Free Space Optical (FSO) Communications in a Radio Frequency (RF) Denied Environment
Award last edited on: 5/1/2023

Sponsored Program
Awarding Agency
DOD : Navy
Total Award Amount
Award Phase
Solicitation Topic Code
Principal Investigator
William R Ziegler

Company Information

4S - Silversword Software and Services LLC

5520 Research Park Drive Suite 100
Catonsville, MD 21228
   (443) 693-7331
Location: Single
Congr. District: 07
County: Baltimore

Phase I

Contract Number: N68335-18-C-0586
Start Date: 6/5/2018    Completed: 12/12/2018
Phase I year
Phase I Amount
Operations of military aircraft within Anti-Access/Aerial Denial (A2/AD) or RF denied theaters of operation has become more challenging recently. In addition to manned aircraft, the proliferation of autonomous UAVs in defense applications requires advancement of communications capabilities over current technologies. Combining RF and optical communications interfaces offer distinct advantages over RF-only systems. A significant example is seamless communications and operations in RF denied arenas, providing a critical advantage over enemy forces whose communications are completely blocked.

TALOC is a low Size, Weight, and Power (SWaP) optical communications device that: Acquires and maintains a broad band communications link between two platforms in line of sight with one another Measures azimuth and elevation angle relative to each platform reference from one TALOC to another communicating TALOC and vice-versa Measures distance between communicating TALOC units Sees through atmospheric disturbances (clouds/fog) TALOCs preferably operate in the Near Infrared (NIR) at a wavelength that is eye safe, has low detectability, and low moisture absorption, enabling high transmission through clouds, fog, and high humidity areas.

Low Probability of Interception and Detection (LPI/LPD) Communication, Low Probability of Interception and Detection (LPI/LPD) Communication, RF Denied Communications, Free Space Optical (FSO), Laser Communications, high bandwidth optical, Anti-access/Area Denial (A2/AD), Near Infra-Red, No-RF Tactical , Communications

Phase II

Contract Number: N68335-20-C-0028
Start Date: 11/13/2019    Completed: 7/26/2023
Phase II year
Phase II Amount
4S Silversword Software and Services, LLC (4S) is developing a novel, robust, Free Space Optical (FSO) communications technology entitled Through the Air Link Optical Component (TALOC), applicable for use on military aircraft, both manned and unmanned. The basic concept involves three components, a tracking and acquisition system, a dedicated communications system, and a retroreflector array as shown in Figure 1-1. Operations involve scanning the horizon with a fan of light operating at 1620nm searching for a retro-reflection from another TALOC unit. Once a reflection of the scanning array is located, tracking begins by continued scanning around the spatial location of the acquired reflection. As soon as tracking is established, communications begins, utilizing a separate, dedicated, 1550nm light source. Tracking continues throughout the communications period to ensure a solid connection and reduce dropouts. TALOC uses no turret or gimbal to facilitate tracking and acquisition.

Beyond introduction of TALOC technology to the commercial arena, the proposed SBIR work breaks new ground in man-machine cooperation. In successfully demonstrating the FSO function, 4S will show that broad band communications creates an opportunity for expert systems to facilitate multi-platform cooperation and fuse information originating on coordinated platforms into actionable information and guidance to human operators. This innovative capacity will find commercial applications in such wide-ranging fields as hospital ambulance coordination, fire-fighting, border security, law enforcement, and security surrounding public gatherings.

F-18, Laser Communications, fso, NAVAIR, TALOC, RF denied, MQ-25, free space optical