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AAWSAP DIRD, Metamaterials for Aerospace Applications, April 2010

U.S. Department of War · 2010-04-06 · 38 pages · text from the file's own layer

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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A=l - cos0-.Jt:YY I A , -sin. 20/(μxxA z> (4)
cos0 + J£ YY Iμ,, - sin 2 0 l(μx.> l,μ"" = 1: A :=:d - tan4 (0/2), implying that A~ 0.97 even for 0 = n /6. The
challenge, if course, is to design a true impedance-matched optical metamaterial.
Success has been achieved in designing such a metamaterial (Reference 20).
The recently published design is shown in Figure 19. The unit cell consists of two layers
of plasmonic antennas; the cut-wire antenna that imparts magnetic (as well as some
electric) response to this metamaterial, and the continuous-wire antennas that impart a
purely electric response. It is found that the wide-angle capability could be very
important for several applications. Wide-angle power absorption efficiency is desirable
for miniaturizing photodetectors or microbolometers down to the wavelength size.
Continuous Silver
20nm
80
nm
I
I wires
control
μ eff
1450 1500 1550 1600 1650 1700
Wavelength [nm]
Figure 20. Specific Design of a Wide-Angle Plasmonic Absorber Based on Negative Index Metamaterial
Operating at A= 1550 nm. Left panel: Schematic of the silver-based plamonic structure. Right panel: Extracted
permittivity and permeability for the normal incidence demonstrate impedance matching: £ YY =μ ,, =-1 + i.
(Reference 20)
For example, to focus light on a wavelength-sized photodetector or micro-bolometer
requires high-NA optics (a NA=0.5 or higher). Therefore, a photodetector should be
able to absorb light incident at 30 degree angle. For advanced aerospace platforms it is
easy to envision a scenario where an airborne platform is powered by a high-power
infrared laser source located on Earth. If the wavelength falls inside the transparency
window of the atmosphere (between 3 and 4 μm, and also around 10 μm), then such a
22
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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.