Military applications of optical technology have a long history. For over 300 years, telescopes and binoculars have extended the range of a commander's vision. Periscopes allow submariners to view surface activities while submerged and, during World War II, the Norden bombsight provided American bombardiers accuracy that, although crude by today's standards, was unparalleled for its time. Since the invention of the laser in 1960 and the light emitting diode in 1965, advances in electronics have spilled over into optics and brought opto-electronics to the battlefield. Shortly after its invention, the laser was used to guide munitions in Vietnam. Night vision technology also made its first battlefield appearance in Vietnam. More sophisticated infrared imaging gave coalition forces in Operation Desert Storm a critical advantage in night operations. Advances in optics have enhanced air operations with cockpit head-up displays based on the principles of holography. Communication systems also continue to benefit from advances in optics. The term photonics derives from the photon, the elementary particle of light. In electronic systems, the electron carries information. In photonic systems, it is the photon. The term photonics is also used to distinguish between systems that use conventional optical elements to form images and those that use light to communicate, compute, and store information. One of the first applications of photonics to communications was the photophone, demonstrated by Alexander Graham Bell in 1880, which used light beams to transmit information wirelessly. Bell believed the invention of the photophone was more significant than that of the telephone, but it took almost a century for light to be used in communication; the first widespread deployment of optical fiber began in the 1970s. The recent downturn in the telecommunications industry was fueled in part by unmet expectations in the growth of optical fiber communications. However, the downturn was due to poor market predictions, not poor technology. The dependence of the GIG on optical fiber indicates strong support for photonics as an enabling technology for transformational communications. Although the application of optics to military communications is as ancient as warfare itself, the application of photonics is relatively more recent. Here we address the application of photonics to sensing and information processing for intelligence gathering, surveillance, and reconnaissance (ISR), in which the efficient generation and delivery of optically-encoded information is exploited. The outer shell of future military networks will be populated by sensors, and the Department of Defense (DOD) is pushing to provide sensor capabilities to tactical commanders. However, in tactical operations, bandwidths are reduced2 and operational urgency prevents data from being transmitted to ground stations for subsequent processing. To take full advantage of new capabilities, sensors must be able to collect data and rapidly extract from it and transmit actionable information. This can be accomplished if information is generated as close to the sensor platform as possible. However, tactical platforms, e.g., mini-unmanned aerial vehicles, place a premium on the size, weight, and power requirements of a sensor package. Other potential platforms include unattended ground sensors, unmanned ground vehicles, and even dismounted soldiers. It is in such applications, where the complexity of processing is high and the physical constraints on the system are limiting, that photonics offers the greatest advantage over electronics. The advantage lies in the fact that, whereas two electrons in close proximity affect one another, two photons do not. advantage over electronics in meeting this objective.
About the Author: Joseph N. Mait is a senior researcher at the US Army Research Laboratory. His research interests are in sensors and the application of optics and photonics to sensing and sensor signal processing. During the academic years 2001-2004 Dr. Mait was assigned to the Center for Technology and National Security Policy at the National Defense University where he researched topics related to Army transformation and technology. Michael W. Haney is a Professor of Electrical and Computer Engineering at the University of Delaware. His research is in the application of photonics to new computing, switching, signal processing, and image processing architectures. He was previously the Director of Photonics Programs at BDM International, Inc., as well as an Associate Professor of Electrical and Computer Engineering at George Mason University and co-founder of Applied Photonics. Keith W. Goossen has 17 years professional experience in the fields of optoelectronics and optical fiber communication. While at Bell Labs he invented and demonstrated several key components necessary for high-speed optical communications. In 2000 he co-founded Aralight, Inc. to commercialize this technology and guided engineering development to a full product demonstration two years later. In 2002 he joined the University of Delaware as an Associate Professor of Electrical and Computer Engineering to reengage in the pursuit of technology research. Marc P. Christensen is an Assistant Professor of Electrical Engineering at Southern Methodist University, where he researches information efficient sensor architectures and processing architectures that use photonic technology. His expertise is in hardware demonstrations of photonic technology gained through his industrial experience as technical leader in Sensors and Photonics at BDM International, Inc. and co-founder of Applied Photonics, Inc. in 1997. He joined Southern Methodist University in 2002.