NATO exercise validates POLARIS with undetectable laser link between two Portuguese frigates.20 Oct, 2025
Naval News Navy 2025
Astrolight’s POLARIS laser terminals created a jam-resistant, spectrum-silent link between Portuguese Navy ships during REPMUS 2025 off Portugal, according to Seapower and a NATO DIANA note dated October 17, 2025. The result suggests a practical communications layer for radio-silent maneuvers and GPS-contested battles, with throughput suitable for multi-stream video.
A NATO sea trial has quietly shifted the comms playbook. During REPMUS 2025, Astrolight’s POLARIS free-space optical terminals linked NRP Dom Francisco de Almeida and NRP Dom Carlos I under rain, fog, and routine electromagnetic clutter, and the connection was not detected or jammed by participating ships, aircraft, drones, or shore sensors. NATO’s DIANA accelerator, which supports the Lithuanian start-up, published the same day that the link was radio-silent, unjammable, and undetectable, and that the team installed and operated the terminals at sea with Portuguese crews.
POLARIS is a compact, gimballed FSO terminal designed for large surface combatants and USVs. (Picture source: NATO/AIRO)What stands out with POLARIS is not the concept of free-space optical communication, already known to navies and space agencies, but its performance in fleet conditions. During the exercise, Astrolight’s team lived and worked on board with Portuguese crews to install and operate the terminals; the link was not detected by other ships, aircraft, drones, or shore sensors involved. DIANA highlighted the radio-silent, unjammable, and undetectable nature of this link in its program report.
POLARIS is a compact, gimballed FSO terminal designed for large surface combatants and USVs. The mass of about 16 kg eases mast integration and onboard maintenance. The link is horizon-limited, with a budget supporting up to 1 Gbps of useful throughput and aggregation of more than ten real-time HD video streams. The very narrow beam, 0.1° full angle, concentrates emitted energy up to 4 W and lowers the probability of interception while complicating jamming. Electrical demand remains around 200 W at 48 V DC, and integration is simplified by Ethernet interfaces for both data and control, which accelerates interoperability with naval IP networks and mission systems.
A related point from reports published over the same period: integration took place in particular on the modernized frigate Dom Francisco de Almeida; Astrolight indicated the use of multiple terminals per ship and emphasized that beam narrowness is the key protection against interception. A tight beam keeps energy on the intended path, reduces the chance that an opposing sensor enters the useful lobe, and prevents reconstruction of exploitable data. This is physics applied to naval C2: fewer stray photons, less to detect, less to disrupt.
A mature ship-to-ship laser link provides three immediate effects. It preserves emission control when commanders want ships to remain discreet while coordinating maneuvers, notably during screening, deception, or mine warfare tasks. It adds resilience in a fight with degraded GPS, where RF channels are saturated by jamming and decoys; while laser links do not solve navigation, they protect C2 paths that keep a group coherent. And because the link budget is directional and tight, electromagnetic spill is limited, which reduces cues available to targeting networks that now combine electronic warfare, passive sensors, and open-source collection. In practice, a frigate and a hydrographic vessel exchanging fused sonar plots, UxV telemetry, or video streams through an invisible conduit is the kind of discreet advantage that accumulates over time.
The horizon line remains a constraint: curvature and mast height cap range, though relays on UAVs or buoys can extend coverage. Weather attenuation is real, but the Portuguese trials, as well as earlier work with the Lithuanian Navy, showed usable throughput in rain and fog. Alignment and stabilization are non-trivial on moving decks; hence the need for gimballed platforms and reliable inertial references; here, multi-stream performance is a credible proxy for robust tracking in rough seas. Finally, lasers complement radio rather than replace it. In contested littorals, a mixed architecture that routes priority traffic over optics while keeping secondary data on encrypted radios remains the prudent approach.
The issue is to address vulnerabilities exposed by the current electronic warfare tempo in the Baltic and the North Atlantic, and later on the Arctic and Indo-Pacific routes. NATO navies observe persistent jamming that degrades navigation and communications; adding an optical layer that denies the adversary an easy intelligence cue complicates the strike chain and provides more decision time. The fact that a DIANA-supported company delivered an operational capability during a major Alliance exercise also matters for acquisition practices. It points to a pathway for rapid insertion of niche but critical subsystems that harden resilience without waiting for a new class of ship. If allies now move from demonstration to scaled deployment, naval groups could field, within a single budget cycle, an undetectable optical backbone for local C2 and uncrewed systems control, which is precisely what REPMUS was designed to enable.
https://www.armyrecognition.com/news/navy-news/2025/nato-exercise-validates-polaris-with-undetectable-laser-link-between-two-portuguese-frigates
