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  • Volume 47, Issue 1

    • Volume 47, Issue 1

    FIGURE 1. There are two basic types of optical fiber sensors. Extrinsic devices (a) relay on a transducer, whereas intrinsic devices (b) do not.
    Fiber Optics

    MEDICAL APPLICATIONS OF FIBER-OPTICS: Optical fiber sees growth as medical sensors

    Jan. 1, 2011
    The intrinsic physical characteristics of optical fiber combined with its versatility in remote sensing make it an attractive technology for biomedical applications.
    (Courtesy of University of California–Merced)
    FIGURE 1. Optical energy spectra taken as a function of applied electric field reveal tunneling of a charge between two quantum dots (a). A slice (b) through the intense spectral line (red dash on left) is associated with the neutral quantum dot pair; two polarization components, πX and πY, can be distinguished [1,2].
    Positioning, Support & Accessories

    CHILLERS: Cryogenic cooling of optical systems takes many forms

    Jan. 1, 2011
    Pulse-tube and closed-cycle mechanical coolers can take optical systems down to temperatures where noise is low and performance is high.
    FIGURE 1. In comparison to a conventional SiPM, which has all electronics off-chip (top), a digital SiPM has cell electronics on-chip, including an ADC for each SiPM (bottom).
    Detectors & Imaging

    PHOTOMULTIPLIER TUBES: Silicon photomultiplier technology goes fully digital

    Jan. 1, 2011
    All-digital silicon photomultipliers contain ADCs and other electronics on-chip and can be made using a conventional CMOS process.
    FIGURE 1. In a spectrometer output, a ruler generated by precisely determined comb lines facilitates the exact measurement of frequencies in a wide spectral range.
    Research

    PHOTONICS APPLIED: FREQUENCY COMBS: Optical frequency combs forge precise optical clocks and more

    Dr. Rüdiger Paschotta
    Jan. 1, 2011
    Besides applications in metrology (most notably, optical clocks), highly stable optical frequency combs are playing a role in ultraprecise spectroscopy for astronomy and in other...
    (Courtesy of ICFO and ICREA)
    A cascaded multicrystal second-harmonic generation scheme (a) yields an optical-to-optical conversion efficiency of up to 56% when converting a 1064 nm ytterbium fiber-laser output to 532 nm green light. The efficiency values are compared for single-crystal (SC), double-crystal (DC), and multicrystal (MC) configurations for a range of fundamental power levels up to 30 W (b).
    Lasers & Sources

    SECOND-HARMONIC GENERATION: Multicrystal scheme yields 56% efficient SHG to green

    Gail Overton
    Jan. 1, 2011
    Due to the absence of suitable laser materials in the green wavelength range, second-harmonic generation (SHG) of near-infrared (IR) solid-state lasers near 1 μm has evolved as...

    More content from Volume 47, Issue 1

    (Courtesy of the University of Kaiserslautern)
    A metamaterial terahertz-radiation-focusing GRIN lens has 60 μm wide unit cells consisting of a 200 nm thick copper film sandwiched between two slabs of benzocyclobutene, a dielectric.
    Optics

    METAMATERIALS: Three-layer metamaterial lens focuses terahertz radiation

    John Wallace
    Jan. 1, 2011
    An optical metamaterial is made up of unit cells somewhat less than a wavelength in size.
    42699
    Research

    ANNUAL REVIEW AND FORECAST: Skies may be clearing, but fog still lingers

    Gail Overton
    Jan. 1, 2011
    Although laser industry sales recovered nicely across all sectors in 2010, the aftermath of the recession is still impairing visibility going forward.
    (All figures courtesy of Stefan A. Maier)
    FIGURE 1. Metallic nanoelements can be located relative to each other to accuracies as high as about 10 nm (a). Three stacked metallic bars form a nanostructure that absorbs but does not scatter light (b and c).
    Research

    PLASMONICS: Plasmonic nanostructures concentrate light

    Jan. 1, 2011
    Advances in plasmonic nanosystems enable manipulation of dark and bright modes, as well as concentration of light via transformation optics.
    (Courtesy of University of Illinois at Urbana-Champaign for all images)
    FIGURE 1. The width of the point-spread functions for interferometric synthetic aperture microscopy (ISAM) and optical coherence tomography (OCT) are shown as a function of distance from focus.
    Optics

    SOFTWARE & COMPUTING: Interferometric synthetic aperture microscopy eliminates OCT compromises

    P. Scott Carney
    Jan. 1, 2011
    Optical coherence tomography (OCT) emerged in the early 1990s as the marriage of broadband interferometry and scanning-light microscopy.
    (Courtesy of PARC)
    A miniature interrogation module that fits in a TO header (top) uses a position-sensitive detector and a linear variable filter to resolve tiny wavelength changes. In a vibration experiment (bottom), wavelength changes as small as 50 fm are detected.
    Detectors & Imaging

    FIBER-OPTIC-SENSORS: Miniature read-out sensor resolves wavelength changes to 50 fm

    Gail Overton
    Jan. 1, 2011
    Many optical sensors rely on the detection of small wavelength changes in response to changes in temperature, strain, adhesion of bioparticles, or change in the chemical environment...
    Lasers & Sources

    Deep-well structures in mid-IR QCLs improve efficiency

    John Wallace
    Jan. 1, 2011
    The active regions of quantum-cascade lasers (QCLs) are made of a superlattice of quantum wells (QWs) and barrier layers.
    (Courtesy of Edward Buckley)
    Using a defined measurement geometry for laser safety (top), the IEC 60825-1 standard calls out the testing parameters for meeting particular laser-safety classifications (bottom).
    Optics

    PICOPROJECTORS: Eye-safety analysis sheds light on scanned-beam picoprojectors

    Gail Overton
    Jan. 1, 2011
    Picoprojectors, with typical output values below 50 lumens (50 lm), are based on a number of different architectures.
    1101breaks Fig2
    Research

    Imaging sheds light on in-body movement of inhaled nanoparticles

    Gail Overton
    Jan. 1, 2011
    A collaborative effort from researchers at the Harvard School of Public Health, Beth Israel Deaconess Medical Center, Massachusetts Institute of Technology, and the German Research...
    (Courtesy of Ohio State University)
    Images of a Mach 10 airflow around a triangular 'trip' object are taken at a 500 kHz frame rate using PLIF with nitric oxide as the fluorescent agent (top). The field of view is 5 × 5 cm, and the light sheet is 1.9 mm above the object's surface. The tests were done in NASA Langley's Mach 10 wind tunnel (bottom).
    Research

    FLUORESCENCE IMAGING: Nitric oxide PLIF visualizes Mach 10 airflows

    John Wallace
    Jan. 1, 2011
    Hypersonic air and space vehicles include the Space Shuttle and the US Air Force X-37B, which both re-enter the atmosphere at Mach 25 before slowing to subsonic speeds.
    Figure1
    Research

    PHOTONIC FRONTIERS: THE EXTREME LIGHT INFRASTRUCTURE: The ELI aims to break down the vacuum

    Jeff Hecht
    Jan. 1, 2011
    Europe's ambitious program to develop short-pulse, high-intensity lasers begins work on three petawatt-class lasers this year. These lasers will point the way to plans for a 200...
    FIGURE 1. Electron micrographs of the cross-sections of the as-drawn and cleaved glass-clad crystalline semiconductor core optical fibers—silicon (a), germanium (b), and indium antimonide (c)—show the fibers possess a clean interface between the semiconductor core and the glass cladding.
    Fiber Optics

    OPTICAL MATERIALS: Semiconductor-core fiber promises novel nonlinear fiber-based devices

    Jan. 1, 2011
    Optical fiber with a semiconductor core has the potential to unify long, flexible, and robust fiber-based waveguides with the nonlinear, Raman, and infrared transparency of semiconducto...
    Research

    IN MY VIEW: Do we care who invented the computer?

    Jeffrey Bairstow
    Jan. 1, 2011
    The story of the man and his arch-rivals who claim to have invented the "computer" has just been revived-for the fourth or fifth time.
    Optics

    Double-negative-index metamaterials are proposed for the UV

    John Wallace
    Jan. 1, 2011
    Fabrication of negative-index metamaterial (NIM) lenses (which can image beyond the diffraction limit) has made progress, but the creation of such lenses for the visible spectrum...
    Optics

    New immersion-lithography technique halves polarizer period

    John Wallace
    Jan. 1, 2011
    Immersion lithography at ultraviolet (UV) wavelengths has been used extensively to create wire-grid polarizers consisting of parallel lines of aluminum or some other metal on ...
    (Courtesy of the University of Illinois at Urbana-Champaign)
    Two examples of NIVI images show the technique's capability for finding tumors and their boundaries. The pixelation in the images comes from undersampling, rather than the optical resolution of the system. The blue color-coded regions have been classified as normal, the red as abnormal (tumor), and the pink as indeterminate. An algorithm automatically computes a black-line boundary based on the NIVI data.
    Research

    CARS MICROSCOPY: NIVI quantitatively detects cancer cells

    John Wallace
    Jan. 1, 2011
    Diagnosing cancer in tissue biopsies has traditionally been done by experienced pathologists viewing a stained tissue sample under a microscope.