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Ultra-low Size Weight and Power-Cost (SWAP-c) Tactical Free Space Optical Communication System


TECHNOLOGY AREA(S): Info Systems, 

OBJECTIVE: Develop an ultra-low space, weight, and power-cost (SWaP-c) Free Space Optical (FSO) communications capability for individual solider tactical operations in contested radio frequency (RF) environments. 

DESCRIPTION: It has become imperative that the Army develop alternative capabilities to communicate with reduced electro-magnetic footprint, while assuring low probability to detect and low probability of incept (LPD/LPI) capability and supporting necessary bandwidth for modern battlefield operations. The Free-Space Optical (FSO) communication concept provides an alternative pathway for inherent LPD/LPI communications, while providing significant bandwidth and low electro-magnetic (radio frequency)emissions. One of the inhibiting factors preventing widespread use of traditional FSO communication systems based on macro-scale optics can be linked to their size, weight, complexity and overall cost per link. An ultra-low SWAP-c, FSO communication system could provide accessibility of this technology geared toward the Army need for ensured communication while on the move and at the lowest echelon. Challenges associated with accomplishing this goal are many-fold and will require modern-day automated photonics technology manufacturing to achieve the long-term goal of a low cost while overcoming specific issues associated with pointing-and-tracking (PAT), transmitter beam divergence, receiving aperture size limitations, and low signal detection at GHz-level speeds. Given these challenges is it envisioned that one of the few solutions would be derived from modern integrated photonics technology ARL is seeking a small business to demonstrate an ultra-compact FSO communication system. This demonstration should be capable of high bandwidth (Gb-level), low bit error rate (BER)(10-6), automatic PAT in an extremely compact form factor (< 100 cm3, 100s of grams, < 10 Watts of power consumption). There have been several rudimentary demonstrations of one necessary aspect for this program (e.g. wide-field of view beam steering) in a chip-scale form factor [1-2]. These systems might have the potential to address the SWAP-c requirements due to inherent size and long-term high volume fabrication pathway. Although these systems are interesting, none have demonstrated FSO communication functionality and there remains many impediments to embodiment of a full communication system that needs innovative and applied research and development to overcome. These ultra-compact FSO systems must overcome technical hurdles which the macro-scale system have done in past, including: aperture limits, low-signal detection at high data rate, full implementation of PAT with required field of view (FOV) and slew rates and finally low power consumption. 

PHASE I: Complete a conceptual system design for a ultra-low space, weight, and power-cost (SWAP-c), (< 100 cm3, 100s of grams, < 10 Watts of power consumption), Free-Space Optical (FSO) communication system with delineation of critical elements and associated risk poised to meet the Phase II and III goals. Detail the key design considerations and trade-offs associated with the approach including scalability for cost. Develop prototype plans for Phase II. Demonstrate proof-of-concept of core link technology including rudimentary beam steering and modulation functions. 

PHASE II: Demonstrate an initial prototype Free-Space Optical (FSO) communication system with data bandwidth of 1 Gbps, automatic pointing-and-tracking (PAT) function with 30 degree field of view (FOV) and maximum FOV slew time of 500 microseconds, bit error rate (BER) of 10-6 over 1-hour interval at 90% network capacity at an outdoor-range exceeding 200 meters in a modem form factor of 100 cm3 or less, weighing less than 400 grams and consuming 10 Watts or less power. Technology should be at the level of TRL 4/5 at the end of this phase with a dedicated plan toward fabrication scaling for reduced unit cost. 

PHASE III: Advance prototype Free-Space Optical (FSO) communication system to TRL 7/8 with data bandwidth of 2 Gbps, automatic pointing-and-tracking (PAT) function with 45 degree field of view (FOV) and maximum FOV slew time of 500 microseconds, BER of 10-6 over 1-hour interval at 90% network capacity at an outdoor-range 1000 meters in a modem form factor of 50 cm3 or less, weighing less than 200 grams and consuming 5 Watts or less. It is envisioned that this technology will enable near range dispersal of secure FSOC network for US tactical ground forces, which could also provide a dual-use commercial application pathway for local area networks in highly congested urban environments. Similarly a system of this type and capabilities would greatly reduce the cost of setting up urban Local Area Networks in developing areas. Applications of FSO communication system have direct pathway to transition through existing Army development investments currently underway for the alternative communication space. Finally, it is expected that the core of this technology will mature aspects of beam steering and integrated receivers, which could have direct dual-use in low SWAP-c laser ranging (LADAR) application for military and civilian use on autonomous platforms 


1: Chung et al.: Monolithically Integrated Large-scale Optical Phased Array in SOI CMOS, IEEE Journal of Solid-State Circuits, Vol. 53, No. 1, January 2018

KEYWORDS: Photonics, Free-Space Optical Communications - FSOC, Optical, Communications, Local Area Network - LAN, Network, Laser, Light, Free-Space 

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