Security by Light in Sensor Networks: A Structured Review of Optical and Photonic Security Mechanisms

Sensor networks increasingly combine exposed sensing nodes, optical communication, photonic hardware, near-sensor inference, and distributed infrastructure monitoring. This changes the security problem from protecting packets alone to establishing device provenance, measurement integrity, link confidentiality and availability, trustworthy inference, physical situational awareness, lifecycle control, and governance. This structured review with documented scoping searches examines security by light: mechanisms in which optical or photonic phenomena directly realize, constrain, compute, or observe a security-relevant function. The review synthesizes screened evidence across photonic roots of trust, visible-light communication and LiFi security, photonic intelligence, reservoir and chaotic photonics, and distributed photonic sensing infrastructure. Searches across arXiv, IEEE Xplore, ACM Digital Library, and Scopus yielded 228 deduplicated candidate records, of which 187 were retained as core evidence and eight as contextual evidence. To avoid overstating heterogeneous photonic work, retained records were separated into direct security evidence, security-adjacent capability evidence, background/framework evidence, and excluded records. The central result is architectural: light-enabled mechanisms are most defensible when they provide explicit, confidence-rated evidence to conventional security engineering. In this paper, confidence-rated evidence means evidence whose security interpretation is tied to a stated asset, adversary or failure mode, evidence role, validation setting, robustness limits, deployment fit, and reproducibility condition. This avoids treating optical novelty, spatial confinement, analog complexity, or high-dimensional dynamics as assurance by themselves. The paper develops an auditable taxonomy, evidence appraisal rubric, mechanism-family synthesis, integration architecture, maturity analysis, and research agenda for incorporating light-enabled mechanisms into secure sensor-networked systems.