FADY MASOUD NEXT GENERATION COMPONENTS
Figure 2: IMDD optical pluggable architectures
with low insertion loss and efficient modulation in standard QSFP-DD and OSFP form factors. The DSP must deliver the essential benefits of coherent detection while reducing power, latency and complexity through simplified processing, lighter compensation and application-appropriate forward error correction (Figure 1). The result is a new middle ground for optical connectivity. Coherent lite can support high-loss intra-data centre links, campus scale-out and short DCI- style applications without carrying the full cost and power burden of long-haul coherent systems. It gives operators another tool as AI fabrics expand beyond simple rack-scale topologies. LPO: REMOVING THE DSP TO SAVE POWER While Coherent lite addresses links that need more optical performance, another innovation is attacking the power problem from the opposite direction. Linear pluggable optics (LPO) removes the DSP from the pluggable module entirely. Instead of retiming and equalizing the signal inside the optic, LPO relies on high-linearity analog components and the host switch ASIC to maintain signal integrity. This architecture can significantly reduce module power, heat, latency and cost, which is why LPO is attractive for dense AI fabrics where thousands of short links operate inside tight power envelopes. The trade-off is tighter dependency on the host. Without a DSP in the optical module, the electrical channel, PCB traces, drivers, TIAs, modulators and photodiodes must be carefully designed as a system. LPO
works best where reach is short, link conditions are controlled and the switch ASIC can shoulder more of the signal- processing burden. CPO: BRINGING OPTICS TO THE ASIC As data rates move from 1.6 T to 3.2 T and beyond, even highly optimized pluggables face a fundamental challenge: electrical loss between the switch ASIC and the front-panel module. At 224 G and future 448 G electrical lane speeds, long PCB traces consume power, reduce margin and complicate thermal design. Co-packaged optics (CPO) change the physical architecture. Instead of placing optics at the faceplate, CPO integrates optical components into the switch ASIC, reducing electrical trace length and improving power efficiency, bandwidth density and signal integrity. This proximity is essential as switching capacity scales, but it creates a reliability concern: lasers do not like the heat generated near high-power ASICs. That is why CPO architecture uses external laser sources in ELSFP form factors. Moving continuous-wave lasers to the cooler, serviceable front panel improves thermal management and field replaceability while supplying stable light to multiple silicon photonics engines (Figure 2). BUILDING THE RIGHT OPTICAL FOUNDATION FOR AI CONNECTIVITY The AI era is expanding the optical toolkit. Conventional coherent remains essential where reach and performance dominate. Coherent lite adapts coherent
principles for high-loss, shorter-reach data centre and campus links. LPO strips power and latency from short, controlled pluggable connections by eliminating the module DSP. CPO integrates optics with the switch ASIC to support the next leap in switch capacity, enabled by external laser sources that improve reliability and serviceability. Together, these approaches form an innovation continuum, enabling operators to match each link to the right balance of performance, efficiency, cost, and scale.
Fady Masoud is a Senior Director for Solutions Marketing at Nokia focusing on next-generation Intelligent Coherent Pluggable optics (ICE-X) and cloud / data centre interconnect solutions. His area of expertise is the architecture and requirements of next-generation optical networking infrastructure.
www.opticalconnectionsnews.com
11
ISSUE 44 | Q3 2026
Made with FlippingBook Annual report maker