What is co-packaged optics

Co-packaged optics (CPO) is a technology that integrates optical components directly alongside electronic components, such as switch ASICs or AI accelerators, within the same package to reduce power consumption, latency, and improve bandwidth density.

What Co-Packaged Optics Is

Co-packaged optics (CPO) is an advanced design approach where optical components like lasers, photodetectors, and photonic engines are integrated directly with electronic circuits such as Application-Specific Integrated Circuits (ASICs) or GPUs in the same package or on the same substrate . Unlike traditional pluggable optics, which connect to switches via long PCB traces, CPO places the optical engine within millimeters of the ASIC, drastically reducing electrical path length, signal loss, and power consumption . This integration can be implemented using 2.5D silicon interposers or 3D die stacking techniques, including through-silicon vias or hybrid bonding .

Benefits of CPO

1. Power Efficiency: By shortening electrical paths and eliminating the need for DSP retimers, CPO can reduce power consumption by up to 70% compared to pluggable transceivers, which is critical for energy-intensive data centers .
2. Higher Bandwidth: Direct integration allows higher SerDes rates (200 Gbit/s or more) and supports bandwidth densities that pluggable optics cannot achieve, enabling next-generation data centers to handle massive AI and HPC workloads .
3. Reduced Latency: The proximity of optical and electronic components improves signal integrity and reduces latency, enhancing performance for high-speed data transfer .
4. Scalability: CPO supports high-density fiber routing and multi-node connectivity, making it suitable for hyperscale and AI-focused data centers .

How CPO Works

CPO integrates optical engines directly adjacent to the ASIC, collapsing electrical distances to millimeter scales. This allows optical signals to be transmitted efficiently without long copper traces, reducing insertion loss and energy per bit . The technology leverages chiplets and 3D-IC integration, enabling different dies (e.g., older CMOS nodes for optics and advanced nodes for ASICs) to coexist in a single package, optimizing cost, yield, and performance .

Challenges

Despite its advantages, CPO faces several engineering challenges:

• Thermal management: Placing photonics near hot ASICs increases heat density.
• Fiber attachment: High-density fiber harnesses require precise alignment and handling.
• Yield and serviceability: Co-locating optics and electronics complicates testing, repair, and field deployment .

Applications

CPO is particularly relevant for AI clusters, hyperscale data centers, and high-performance computing, where massive bandwidth, low latency, and energy efficiency are critical . It represents a shift from traditional pluggable optics toward integrated, high-density optical-electrical solutions that can meet the demands of next-generation networks. In summary, co-packaged optics is a transformative approach that brings optics and electronics closer together, enabling higher performance, lower power consumption, and scalable bandwidth for modern data-intensive applications .