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Self-Healing Wire Insulation
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Space Optical Communications Using Laser Beams
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Compact Packaging of Photonic Millimeter-Wave Receiver

Bulky positioning mechanisms are not needed A carrier structure made from a single silicon substrate is the basis of a compact, lightweight, relatively inexpensive package that holds the main optical/electronic coupling components of a photonic millimeter- wave receiver based on a lithium niobate resonator disk. The design of the package is simple and provides for precise relative placement of optical components, eliminating the need for complex, bulky positioning mechanisms like those commonly used to align optical components to optimize focus and coupling. Although a prototype of the package was fabricated as a discrete unit, the design is amenable to integration of the package into a larger photonic and/or electronic receiver system.

Posted in: Briefs, TSP, Physical Sciences

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Fabrication of Submillimeter Axisymmetric Optical Components

Surfaces of components can be arbitrarily shaped to optimize spectral responses. It is now possible to fashion transparent crystalline materials into axisymmetric optical components having diameters ranging from hundreds down to tens of micrometers, whereas previously, the smallest attainable diameter was 500 m. A major step in the fabrication process that makes this possible can be characterized as diamond turning or computer numerically controlled machining on an ultrahigh-precision lathe. This process affords the flexibility to make arbitrary axisymmetric shapes that have various degrees of complexity: examples include a flat disk or a torus supported by a cylinder (see figure), or multiple closely axially spaced disks or tori supported by a cylinder. Such optical components are intended mainly for use as whispering-gallery- mode optical resonators in diverse actual and potential applications, including wavelength filtering, modulation, photonic generation and detection of microwaves, and research in quantum electrodynamics and quantum optics.

Posted in: Briefs, TSP, Manufacturing & Prototyping

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Wide-Band, High-Quantum-Efficiency Photodetector

This device could detect single photons. A design has been proposed for a photodetector that would exhibit a high quantum efficiency (as much as 90 percent) over a wide wavelength band, which would typically be centered at a wavelength of 1.55 μm. This and similar photodetectors would afford a capability for detecting single photons — a capability that is needed for research in quantum optics as well as for the practical development of secure optical communication systems for distribution of quantum cryptographic keys.

Posted in: Briefs, TSP, Physical Sciences

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Diffractive Combiner of Single-Mode Pump Laser-Diode Beams

Multiple beams can be combined without inducing multifrequency lasing. An optical beam combiner now under development would make it possible to use the outputs of multiple single-mode laser diodes to pump a neodymium: yttrium aluminum garnet (Nd:YAG) non-planar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, an Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained below, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency.

Posted in: Briefs, TSP, Physical Sciences

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Distributed Control Standard Connects Industry Regardless of Bus

In the early days of modern automation, the use of microprocessor technology addressed the need for fast and efficient configuration of control logics through graphical methods that mimic the hardwired relay logics. Over the past 30 years, the automation community has put the emphasis on simplifying and standardizing the method of programming this new breed of controllers. From these efforts came the adoption of the IEC 61131-3 standard that specifies the programming languages for automation.

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Bringing Modularity to MicroTCA

MicroTCA is a new specification that offers very high performance packed in a small form factor. The new specification is expected to be used in a wide variety of applications, including mil/aero, telecom edge, medical, enterprise and data, and scientific applications. However, there are so many possible configurations, it can be overwhelming. How can one develop various systems and offerings without starting from scratch — and the time to market, high costs, and implementation issues this brings? One solution is using modularity in MicroTCA designs. Prototyping and development of a new system enclosure design can be a time-consuming and costly process. Building upon a proven modular platform allows a wide range of design options with significantly reduced effort.

Posted in: Articles, Articles

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Filtered Conduction Empowers Mil-Spec Desert Systems

As embedded computing systems become more powerful, so are the challenges to protect and cool the payload. In the past few years, we have seen the power of a single board increase in most cases to over 100W per slot. To further challenge the designers, these systems are being deployed in rugged environments with a push to use COTS (commercial off-the-shelf) products. Recently, liquid-cooled systems have been developed to combat these However, there are some challenges with liquid cooling that can make this technology prohibitive. For example, not all boards are available in conduction- cooled format, or there may not be an external chiller/pump available to implement the liquid approach. So how does a designer handle an environment where there is no liquid coolant available, ambient temperatures hover around 55°C, the enclosure has a payload of 500W, and the client wants the system to operate on numerous rugged platforms (ground vehicle, rotary wing, UAV, etc.)? Oh, and the enclosure has to be sealed to protect the COTS boards from the harsh environments and EMI concerns. And with all of this, there is a desire to monitor the temperatures/ health of the system to protect the expensive payloads.

Posted in: Articles, Articles

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