Interconnection Key issues
Power consumption, latency and signal integrity
Electrical signalling at high data rates uses a lot of power. Optical signalling consumes much less power, which is a crucial advantage for high-performance applications, AI and datacentre systems. Long electrical interconnect paths, such as those in racks or between chips/modules, also generate latency. Co-packaged optics (CPO) or chiplet-based photonic integration lowers latency by reducing the distance between optical components and the semiconductor dice, eliminating the need for long electrical interconnects.
Co-packaging photonics with electronics can lead to signal integrity challenges. Minimising optical and electrical crosstalk to improve signal quality is essential. To do this, short interconnects, low-parasitic layouts can be used, as well as co-design tools for optical optimisation. Signal integrity can also be addressed without requiring more space or complex routing as optical interconnects can support multi-terabit-per-second data rates over long distances with minimal signal loss, expanding I/O capacity per chip considerably.
Thermal management and optical alignment Although optical components generate less heat than electrical interconnects, photonic devices, such as lasers and modulators, are sensitive to temperature changes. Careful thermal management and effective thermal design are required to maintain system reliability, as well as preventing performance issues and optical misalignment. Integrating photonics with electronics involves efficient thermoelectric coolers (TECs) and heat sinks, as well as smart thermal simulations during the design phase.
Optical misalignment can lead to significant insertion losses and drastically degrade device performance. Achieving sub- micron alignment is technically challenging. Implementing passive alignment techniques with etched features or alignment markers can be less accurate, but it is cost-effective. Active alignment, for example, using real-time optical feedback, results in better performance and efficiency, but it increases complexity and cost.
Testing and assembly
Despite the fact that testing optical components during and after packaging
can be complicated there are ways to deal with this, such as, built-in test waveguides, automated optical probing systems and standardized test procedures.
The integration of optical and electrical components into a single package increases the complexity of the manufacturing process, involving multiple assembly steps, which means higher costs and risks. Developing standardised processes for CPO assembly can help reduce complexity and improve yields.
Recent advances
As a result of the strong interest in photonic packaging there have been advances in this area. Sarcina Technology offers a wide range of photonic package solutions and design services that are ideally suited to companies focused on AI, HPC (high performance computing) and networking. The Sarcina team has expertise in semiconductor packaging, electrical engineering and photonics, and aims to ensure seamless integration and accelerated product development. Sarcina’s capabilities include CPO design, silicon photonics package integration, optical I/O and interposer design, mixed-signal and
photonic substrate design, custom optical connector and fibre attach, as well as thermal and mechanical co-design.
Going forward
Co-packaged optics (CPO) is a cutting- edge technology that integrates optical communication components directly into semiconductor chip packages. This approach enables faster data transmission and improved power-efficiency, overcoming the limitations of traditional copper-based interconnects. CPO has many advantages, including high-speed communication and lower power consumption, but there are also challenges related to signal integrity, thermal management, optical alignment and costs.
Advances in photonic package design can address these challenges and help electronic design engineers to create new architectures that would not be possible with traditional semiconductor packaging. It is widely acknowledged that photonic packaging will play a crucial role in the development of the next-generation HPC and AI systems.
https://sarcinatech.com/
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www.cieonline.co.uk Components in Electronics December/January 2026 35
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