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This Defense Intelligence Reference Document, DIA-08-1004-006, is dated 6 April 2010 and was prepared by the Defense Intelligence Agency's Defense Warning Office. It is one of a series of advanced technology reports produced in FY 2009 under the Advanced Aerospace Weapon System Applications Program. The report reviews electromagnetic and optical metamaterials and their uses in sub-diffraction imaging, component miniaturization, energy harvesting, optical isolators and tunable devices. It concludes that metamaterials remain academic but have great potential for aerospace applications.
From the source:Release of 2026-09-18 Incident: 4/6/10, 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 metamaterials, engineered structures designed to control electromagnetic waves in ways ordinary materials cannot, and argues that their main aerospace value lies in unusual optical and microwave properties together with significant component miniaturization. The report reviews possible applications including sub-wavelength imaging, compact waveguides and lasers, energy harvesting, tunable absorbers, nonreciprocal devices, and switchable materials, with particular emphasis on infrared and microwave uses for sensing, power management, and payload efficiency. It notes that many of the most ambitious applications depend on the practical output of a still-nascent field, especially in optical metamaterials, where only limited demonstrations had been achieved and fabrication remained a major constraint. The document presents metamaterials as a promising advanced materials field with credible niche applications and broader long-term potential.
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Specifically, it has been found that by making the mirror slightly leaky, we can actually
increase absorption. If the reflection coefficient of a mirror is given by r2 , then the
reflection/transmission coefficients r , t through the structure are given by:
(7)
where t2 = 1+ r2 and t0 = l + r0 • Note that Equation 7 turns into Equation 6 if
r2 = -1 (perfectly reflecting mirror). From Equation 7 it follows that it may be possible to
engineer the reflectivity 'i in such a way that minimizes reflection Ir 12 while keeping
transmission It 12 small. The remainder of the energy is guaranteed to be absorbed by
the quarter-wavelength th ick absorber.
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Figure 22. Preliminary Attempts to Design a Better Absorber Using Complementary MetaMaterials {U
shaped CMM). Note that only 40 percent absorptivity is possible with a smooth gold film . Paradoxically, this
absorptivity increases to 75 percent when the metal mirror is made "leaky" by perforating it with an array of CMMs
(left panel) .
The design process for engineering r1 using the simplest CMMs, U-shaped apertures,
has been started. Some of the preliminary results are shown in Figure 22. Figure 22
illustrates how the (relatively low) 40 percent absorptivity of the SiC film covered by a
smooth Au mirror (black line) can be boosted up to 75 percent by patterning the mirror
using CMMs. We call such a "leaky mirror" patterned by CMMs a MetaMirror. It is clear
from Figure 23 that a MetaMirror can be used for making absorptivity polarization
dependent (if that is desirable for applications demanding a reflector-polarizer).
MetaMirror can also be used for shifting the absorption wavelength which would be
highly desirable for developing broadband absorbers. We have found that there are two
mechanisms capable of making MetaMirrors: (a) excitation of the Long Range Surface
Plasmon Polaritons (LR-SPPs) on the patterned MetaMirror, and (b) excitation of highly
localized (shape-dependent but period-independent) SPPs. An example of the
mechanism (a) is shown in Figure 23, but we also have preliminary results indicating
that both mechanisms can be operational in the same MetaMirror for close-by
frequencies resulting in multiple dips of the reflectivity coefficient I r2 1- By comparing
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 38 pages are in the text index: search them above, or from the library's search.