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  • Volume 55, Issue 04

    • Volume 55, Issue 04

    (Adapted from http://bit.ly/2ulpehR)
    In a plot of transmission rate R as a function of spectral efficiency η (bits per second per hertz) and optical signal-to-noise ratio (Eb/N0), the channel capacity C is the Shannon limit. R cannot be greater than C.
    Fiber Optics

    Fiber-optic Communications: Fiber bandwidth pushes closer to nonlinear Shannon limit

    Jeff Hecht
    April 1, 2019
    News at OFC 2019 includes the transmission of 20 Tbit/s on each of eight fiber pairs, and experimental 6.21 bit/s-Hz for long-haul data efficiency.
    Research

    Small silicon-photonics-based optical scanner could work well for automotive lidar

    John Wallace
    April 1, 2019
    A nonmechanical chip-based optical scanner containing multiple optical switches and outcoupling gratings is small and rugged for lidar.
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    Lasers & Sources

    NIH licenses cancer-killing near-IR photoimmunotherapy to startup

    Gail Overton
    April 1, 2019
    Not only can targeted near-infrared light kill cancer, but it can facilitate the growth of healthy cells to replace cancerous cells, boosting the photoimmune response of the body...
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    Positioning, Support & Accessories

    Ultrafast laser drills 12,000 holes per second with 1 µm diameter

    John Wallace
    April 1, 2019
    Used with an ultrafast laser, a diffractive optical element generates more than 200 beamlets, allowing drilling of more than 12,000 holes per second.
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    Test & Measurement

    High-speed polarization camera has monolithic photonic-crystal sensor

    Gail Overton
    April 1, 2019
    A high-speed camera has a photonic-crystal polarizer with clusters of four 20 µm square pixels at four different polarizations to provide detailed polarization images.

    More content from Volume 55, Issue 04

    Content Dam Lfw Print Articles 2019 04 1904lfw Nb 1
    Detectors & Imaging

    Traditional cameras reach ultra-high imaging speeds with COSUP

    Gail Overton
    April 1, 2019
    Compressed optical-streaking ultra-high-speed photography (COSUP) uses a digital micromirror device (DMD) and a galvo scanner to reach millions of frames per second for standard...
    Conard 720
    Test & Measurement

    Business Forum: The wages of photonics: A salary survey

    Conard Holton
    April 1, 2019
    The ninth annual Optics & Photonics Global Salary Report from SPIE shows the continuing rise in income associated with jobs in photonics—along with a few surprises.
    FIGURE 1. For wallpaper samples with an identical pattern (a), the lamp in the image (b) acts as a fiducial to determine the correct orientation of the sample.
    Optics & Design

    3D Surface Metrology: Getting aligned with freeform optics metrology

    April 1, 2019
    Mechanical fiducials and precise 3D positioning can greatly simplify and improve the metrology tools needed to accommodate the introduction of deterministic surface generation...
    FIGURE 1. Shown at left is the fiber cross-section (top) and refractive index profile (bottom) for a feeding fiber with three guiding regions. Simulations (right) show the beam profile coupled into the guiding regions for different perturbation conditions. The beam homogenizes azimuthally as it propagates in the fiber.
    Lasers & Sources

    High-power Fiber Lasers: Fiber laser has all-fiber tunable beam quality

    Dahv Kliner
    April 1, 2019
    A newly developed fiber laser provides real-time tunability of beam characteristics directly from the laser output fiber using an all-fiber mechanism.
    Content Dam Lfw Print Articles 2019 04 1904lfw Nov 1 R
    Optics & Design

    Optical Design Software: Design for manufacturability in optical systems: In this case, perfection is the enemy

    April 1, 2019
    Techniques to reduce the impact of fabrication and assembly tolerances as part of the optimization process result in lower-cost optics for high-volume applications.
    FIGURE 1. Shown is an example of laser-induced damage on the surface of an optic imaged using differential interference contrast (DIC) microscopy.
    Spectroscopy

    Spectroscopy and Optics: Laser mirrors: High reflectance is measured best with cavity ring-down spectroscopy

    Ian Stevenson
    April 1, 2019
    For mirrors with reflectance values above 99.5%, measuring total loss through cavity ring-down spectroscopy is more accurate than conventional methods.
    FIGURE 1. A flow chart shows the basic process of image fusion in the spatial domain for a visible and infrared image of the same scene.
    Software

    Image Fusion: Spatial-domain filtering techniques dictate low-light visible and IR image-fusion performance

    Ayush Dogra
    April 1, 2019
    The performance of image-fusion algorithms depends heavily on how spatial information is extracted and processed through a variety of spatial-filtering techniques.
    FIGURE 1. A schematic side view shows an on-chip free-space section created using two waveguide-coupled GRIN lenses (a). The top view (b) shows two integrated GRIN lenses creating a free-space etalon (highlighted in yellow). The cross-section (c) illustrates a U-groove with integrated GRIN lens; the width and depth of the U-groove match the GRIN lens diameter of 125 µm.
    Detectors & Imaging

    Photonics Applied: Quantum Photonics: UNIQORN—Making quantum photonics affordable

    Moritz Kleinert
    April 1, 2019
    Blending on-chip ultrathin-film elements, nonlinear crystals, polymer interposers, and single-photon detectors, the UNIQORN project aims to develop a quantum system-on-chip methodology...
    Content Dam Lfw Print Articles 2019 04 Cover 2
    Home

    Clinical application of time-resolved fluorescence

    Barbara Gefvert
    April 1, 2019
    Label-free time-resolved (“lifetime”) fluorescence spectroscopy and imaging have demonstrated capability for multiple clinical applications, as evidenced by a new robotic surgery...
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    Research

    Medical lasers

    John Lewis
    April 1, 2019
    Editor in chief John Lewis discusses the Laser Market Review & Forecast report and invites you to enjoy Laser Focus World’s April 2019 issue, which includes trends in photonics...
    A laser-cooling crystal is mounted in a vacuum chamber for characterization. A continuous-wave optical parametric oscillator (CW-OPO) provides tunable coherent light, which is split by a beamsplitter to the crystal in the vacuum chamber and to an optical spectrum analyzer (OSA) to measure the OPO’s wavelength. A thermal camera monitors the temperature of the crystal.
    Positioning, Support & Accessories

    Laser Cooling: Thulium-doped fluoride crystals offer potential for mid-IR optical cryocooling

    John Wallace
    April 1, 2019
    Tm:YLF and Tm:BYF crystals are cooled by mid-IR laser light and can enable cryocoolers and radiation-balanced lasers (RBLs).
    Image credit: CREOL
    The emission spectrum (left column) and the far-field pattern (right column) are compared for a single laser cavity (a), a standard five-cavity laser array (c), and a supersymmetric (SUSY) array with a standard five-cavity array adjacent to a four-cavity superpartner lossy array (e). Similar to the single-element laser mode (b), the SUSY array emission (f) shows suppression of the higher-order modes seen in the standard array (d). Overall, the SUSY array has fundamental-mode operation with a smaller diffraction angle and higher quality factor than a standard laser array.
    Lasers & Sources

    Laser Arrays: Supersymmetry scales up radiance of coupled laser arrays

    Gail Overton
    April 1, 2019
    By placing a lossy superpartner array of waveguide cavities in proximity to a standard array, one can suppress unwanted higher-order transverse modes and amplify the fundamental...
    Mice who had retinal photoreceptor-binding upconversion nanoparticles (pbUCNPs, which anchor themselves to the inner and outer segments of both rods and cones) injected into their eyes showed pupil constriction when subjected to IR light at 980 nm, demonstrating that their eyes and brain had detected the IR light. In contrast, mice who had polyacrylic acid-coated upconversion nanoparticles (paaUCNPs, which did not anchor tightly to the rods and cones) injected into their eyes showed the normal visible-light pupil response, but no IR response.
    Research

    IR Upconversion Imaging: Upconversion nanoparticles in eyes enable mice to see infrared—may work for humans, too

    John Wallace
    April 1, 2019
    Injected ytterbium- and erbium-containing nanoparticles bind to rods and cones and convert 980 nm light to green light with a 535 nm peak.
    (Courtesy of the Mahadevan-Jansen Lab, Vanderbilt University)
    Parathyroid tissue (upper right) autofluoresces under near-IR light at significantly greater intensity than does any other tissue in the neck.
    Research

    Translational Research/Near-infrared Fluorescence: Intraoperative systems leverage parathyroid autofluorescence

    Barbara Gefvert
    April 1, 2019
    Detecting parathyroid tissue using near-IR laser light to induce autofluorescence can aid in distinguishing tissue in surgery.