Documents / Official release
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.
UNCLASSIFIED/ :£FQB OFEICI\k 1!18!! eNtf
sections, such as shown in Figures 15 and 16, will be primary candidates for
implementing optical and microwave non-reciprocity. Such metamaterials would be
comprised of a unit cell containing a non-radiative element (that is, a two-strip
capacitor-loaded antenna supporting a "dark" magnetic mode) and a single "bright"
dipole antenna. Such a system exhibits EIT when the frequencies of the "dark" and
"bright" resonances coincide. EIT results in energy compression and enhanced
non linearity. The source of the nonlinearity could be, for example, a va riable
capacitance diode (varactor) used as a capacitive load of the double-strip antenna. The
second (linear) mode could have an orthogonal polarization, and the coupl ing between
the two could be accomplished via spatially-period ic displacement of the single-strip
and double-strip antennas with respect to each other.
Tunable Switchable Metamaterials
Electromagnetic properties of most metamaterials are "hard-wired", meaning they are
determined during fabrication. That can be a serious impediment to using them in the
context of space exploration. Being able to change optical/electromagnetic properties of
a metamaterials-based device without having to re-manufacture it would be highly
desirable. Therefore, this survey is concluded by describing some of the recent progress
in making reconfigurable/switchable metamaterials. This is a new exciti ng area of
metamaterials research that is worth watching for applications. One of the first
electrically-controllable THz metamaterials has been reported in Reference 36, where
resonant properties of the electric split ring were controlled by applying reverse bias
between metal and highly-doped in GaAs layer. The schematic of the experiment is
shown in Figure 25. Without reverse bias there is no resonant response of the split ring
to incident THz pulse because highly-conductive electrons of the n-GaAs layer are
shorting the gap of the resonant split ring as schematically indicated in Figure 26(b).
With the applied reverse bias, electron density is depleted inside the gap. The resulting
transmission spectrum shows spectral dips which were converted into the effective
dielectric permittivity &eff (w) that exh ibited resonant peaks. The strongest of the peaks
corresponded to the Inductance-Capacitance (LC) resonance of the split ring. One
possible application of such electrically tunable metamaterial suggested in Reference 36
was a modulator. The authors claim that the performance of their device as a THz
modulator already exceeds current state-of-the-art electrical THz modulators (based on
semiconductor structures) by one order of magnitude on resonance. Moreover, their
device operates at room temperature. Needless to say, this metamaterial-based
modulator can be improved. For example, configurations exploiting EIT could result in
stronger modulation strength.
Another interesting possibility for tuning microwave metamaterials has been suggested
in Reference 37. Ferroelectrics (such as BST) can be tuned by applying DC voltage
which changes their dielectric permittivity. This property of BST was utilized to develop
frequency tunable magnetic metamaterials using metallic split rings loaded with
barium-strontium titanate thin fi lm capacitors. The resonant frequency of this medium
is voltage tunable across a 140 MHz band centered at 1. 75 GHz. The effective relative
permeability of the slab was shown to have Lorentzian shape that reaches minimum
values between -2 and -3 for biases from Oto 5 V. Therefore, permeability of the slab
can tune between positive and negative values, making it useful in applications
requiring a state switchable magnetic permeability.
UNCLASSIFIED/ {EAR OEEICl.t.ls: 1!181!! eNtf
30 Not linked to a story yet.
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.