State of the Art and Evolution of High-Energy Laser Weapons

This Defense Intelligence Reference Document, dated 31 March 2010, provides a comprehensive technical assessment of the state of the art and evolution of high-energy laser (HEL) weapons. The report was produced under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It begins by distinguishing between kinetic energy (KE) weapons and HEL weapons, noting that while KE weapons rely on physical impact, HEL weapons deliver energy at the speed of light, offering precision and efficiency against specific targets. The document traces the history of laser research from the initial theoretical work by Basov and Prokhorov in 1952 and the first working laser by Theodore Maiman in 1960, through the Department of Defense's subsequent investment in high-average-power systems.

The report categorizes laser technologies into several types: chemical lasers, which were the first to achieve megawatt-class power but are hampered by the need for hazardous chemicals; solid-state lasers, which are attractive for their portability and use of electricity; fiber lasers, which offer ruggedness and potential for scaling; ultra-short pulse lasers, which are currently in their infancy for military application; and free-electron lasers (FELs), which are unique in their ability to produce beams at various wavelengths. A significant portion of the document is dedicated to the challenges of beam control and atmospheric propagation, explaining how molecular constituents and turbulence in the atmosphere can degrade laser performance. The report also addresses the vulnerability of spacecraft to laser radiation, highlighting the risks to solar panels, sensors, and structural integrity.

Looking toward the future, the document suggests that the focus of laser development will remain on electrically powered systems, specifically solid-state and free-electron lasers, as they avoid the logistical burdens of chemical fuels and offer better propagation characteristics. The report concludes with recommendations for protecting spacecraft against potential laser threats, such as using baffled telescopes, reflective coatings, and shielded cabling. It also provides a list of professional societies and conferences relevant to the field, such as the Directed Energy Professional Society (DEPS).