Abstract
As chip-to-chip silicon photonics gain traction for their bandwidth and energy efficiency, collective communication has emerged as a critical bottleneck in scale-up systems. Programmable photonic interconnects offer a promising path forward: by dynamically reconfiguring the fabric, they can establish direct, high-bandwidth optical paths between communicating endpoints — synchronously and guided by the structure of collective operations (e.g., AllReduce). However, realizing this vision — when light bends to the collective will — requires navigating a fundamental trade-off between reconfiguration delay and the performance gains of adaptive topologies.
In this paper, we present a simple theoretical framework for adaptive photonic scale-up domains that makes this trade-off explicit and clarifies when reconfiguration is worthwhile. Along the way, we highlight a connection — not surprising but still powerful — between the Birkhoff–von Neumann (BvN) decomposition, maximum concurrent flow (a classic measure of network throughput), and the well-known α–βcost model for collectives. Finally, we outline a research agenda in algorithm design and systems integration that can build on this foundation.
Cite this work
BibTeX entry
@inproceedings{adaptivephotonicshotnets25,
author = {Addanki, Vamsi},
title = {When Light Bends to the Collective Will: A Theory and Vision for Adaptive Photonic Scale-up Domains},
year = {2025},
booktitle = {Proceedings of the 24th ACM Workshop on Hot Topics in Networks}
}