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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 6 April 2010, reviews electromagnetic and optical metamaterials for aerospace use. It was produced in FY 2009 under the Advanced Aerospace Weapon System Applications (AAWSA) Program. The report covers super-lenses and hyper-lenses for imaging objects smaller than the diffraction limit, slowing light to shrink components, energy-harvesting absorbers, and one-way chiral devices. It concludes that metamaterials matter for aerospace because they allow smaller, lighter components.
UNCLASSIFIED/;FF&R 8FP1@!1fct lt!ll!! CHE I (4) where we've assumed that, for normal incidence, this metamaterial is impedance- matched: e11 = J.l;: =-I+ i, Equation 4 can be simplified under the assumption off&,_1f >> l,Jt,x =I: A~ 1- tan 4 (0/2), implying that A""' 0.97 even for O = 1l /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. 20 Inm 80 1nm Continuous Silver Wires Control &ett wires control μen 4 3- 2· 1 0•••• -2 Impedance Matching .. ~ . 'I ....I ...t ', I ... -Rer ''" iflH -3 •••Re fl lm.11 1~50 1500 1550 1600 1650 1700 Wavelengt11 [nrnj Figure 20. Specific Design of a Wide-Angle Plasmonic Absorber Based on Negative Index Metamaterial Operating at A=lSS0 nm. Left panel: Schematic of the silver-based plamonic structure. Right panel: Extracted permittivity and permeability for the normal incrdence demonstrate Impedance matching: e_,:,- = f.J::.::. = -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 UNCLASSIFIED//fi8fl 8Pfllll!l,icl!: U81! 8HLY
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 27 pages are in the text index: search them above, or from the library's search.