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This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency's Defense Warning Office and dated 31 March 2010. It was produced under the Advanced Aerospace Weapon System Applications Program. It reviews chemical, solid-state, fiber, ultra-short pulse and free-electron lasers, as well as beam control, atmospheric propagation, DoD laser history and how spacecraft could be damaged by lasers. It projects that electrically powered lasers could enable MW-class weapons and spacecraft laser weapons within 20 years. It ends with shielding recommendations for spacecraft.
From the source: Release of 2026-09-18 Incident: 3/31/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys the development of high-energy laser weapons and notes that, although lasers had already become important military tools for ranging, guidance, and other lower-power uses, true weapon-class systems remained limited by power generation, beam control, atmospheric propagation, and logistics. The report reviews major laser types along with the optical, tracking, and thermal-management systems needed to make them militarily useful. It argues that high-energy lasers can offer important advantages over kinetic weapons in speed, precision, and low collateral damage, especially against softer or fast-moving targets, while also emphasizing that practical deployment has long been hindered by hazardous chemical fuels, thermal blooming in the atmosphere, power-supply constraints for mobile systems, and waste-heat removal.
UNCLASSIFIED/ fFOA OFFI€il.t.k YSE &P•tv FIBER LASERS Fiber lasers are also solid-state lasers but are frequently considered separately due their many differences in implementation. They are made of the same materials listed in Figure 4 and lase at the same wavelengths. A fiber laser can be visualized as a rod laser which has been stretched many meters with a resulting diameter about the size of a human hair. The fundamental reason is to improve heat dissipation. The ratio of a fiber's surface area to its volume is much greater than a rod or slab and the distance which heat must travel to the edge of the lasing medium is reduced by orders of magnitude . The lasing fiber is surrounded by a concentric, larger diameter undoped fiber into which pump light is injected (usually at the ends) and then allowed to leak into the lasing fiber along the entire length. Fiber lasers are manufactured or "pulled" in much the same way as conventional optical communications fibers. Because the fibers are so thin, the power which can be generated in any one lasing fiber before the onset of damage is currently quite limited. New approaches to injecting the pump light and controlling the laser beam as it is generated or amplified are occurring almost daily. Fibers have been constructed using multiple cores, photonic crystals and air spaces in order to increase the power of individual fiber lasers with good beam quality and in ways to combine the beams. The smallest diameter fiber lasers, which produce single mode beams with very good wavelength control and stable polarization, have demonstrated a few hundred watts and are currently thought to have a damage threshold upper bound of about 10 kW. Small numbers of these beams have been coherently combined using techniques which match wavelength, phase and polarization of each fiber laser in the cluster. The bandwidths of these laser/amplifier chains must be extremely narrow ( << 1 GHz) to maintain polarization and to then be coherently phased to about 01. ). rms. It remains to be seen how much total power can be generated with good beam quality and what are the fundamental limits to coherent combining. Phasing research into mechanical techniques which use deformable mirrors and passive approaches which use stimulated Raman scattering are both being aggressively pursued. These combining techniques, when applied to fiber lasers, are in their infancy and offer the potential for weapons with fairly long tactical ranges. Other single mode fiber lasers have been produced which generated as much as 5 kW. Although their outputs are of good beam quality, they lase over a wavelength band which is too broad to maintain polarization and cannot be coherently combined. However, these types of beams can be combined incoherently by individually focusing them onto the same spot (Figure 6), similar to incoherent combination of slab laser beams or by physically splicing the output fibers of the individual lasers onto a larger undoped fiber (Figure 7) which can accommodate the higher total power. UNCLASSIFIED/ fFOA QFFI&I.t.k YSE 8,.L\f 8
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 31 pages are in the text index: search them above, or from the library's search.