Mission Assurance at the Optical Layer: OT Zero Trust with Photonics

(Created by author using gen AI)

No Single Approach to Security

There is never a one-size-fits-all solution to zero trust. In fact, the United States General Services Administration (GSA) states this directly: “There is no single technology, product, or service that can achieve the goals of implementing a ZTA.” Therefore, we need to start with what already works in OT security:

• Zones and conduits
• Deterministic behavior and outcomes
• Safety and availability as first-order requirements
• Explicit boundaries between OT and enterprise
• Visibility that does not create outages
• Recovery that is not improvised

But where can photonics strengthen those fundamentals in a way that maps to OT zero trust outcomes? Photonics can make segmentation easier to sustain, increase monitoring confidence and enable more intentional connectivity patterns for the pathways that create the most risk in OT. The OT zero trust conversation has matured quickly. A year ago, many teams were still debating whether OT belonged in zero trust execution at all. That debate is fading, replaced by better engineering questions:

• How do we segment without creating fragility?
• How do we monitor without causing outages?
• How do we control OT to enterprise pathways without starving telemetry?
• How do we make remote access explicit and time-bound?
• How do we incorporate physical realities into assurance?

Photonics are showing up more often because it can help answer those questions with OT-friendly tradeoffs. It enables stable segmentation backbones, stronger link truth signals, and more intentional connectivity patterns for the riskiest pathways.

Defining OT Photonics Deployment Models

Photonics for ZTA can be structured into two separate models that map to OT zero trust outcomes.

Model 1: Optical Backbone for Durable Segmentation

This model uses photonics primarily as the transport substrate for zones and conduits. The goal is to make segmentation sustainable. What it looks like:

• Fiber-first inter-zone connectivity
• Backbone headroom that prevents segmentation from becoming a bottleneck
• Reduced susceptibility to electromagnetic noise in harsh environments
• Clear separation between real-time control pathways and analytics pathways

Segmentation requires operations to be running efficiently and correctly. When links are unreliable or constrained, teams create bypasses. When backbones are stable and have capacity, teams keep the design intact. This model is the best starting point when the dominant risk is lateral movement enabled by overly flat OT networks or fragile segmentation.

Model 2: Optical Switching and Controlled Connectivity

This model uses photonics to change how connectivity is granted. The goal is to make “default deny” meaningful at the pathway level. In OT, the most dangerous connectivity is often not a clever exploit. It is a permanent pathway that exists because it is convenient, such as vendor access that never turns off, engineering workstation reachability that expands over time, OT-to-enterprise flows that started as a one-time integration and becomes permanent. Controlled connectivity patterns aim to fix that by making pathways intentional events:

• Created when needed
• Limited in scope
• Time-bound
• Auditable

For example, Optical Circuit Switch (OCS) physically disconnects a path when not in use. This “air-gap on demand” is a unique photonic capability that standard Ethernet switching cannot replicate as securely.

Compliance Engineering and a Self-Healing Environment

OT security programs become insufficient when assurance becomes spreadsheet-only governance. OT security governance and assurance must exist as a byproduct of operations. Photonics supports that shift in three practical ways. 1. Link truth becomes a security signal Optical infrastructure provides health and integrity telemetry. Treated correctly, it helps reduce ambiguity during incidents:

• Degradation trends that suggest physical disturbance
• Error-rate changes that correlate with traffic anomalies
• Link instability that does not align with maintenance windows

Reducing ambiguity reduces downtime and reducing downtime means everything in OT. 2. Segmentation drift becomes detectable Barring a few dramatic examples such as Stuxnet, OT segmentation rarely fails catastrophically. It fails quietly: a bypass cable, a convenience Virtual Local Area Network (VLAN), a tunnel left open. Over time, the system drifts away from the design baseline. A mature posture continuously validates segmentation intent. Photonics do not do that alone, but stable optical backbones and optical-layer signals make drift easier to detect and faster to troubleshoot. The result is fewer “mystery” outages and fewer silent architectural regressions. 3. Pathways can be governed as intentional events The riskiest OT connections are the ones that exist permanently “just in case.” Controlled connectivity patterns encourage a different posture: create access only when needed, prove it, log it, and remove it when done. This aligns with zero trust intent in a way OT can adopt: reduce ambient access without breaking operational workflows.

Photonics Industry Advancements

Two American companies are leading the way in innovative photonic designs to support ZTA. Coherent Corporation and Lumentum Holdings are two of the best-known U.S. photonics companies, sitting at different but complementary layers of the optical stack. Coherent is a diversified photonics manufacturer with major businesses in lasers and materials processing, plus a large and growing footprint in datacom optics and optical components used in high-speed networks. They play across “industrial photonics” and “network photonics,” which makes them a useful reference point for how optical technology migrates from specialized applications into scalable infrastructure. Some of the latest designs highlighting zero trust capabilities include: OCS: Coherent positions a large port-count optical circuit switch, described as a 300×300 platform built on its digital liquid-crystal technology. (Courtesy Coherent Optical Circuit Switch) https://www.coherent.com/news/press-releases/optical-circuit-switch-for-data-centers-live-demo-at-ofc-2024-based-on-ultrareliable-dlx-technology