Tech Briefs

Spatial Resolution and Contrast of a Focused Diffractive Plenoptic Camera

The concept of an imaging system that captures both spatial and spectral information has existed for a while. An example of one such imaging system that encodes both location and wavelength into an image is a Fourier Transform Spectrometer (FTS).

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Integrated Magneto-Optical Devices for On-Chip Photonic Systems

The magneto-optical (MO) oxide layer consists of (Bi,Y)3Fe5O12 or BiYIG, bismuth garnet. This material was selected because it has a better figure of merit than the CeYIG previously used, especially at lower wavelengths (1310 nm vs. 1550 nm). A top-down deposition process was developed in which BiYIG/YIG stacks are grown on the Si waveguide with YIG on top. The stack is annealed at 800°C/5 min to crystallize both layers, with the YIG templating the BiYIG leading to garnet phases rather than other oxides, and the BiYIG is directly on the Si waveguide. Initial attempts led to a film with Bi oxide phases, because the Bi was in excess and could not escape during the anneal as occurs in Si/YIG/BiYIG stacks. Hence the composition was adjusted to include slightly more Fe, which yielded films with only garnet peaks.

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Low Power Optical Phase Array Using Graphene on Silicon Photonics

Despite enormous advances in integrated photonics over the last decade, an efficient integrated phase delay remains to be demonstrated. This problem is fundamental – most monolithic thin film deposition relies on centro symmetric materials (such as silicon, silicon dioxide, silicon nitride), which by definition do not have an electro-optic effect. Such materials have been shown to be excellent transparent materials, however they are either optically passive, or rely on very small plasma dispersion effect or power-hungry thermo-optic effect for tunability. These phase change materials have losses associated due to heating or carrier injection in the waveguides. This research shows that graphene can be used to provide electro-optic properties to traditionally passive optical materials.

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Ultracompact, High-Speed Field-Effect Optical Modulators

The major goals of this research project included two parts. First, an ultracompact plasmonic electro-optical (EO) modulator was to be developed and investigated for efficient intensity modulation. Second, an ultracompact and high-speed EO modulator based on a dielectric platform was to be developed for straightforward integration with existing CMOS technology. Both modulators were targeted to facilitate next-generation interconnects for integrated photonic circuits.

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Inter-Laboratory Combat Helmet Blunt Impact Test Method Comparison

As the medical community learns more about brain injury, the importance of blunt impact mitigation becomes more apparent. As such, it is critical to make sure that research labs are not only capable of performing testing in this field, but also show inter-laboratory consistency and reproducibility. This study is a comparison between the two validated blunt impact testing labs (Aberdeen Test Center (ATC) and National Technical Systems (NTS) Chesapeake Testing Services (CTS)), and Natick Soldier Research Development and Engineering Center (NSRDEC).

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Hydraulic Testing of Polymer Matrix Composite 102mm Tube Section

The objective of this research was to hydraulically pressurize the internal diameter of one 102mm Polymer Matrix Composite (PMC) over-wrapped cylinder up to 25,000 pounds per square inch (psi) and during pressurization, in real time, collect and store pressure and strain data simultaneously. Strain data must be captured from the inside diameter of the oil filled metallic cylinder and from the outside diameter of the composite over-wrap material.

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Permeation Tests on Polypropylene Fiber Materials

The Toxic Industrial Chemical/Toxic Industrial Material (TIC/TIM) Task Force MFR#1 published in February 2009 focuses on inhalation hazards in an operational environment and provides a list of compounds prioritized based on toxic hazard and the likelihood of an encounter. With these types of vapor threats, cartridge-based air purifying respirators are used to protect the warfighter against chemical exposure. Traditional air purification materials often rely on porous carbons such as activated carbon or activated charcoal. Ongoing efforts seek to improve the performance of carbon materials in air purification applications as well as provide alternative materials.

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