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  • Volume 44, Issue 11

    • Volume 44, Issue 11

    More content from Volume 44, Issue 11

    Nanoimprint lithography (NIL) is challenging extreme-ultraviolet lithography for the 32 nm mode and beyond.
    Nov. 1, 2008
    FIGURE 1. The beam within the laser module of the nanoparticle tracking analysis system passes through a sample.
    The ability to see nanoparticles directly and individually allows a nanoparticle tracking analysis system to analyze samples with particles of varying sizes and shapes.
    Nov. 1, 2008
    (Courtesy of Polymer Optical Fiber Application Center, Nürnberg)
    FIGURE 1. A prototype POF liquid-level sensor (left) works by exploiting the refractive-index difference of light in air versus a liquid. The sensor consists of a bundle of fibers (lower right) illuminated by a red light-emitting diode (LED) and connected to a low-cost CCD camera. A computer measures the intensity per fiber and displays the liquid level as a bar (upper right).
    Polymer optical fiber is benefiting from new modulation techniques and polymer designs that are extending data rates to 100 Gbit/s and improving POF performance for sensors, data...
    Nov. 1, 2008
    (Courtesy of Fianium)
    FIGURE 1. A comparison of the visible spectral regions of new (upper spectrum) and conventional (lower spectrum) supercontinuum sources after dispersion through a prism demonstrates the extent of additional blue and UV spectral components achieved using the latest PCF developments.
    By changing the air-filling fraction of the photonic-crystal fibers used in white-light supercontinuum sources, the traditional “blue deficiency” of such sources is eliminated...
    Nov. 1, 2008
    FIGURE 1. Negative refraction bends light in the direction opposite from normal (positive) refraction. Energy flows in the same direction in a negative-index material as in one with a positive index, but light waves flow in the opposite direction, as shown at bottom.
    Fabrication of three-dimensional metamaterials with negative refractive index at optical wavelengths has opened the way to dramatic new types of optics, such as “superlenses.
    Nov. 1, 2008
    FIGURE 1. Ultraviolet (UV) detectors can be classified into several types, depending upon the mechanism of detection.
    Compared to ultraviolet detectors based on traditional semiconductors like silicon and gallium arsenide, nitride-based UV detectors have improved insensitivity to visible and ...
    Nov. 1, 2008
    FIGURE 1. Ellipsometric fitting of the experimental data (cross-hatched lines) and model (solid lines) is improved when a thin interface is included (right side) for a SIMOX structure.
    An advanced thin-film metrology tool based on spectroscopic ellipsometry and dedicated to the measurements of blank and patterned wafers is designed to reduce the need for modeling...
    Nov. 1, 2008
    (Courtesy of F. Hossain)
    FIGURE 1. Ab initio density functional theory determines the orbital isosurfaces for the nitrogen-vacancy center (left) and NE8 (right) center in diamond.
    Optically active color centers in diamond have been found to exhibit attractive optical properties that have paved the way to the realization of practical sources of single-photon...
    Nov. 1, 2008
    It makes sense that if the performance of a terahertz emitter is directly impacted by its surface structure (see “Black silicon emits terahertz radiation,” p.46)
    Nov. 1, 2008
    The three beams in the 2D-IR experiment include two IR (ωα and ωβ) and one visible (ωγ). The time delays of the ωβ IR pulse and visible pulse relative to the ωα IR pulse (top) are controlled by two delay stages (bottom). The lenses (L1 to L7) are all of calcium. The four-wave-mixing signal is detected by a photomultiplier after going through a series of filters (three short-pass filters at 770 nm and a 40-nm-bandwidth interference filter at 700 nm). [5]
    Biological scientists have often referred to proteomics, or the study of the proteome (a word coined in 1994 from protein and genome), as the next step after the gene sequencing...
    Nov. 1, 2008
    While red- and green-emitting phosphorescent organic light-emitting diodes (PHOLEDs) have made progress in the ten years since their discovery, blue PHOLEDs still are not efficient...
    Nov. 1, 2008
    Th 299840
    The hypothetical Maxwell’s demon opens and closes a tiny trapdoor dividing two containers of gas to shuttle atoms one way without exerting effort, raising the number of atoms ...
    Nov. 1, 2008
    Th 299304
    Supercollimation, the propagation of light without diffraction, uses the properties of photonic crystals to transmit signals over centimeter-scale distances—ideal for integrated...
    Nov. 1, 2008
    Single-photon sources have been successfully developed by coupling a single quantum dot (QD) to a photonic-crystal nanocavity.
    Nov. 1, 2008
    Th 299305
    Silicon (Si) nanowires are attractive as photodetectors for wavelengths ranging from ultraviolet (UV) to infrared because of their ability to trap carriers at the surface with...
    Nov. 1, 2008
    In a one-dimensional (1-D) periodic Bragg stack of light-emitting quantum wells (QWs), the standing-wave pattern has nodes at the QW positions, which for normal (perpendicular...
    Nov. 1, 2008
    Scientists at Discovery Semiconductors (Ewing, NJ), Science Applications International (Albuquerque, NM), the Air Force Research Laboratory (Kirtland AFB, NM), and Schafer (Albuquerque...
    Nov. 1, 2008
    FIGURE 1. A simple 4 × 4 single-wavelength router has certain switching states in which two data paths (red and blue) share the same physical path (purple cross)—rendering the two data streams unable to be separated.
    We should all look forward to the day when optical interconnects become an integral part of computer chips.
    Nov. 1, 2008
    FIGURE 1. A solid collimating TIR lens is designed using the surface of revolution of a Bézier curve.
    The rapid transition to light-emitting-diode (LED) light sources for applications across dozens of industries creates new challenges for optical engineers and the ray-tracing ...
    Nov. 1, 2008
    Th 299833
    In Jeff Hecht’s Photonic Frontiers, “Fiber to the home takes aim at a ‘100-megabit nation’ ”
    Nov. 1, 2008
    Th 302615
    Jaz, the world’s coolest modular measuring suite, is now available for multipoint sampling.
    Nov. 1, 2008
    (Courtesy of PowerPhotonic)
    Collimating optics are customized to each diode output in a laser-diode stack, correcting for aberrations as well as divergence.
    Without a doubt, the high-power diode-laser industry has seen leaps and bounds in the last decade in terms of raw power output.
    Nov. 1, 2008
    The OSA Foundation provides education grants to many of the Optical Society of America’s (OSA) student chapters and local sections.
    Nov. 1, 2008
    (Courtesy of Rensselaer Polytechnic Institute)
    A drop of water containing four parts per million of fluorescein dye, illuminated by laser light from the top, hangs in a near-perfect spherical shape (above), ideal for imaging. Images of a standard-resolution target taken with the oscillating liquid lens are in and out of focus through one complete period (below), from peak focus at t = 0.007 s (left), shifting out of focus at t = 0.020 s (center), and to the second peak of the next period at t = 0.033 s (right).
    Millimeter-size spheres of water driven back and forth like a harmonic oscillator can effectively capture high-quality video and images with much faster focusing than conventional...
    Nov. 1, 2008
    A metamorphic triple-junction solar-cell design (top) with an optimal radial wire vein design (inset) is the latest claim to record status in Europe. (Courtesy of the Fraunhofer Institute) The record efficiency of 40.8% was achieved at NREL with several layers of III-V materials in a triple junction (TJ) solar-cell design (bottom). (Courtesy of NREL)
    Scientists in the United States and Europe have independently announced records for solar-cell efficiencies, adding more mile markers on the road to low-cost solar energy.
    Nov. 1, 2008
    Nanosphere’s approach to direct detection of nucleic acid involves binding a gold nanosphere to the target sequence, and coating the nanoparticle with highly reflective silver that reflects LED light. The silver, which itself does not bind to the organics, serves as an evanescently illuminated marker.
    Nanosphere (Northbrook, IL) has developed a workstation that uses silver-coated gold nanoparticles to allow the simultaneous detection of multiple genetic targets with a single...
    Nov. 1, 2008
    Th Hybrid 01
    The world’s largest semiconductor company, Intel (Santa Clara, CA), is actively pursuing development of optical interconnects for use in and between computers.
    Nov. 1, 2008
    (Courtesy of Northwestern University)
    The cross section of a hybrid inverted green-emitting LED shows its ZnO top layer, its InGaN MQW active layer, and its GaN bottom layer. Only the bottom layer, which is deposited before anything else, requires fabrication at temperatures high enough to damage InGaN.
    While blue and red LEDs can be made to shine brilliantly and have a long life, high-brightness green LEDs tend to die early.
    Nov. 1, 2008
    An actual butterfly wing and a glass replica differ in reflectance by about 5% at most.
    A technique for making physically robust nanoscale optical components—precisely modeled on physiological structures of insects—has enabled researchers at Pennsylvania State University...
    Nov. 1, 2008
    FIGURE 1. When testing spherical optics, a null is easily achieved using standard reference optics (left). Testing an asphere in the same setup, however, results in a non-null test wavefront (center). The addition of auxiliary optics, which correct for the (nominal) aspheric portion of the test wavefront, produces a null (right).
    Null optics allow mild to strong aspheres to be interferometrically tested. As an alternative, subaperture-stitching interferometry measures mild to moderate aspheric surfaces...
    Nov. 1, 2008
    (Courtesy of the University of Kaiserslautern)
    Black silicon consists of needle-shaped structures created on the surface of silicon through high-energy irradiation or chemical treatment (top); the absorptive structure can have many applications, including being used as a source of terahertz radiation. The silicon was intentionally damaged (bottom) to confirm that the needle structure was indeed the cause of terahertz emission.
    Treating silicon with repeated high-energy laser pulses or through etching in a plasma creates nanosize structures on its surface, rendering the silicon black in color and able...
    Nov. 1, 2008
    (Courtesy of the University of Toronto)
    The wavelength spectrum of a Fourier-domain modelocking laser shows a sweeping range of 112.2 nm with a full-width-half-maximum value of 95.3 nm. The 62.6 kHz sweeping frequency will improve performance of OCT test instrumentation.
    Fourier-domain optical-coherence tomography (OCT) is now being widely used for biomedical imaging with a resolution of several micrometers.
    Nov. 1, 2008
    FIGURE 1. An example of a complex optical system shows multiple folds, wavelengths, and beam paths.
    Alignment of electro-optical devices with multiple paths, multiple sources, off-axis elements, tight tolerances, or difficult components can be simplified through well-known tools...
    Nov. 1, 2008
    (Courtesy of Avantes)
    FIGURE 1. The optical resolution of a spectrometer system is essentially the full-width half-maximum of the spectral peak(s) you want to acquire.
    When specifying a microspectrometer, the most important factors to consider for a given application include optical resolution, slit size, sensitivity, signal to noise, and grating...
    Sept. 9, 2008