks and treats it as complementary to CPO. That places OCS at a different decision point: it changes how optical paths are switched across a network fabric, while pluggables, LPO, OBO, NPO, and CPO concern where optical conversion and related processing happen in a device or link.
A network can therefore consider an OCS switching plane alongside a choice of endpoint optics. The relevant question is not “OCS or LPO?” as if the two were competing modules. It is whether a fabric-level optical switching approach addresses the network’s topology needs, and separately which optical interface architecture fits the switch hardware and operational requirements.
What current product claims do—and do not—show
NVIDIA’s current Spectrum-X Ethernet Photonics product page states capacity of up to 409.6 Tb/s and lists availability in the second half of 2026. This is a CPO example, not an alternative to CPO. It provides a current reference point for the scale vendors are targeting, but a stated maximum capacity and availability window do not establish how a particular deployment will perform.
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Jensen Huang, NVIDIA’s founder and CEO, said in the March 18, 2025 announcement: “AI factories are a new class of data centers with extreme scale, and networking infrastructure must be reinvented to keep pace.” That is the company’s strategic view of the problem, not independent evidence that one optical architecture is best for every network. Similarly, Ciena’s February 25, 2026 announcement quotes LightCounting CEO Vladimir Kozlov: “Adoption of CPO has started. The next priority for operators is development of a competitive CPO ecosystem.” This describes an ecosystem priority; it does not quantify adoption share or establish comparative performance.
How to choose an architecture for a real deployment
- Start with the bottleneck. Identify whether the limiting factor is port bandwidth, module or switch power, signal reach, board routing, front-panel density, or maintenance access. “Scaling bandwidth” can mean different constraints at different levels of the system.
- Check the switch platform before shortlisting optics. Confirm supported module types, host SerDes and signal-correction requirements, interface rates, and any platform-specific compatibility list. This is essential for LPO and for tightly co-designed NPO or CPO systems.
- Compare the whole-system trade-off. Ask for module and system power, latency, link conditions, cooling assumptions, and the exact baseline for each claimed improvement. Treat vendor maxima as product-specific claims, not expected savings for every configuration.
- Map the service procedure. Establish which elements are replaceable, where repairs happen, what spare parts are needed, and what happens if an optical engine or external light source fails. Compare this with the faceplate replacement model of pluggables.
- Separate what exists from what is planned. Verify whether a product is shipping, sampling, or on a roadmap; whether its specification is published or still expected; and whether the needed switch and module are available together in the relevant region and configuration.
- Validate with the actual workload and topology. Use a representative system-level evaluation before making an architecture decision. A headline bandwidth figure alone does not show application performance, power efficiency, or resilience under the conditions of a specific network.
Bottom line
For a deployment that prioritizes modularity and established support, conventional retimed pluggables remain the straightforward alternative to CPO. LRO and LPO reduce processing in the module, but shift more importance to host compatibility and signal handling. OBO and NPO shorten the electrical path through closer integration, while changing board design and serviceability. OCS addresses network-fabric switching and can complement, rather than replace, these link choices. Choose against the actual system bottleneck and verified platform support—not a vendor’s headline number in isolation.
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