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    • Volume 47, Issue 9

    More content from Volume 47, Issue 9

    Conard Holton2
    Since its founding in 1958, the Defense Advanced Research Projects Agency (DARPA) has sponsored photonics research, from fundamental science to laser weapons.
    Sept. 1, 2011
    Researchers at the Max Planck Institute for the Science of Light (Erlangen, Germany) have developed the first soft-glass, hollow-core photonic-crystal fiber to offer singlemode...
    Sept. 1, 2011
    FIGURE 1. Radiation response as a function of absorbed dose is compared for three types of step-index multimode (SIMM) fiber cores: GeO2 and P2O5 co-doped (A); P2O5 doped (B); and GeO2 doped (C). The co-doped fiber core shows a simultaneous increase in sensitivity to dose and reduction in sensitivity to dose rate.
    A step-index multimode fiber co-doped with phosphorus and germanium is an excellent sensor for gamma-radiation doses; its low dependence on dose rate makes it potentially useful...
    Sept. 1, 2011
    FIGURE 1. Solar simulators come in a large variety of shapes and sizes, with varying capabilities. A large-area simulator (a) tests a commercial silicon PV module. The module is face down with voltage and current wires going toward the technician; the two metal pieces at each end correct for intensity variation during the flash. (Courtesy of Spire Solar) Many commercial solar simulators are much smaller in size (b). (Courtesy of Newport Oriel Instruments)
    Solar simulators—instruments that simulate the irradiance and spectral output of our own Sun in order to test photovoltaic solar cells in indoor environments—are not created equal...
    Sept. 1, 2011
    FIGURE 1. Small NIR plastic optics of PEI may be manufactured using the HRDT process.
    Understanding the plastic optics production process and the material requirements of the application enables customers to incorporate plastic optics into designs that lower costs...
    Sept. 1, 2011
    FIGURE 1. A schematic shows the layer structure of a pseudomorphic LED designed to emit at about 240 nm. The device structure includes an application-oriented nitride substrate (AONS), multiple quantum wells (QWs), and an electron-blocking layer (EBL).
    While progress is being made in the development of semiconductor UV lasers and LEDs, their external quantum efficiency remains low. One potential solution could be application...
    Sept. 1, 2011
    (Courtesy of Harvard University)
    A piezoelectrically (PZ) actuated scanning-fiber endoscope delivers pump/Stokes light for CARS and SRS microscopy in a spiral pattern to biological tissue through a special gradient-index (GRIN) objective lens (OL). An optical filter (OF) transmits the anti-Stokes wavelength to a photodiode (PD) for processing. The physical endoscope uses a 1 m section of fiber and the fiber scanner and objective lens are only 1.4 mm in diameter. Though the current system uses a 10 mm photodiode for light collection, simulations indicate that collection using a 5 mm or smaller detector will be possible.
    Both stimulated Raman scattering (SRS) and coherent anti-Stokes Raman scattering (CARS) microscopy use light from a pump and probe laser beam scanned over tissue or a test sample...
    Sept. 1, 2011
    A pair of split time lenses (STLs) in combination with a section of fiber having negative dispersion (-D) creates a time hole within which an event can occur undetected by the probe beam (top). Fiber with positive dispersion (+D) and a second pair of STLs close the time hole. Viewing the process in another way, the wavelength versus time of a single-wavelength source (a) is altered by STLs (b); a fiber time-compresses the altered sections (c) to create a time hole. A second fiber decompresses the altered sections (d), and finally another pair of STLs undoes the wavelength changes (e).
    "Temporal cloaking," a time analogue of invisibility cloaking, has been demonstrated optically by scientists at Cornell University (Ithaca, NY).
    Sept. 1, 2011
    (Courtesy of UCLA)
    An emissive polymer light-emitting device operating at 8 V undergoes strains of 0% (left), 20% (center), and 45% (right).
    The push to create wearable electronic devices is gaining steam.
    Sept. 1, 2011
    FIGURE 1. An image of interactive ray tracing for an infrared optical system shows the stray light paths.
    Infrared (IR) surveillance systems are used in satellites that survey the earth's surface to carry out environmental analysis—for example, to monitor marine pollution or study...
    Sept. 1, 2011
    FIGURE 1. A test setup is shown for ensquared/encircled energy (EE) testing.
    The often overlooked ensquared and encircled energy (EE) test method-a quantification of the fraction of optical energy present in an aperture for an optics system-can provide...
    Sept. 1, 2011
    One of the many rewards of a lengthy career in journalism is the opportunity of meeting unusually talented people and interviewing them for publication to a wide audience.
    Sept. 1, 2011
    1304qa Chang New
    I don't feel I am adequately compensated for the work I do. How is compensation determined, anyway?
    Sept. 1, 2011
    (Courtesy of Sigma Space Corp.)
    The single-photon lidar system provides an oblique view (top) and a side-view image (bottom) of the biomass distribution in the New Jersey Pine Barrens, including a fire tower surrounded by a chain-link fence. An independent ground-based hypsometer measurement of the tower height at 33.3 + 0.3 m was in good agreement with the 33.2 m height determined by the lidar.
    Compared to conventional waveform-digitizing altimeters or laser time-of-flight lidar techniques, photon-counting lidar is a more efficient technique as it requires only one detected...
    Sept. 1, 2011
    (Courtesy of GE Global Research)
    A prototype optical holographic drive system records data onto a volume-holographic disc capable of holding 500 Gbytes of data.
    Researchers at GE Global Research (Niskayuna, NY) have made progress toward their goal of creating a practical 500 Gbyte CD-sized disc based on holographic technology.
    Sept. 1, 2011
    Two distributed Bragg reflectors (DBRs) define the cavity of a blue- or green-emitting room-temperature electrically pumped GaN-based VCSEL. The active region consists of five multiple quantum wells (MQWs); a layer of silicon dioxide (SiO2) and conductive indium tin oxide (ITO) define the current aperture.
    Scientists at Nichia Corp. (Anan, Japan) have demonstrated the first electrically pumped indium gallium nitride/gallium nitride (InGaN/GaN)-based blue- and green-emitting vertical...
    Sept. 1, 2011
    (Courtesy of III-N Technology)
    A grayscale projected image of penguins from a green InGaN microdisplay (having a pixel size of 12 µm, pitch distance of 15 µm, and 19,200 total pixels) operates at a driving current of 1 µA per pixel. The device consists of an InGaN quantum-well active layer embedded between n- and p-type GaN. The InGaN quantum well has an emission wavelength of 517 nm.
    Not only is its luminance level several orders of magnitude higher than liquid-crystal-device and organic light-emitting diode displays, but a new video-capable emissive indium...
    Sept. 1, 2011
    FIGURE 1. Time-resolved laser-induced-breakdown spectroscopy (LIBS) study of a copper alloy uses an iStar ICCD camera and Shamrock 303 spectrograph.
    The latest generation of research-grade imaging and spectroscopy ICCD cameras uses novel software-customizable approaches to signal readout management and intensifier gating, ...
    Sept. 1, 2011
    (Courtesy of DARPA)
    FIGURE 1. Phased array of laser emitters mounted on the surface of an aircraft would generate and steer a combined beam. The two views show the surface and a cutaway view.
    High-risk, high-payoff research is DARPA's charter. The agency tackles a wide range of photonics challenges, including building high-energy lasers compact enough to get off the...
    Sept. 1, 2011