Defense Intelligence Reference Document Metamaterials For Aerospace Applications

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• Far Field Super-Lens Based on the Interferometry of Sub-Diffraction Waves.
Sub-diffraction imaging has long been considered to be possible only using near-
field microscopes. Those are fairly complex, slow-scanning, and large devices that
are not appropriate for advanced aerospace platforms. Metamaterials enable new
imaging modalities: super-lenses, hyper-lenses, and far-field super-lenses. In
addition to a survey of the existing scientific literature, novel ideas on developing a
new interferometric Far-field Super-Lens (FSL) based on the multi-beam multi-
detector technique utilizing materials with Indefinite Permitivity Tensor are
presented. Fabrication of such Indefinite Permittivity Materials (IPMs) for the mid-
infrared part of the spectrum is achieved and demonstrates the capabilities of
transmitting electromagnetic waves with the spatial period much smaller than the
vacuum wavelength of light. Interference between sub-diffraction waves enables
disentangling multiple diffractive orders and extracting their amplitudes.
• Nonlinear Non-Reciprocal Chiral Metamaterials: Developing Novel Optical
Isolators and "One-Way" Microwave Mirrors. These developments are
motivated by the need to construct one-way "light diodes" for compact optical
isolators. Presently there are two approaches to optical isolation: the most common
using magnetic fields, and the less developed based on using nonlinearities. A
different approach relies on the phenomenon of adiabatic mode conversion in
nonlinear chiral metamaterials. Preliminary theoretical results for a simple chiral
fiber with a variable twist period (pitch) that enables full transmission of a tightly
confined core mode in the forward direction and full mode-conversion of the core
mode into a cladding mode for the backwards propagation is obtained.
• Slowing Down Light and Miniaturizing Optical Components Using the
Phenomenon of Electromagnetically Induced Transparency in
Metamaterials. The speed of light places a natural limit on the size of
optical/microwave components. Metamaterials offer an exciting opportunity to slow
down light. This has two major implications: (a) light can be stored/manipulated in
smaller volumes, and (b) nonlinear effects are strongly enhanced by the resulting
energy compression.
Applications to Sub-Diffraction Imaging: Super-Lens and
Hyper-Lens
The super-lens is one of the earliest applications of metamaterials (Reference 21}, and
its principle is shown is Figure 5. Without the super-lens, all information about sub-
diffraction (or sub-wavelengths, which is equivalent) features of the periodic object
would have been lost. The reason for the information loss is evanescent decay of the
large spatial wavenumbers. The only method of accessing/measuring these features
would be to scan the object using a near field scanning optical microscope. By inserting
a super-lens between the object and the imaging plane1 evanescent waves may be
amplified and the image transferred forward. Unfortunately, this approach by itself does
not remove the need for a near-field scanning device~ the image that is recreated in the
imaging plane is still sub-wavelength, and needs to be read out.
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