LPO and CPO: Where Optical Module Power Is Heading

The problem being solved

Every optical module contains a DSP that retimes and reshapes the electrical signal. That DSP is what allows a pluggable module to interoperate across vendors and across distances — and it is also a significant share of the module's power consumption.

As port speeds went from 100G to 400G to 800G, DSP power scaled roughly with bandwidth, and per-port power budgets started colliding with what a switch faceplate could cool.

LPO — linear-drive pluggable optics

LPO removes the DSP from the module and relies on the switch ASIC's SerDes to drive the optics directly.

• Power: substantially lower per port, since the DSP is gone
• Latency: lower, because there is one less retiming stage
• Form factor: still pluggable — the module remains field-replaceable, which matters enormously for operations
• Constraint: the link budget tightens, because there is no retiming to clean up the signal. Reach is shorter and interoperability between different vendors' switch and module pairs must be validated
• Best fit: short-reach, high-density links inside a data center hall

CPO — co-packaged optics

CPO goes further: the optical engine is moved onto the same package as the switch ASIC itself. There is no pluggable module at all.

• Power: the lowest of the three approaches — electrical traces from ASIC to optics become very short
• Density: the highest, because optics no longer consume faceplate space
• Constraint: optics become part of the switch. A failed optical engine is a switch-level service event, not a module swap. This changes field maintenance fundamentally
• Maturity: commercial deployments are growing but the supply chain is concentrated, and standards are still consolidating

Comparing the three approaches

| | Pluggable (with DSP) | LPO | CPO | |---|---|---|---| | Field replaceable | Yes | Yes | No | | Power per port | Baseline | Lower | Lowest | | Reach | Longest | Shorter | Short | | Interoperability | Highest | Needs validation | Vendor-defined | | Maintenance model | Swap module | Swap module | Service switch | | Maturity | Fully mature | Deploying | Early commercial |

What buyers should actually do

1. Do not defer current deployments waiting for LPO or CPO. Standard pluggable optics remain the right answer for essentially all reach classes and for any multi-vendor environment today.
2. Track LPO where density is the binding constraint — high-density 400G/800G leaf-spine links inside a hall.
3. Treat CPO as architecture, not procurement. If your next-generation switch platform is CPO-based, that decision is made with your switch vendor, years ahead, and it changes your operations model.
4. Plan the thermal budget of any speed upgrade explicitly. This is the practical near-term action: confirm that the faceplate can cool the modules you intend to install.

Canjin Technology supplies standard pluggable optics across all reaches and speeds, and follows the LPO and CPO roadmaps as they reach commercial maturity.