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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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Definition of Metamaterials
A metamaterial is defined as an artificial medium whose properties (mechanical, optical,
magnetic, or other) cannot be found in naturally-occurring materials. The emphasis of
this study will be on electromagnetic and optical metamaterials. Such metamaterials
can exhibit rather extreme properties, such as negative refractive index, which implies
that both electric permittivity and magnetic permeability must be negative
( £ < 0 μ < 0) (Reference 1). Such meta materials used to be called " left-handed"
I
because of the unusual phase re lationship between the electric and magnetic fields.
Specifically, in most (positive index, including vacuum) media one uses the right-hand
rule to define the relationsh[p between electric field ( E) magnetic field ( H), and the
propagation wavenumber ( f ). The physical basis of the right-hand rule is that the
direction of energy propagation defined by the Poynting vector S= cEx HI 47Z' and the
direction of the phase velocity (defined by the wavenumber k) must coincide. That
does not hold true for negative index metamaterials where the two directions are
opposite, therefore, t he left-handed relationship must hold for the three vectors.
Nevertheless, the "left-handed" designation did not withstand the test of time because
it was causing confusion and creating irrelevant allusions to helica l (a.k.a. chiral)
structures. Although chiral structures can indeed exhibit negative index behavior
(Reference 2), chirality is not necessary.
A typical metamaterial consists of resonant elements such as Split Ring Resonators
(SRR). An example of an SRR is shown in Figure 1. The main function of the SRR is to
enable strong magnetic response of the structure. A simple empirical formula exists for
the magnetic permeability of a metamaterial comprised of the SRRs:
(1)
where {J)M is the resonant frequency of the SRR, and F is proportional to t he volume
filling factor of SRRs. It is noteworthy that SRRs are designed in such a way that it has
a large capacitance. As the result, the resonant freque ncy of an SRR is small, (that is,
the SRR-containing cell is very sub-wavelength). In the example shown in Figure 1
(taken from Reference 6), the unit cell operated at {J)j27Z" = 10 GHz is A/10. I n fact, the
sub-wavelength size of the meta material is what distinguishes them from their close
cousins: photonic crystals. By properly designing magnetic SRRs, it is possible to
achieve any value of μ for any given frequency. Special challenges exist for optical
structures, though, as will be explained below.
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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.