Jointly packaged optics

The spread of services such as Generative AI and cloud computing is forcing data centers to support higher speeds and greater capacities, such that power consumption continues to rise. Some estimates suggest that, at the current pace, power consumption of data centers will account for about 10% of total power consumption in 2030. Therefore, data center power saving (greening) has become an urgent issue. Photonic-Electronic Convergence technology is expected to be one solution to this challenge. By integrating optoelectronics into electronic devices and replacing electrical wiring with photonic wiring, the technology aims to increase network capacity and lower latency, and to significantly reduce the power consumption of all the systems in a network.

Development Steps of Co-packaged Optics

The convergence of circuits that handle electrical and optical signals is called photonics-electrics convergence, and several generations, such as LPO, CPO, and NPO*1, are currently in research and development stage. The first generation is the “optical module type” with miniaturized optical transceivers (optical engines) mounted near a logic chip, such as an ASIC, to form a module. The next generation is the "high-performance semiconductor package type" using chiplets*2.

 

*1: LPO: linear drive pluggable optics, CPO: co-packaged optics, NPO: near-packaged optics
*2: chiplet: A small bare chip (die) manufactured for a specific function using optimal process.

Challenges

The heat generated by laser diodes limits the optical output power and degrades signal waveforms. Therefore, in co-packaged optics development, it is necessary to evaluate the physical characteristics of the optical waveguide, such as the loss and polarization characteristics, using actual signals.

Solutions

The performance of a photonics-electronics convergence device is evaluated according to the following:
Frequency characteristics:
Check that the optical receivers, optical transmitters, and electrical signal transmission lines provide sufficient bandwidth.
Signal waveform quality:
Check the electrical signal waveforms in the package and the effects of noise.
Bit error rate:
Checks to how many symbol errors are corrected by the error correction process.