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  • Volume 45, Issue 3

    • Volume 45, Issue 3

    (Courtesy of Sun Microsystems)
    FIGURE 1. A two-dimensional (2-D) microchip uses proximity couplers to optically link processor, memory, and other chips in a grid array (top). Fabrication of all-optical on-chip structures allows photonic connection via replaceable optical proximity couplers between chips for “speed-of-light” connectivity (below), allowing the 2-D microchip to function as efficiently and as fast as if it were a single monolithic chip.
    Research

    PHOTONICS APPLIED: INTEGRATED PHOTONICS: Can optical integration solve the computational bottleneck?

    Gail Overton
    March 1, 2009
    An ambitious DARPA award to Sun Microsystems and its partners to develop a chip-to-chip and intrachip communications platform offers a glimpse into the world of next-generation...
    Th Lfw Prod Gamma
    Optics

    New products

    March 1, 2009
    Digital light source RS-5-93K characterizes the performance of image sensors and image-sensor systems.
    Research

    Let poor old Galileo rest in peace

    Jeffrey Bairstow
    March 1, 2009
    For the staggering sum of around $400,000, a group of contemporary body-snatchers is planning to open Galileo’s tomb in the Basilica of Santa Croce in Florence.
    Research

    Lasers break new ground

    Stephen G. Anderson
    March 1, 2009
    There have been some remarkable developments in a number of laser technologies recently–something for everyone, in fact!
    Th 311906
    Detectors & Imaging

    Manufacturers’ Product Showcase

    March 1, 2009
    The new 48-page catalog from Fermionics Opto-Technology contains specs, drawings, and photos describing InGaAs photodiodes for communications, monitoring, instrumentation, and...

    More content from Volume 45, Issue 3

    (Photo by Dan Leafblad)
    In a setup designed to test a space-elevator power-transmitting optical system, light from an LED on a distant tripod reflects off a mirror (left, facing away) to an image sensor (right). The resulting image data is processed to provide a signal that drives the mirror actuators, which in operation will keep the power-transmitting laser beam aligned to its target. In this test, the LED is moved farther down the road in the background out to 1 km to test system performance.
    Research

    OPTICAL POWER TRANSMISSION: Light-powered elevators race to the sky

    John Wallace
    March 1, 2009
    If ever implemented, the proposed Space Elevator–a vehicle able to travel up and down a super-strong cable extending from Earth to geosynchronous orbit and beyond–would drastically...
    (Courtesy of the University of Texas at Austin)
    A pulse-compression chamber uses 40 × 80 cm diffraction gratings to compress the laser pulse from a few nanoseconds to 167 fs. The diffraction gratings are some of the largest in the world.
    Research

    CHIRPED-PULSE AMPLIFICATION: Petawatt now, exawatt on the horizon

    John Wallace
    March 1, 2009
    Completed in early 2008 at the University of Texas at Austin, the Texas Petawatt is a 200 J, 150 fs, mixed-glass, optical-parametric chirped-pulse-amplifier (OPCPA) laser that...
    (Courtesy of Technion-Israel Institute of Technology)
    For a hazy image with objects as far away as 34 km (above, left; red circles mark buildings, green rectangles show arbitrary points at different distances), polarization and scattering effects can be removed and the image can be de-hazed (above, right) when a portion of the sky is visible. But in a “skyless” environment, alternative mathematical techniques have been developed that allow researchers and users to de-haze an image using feature-based techniques (below, left), distance-based techniques (below, center), and a combination of both feature- and distance-based mathematical algorithms (below, right).
    Research

    IMAGE PROCESSING: Image de-hazing technique uses skyless calibration

    Gail Overton
    March 1, 2009
    Researchers from the Technion-Israel Institute of Technology (Haifa, Israel) have developed an image de-hazing technique that estimates atmospheric polarization and haze-subtraction...
    Research

    NANOTECHNOLOGY: Photonic crystal aids quest for visible plasmon laser

    Hassaun A. Jones-Bey
    March 1, 2009
    Researchers from the New Jersey Institute of Technology (NJIT; Newark, NJ) have reported the first demonstration of laser threshold, gain, spectral line-narrowing, and feedback...
    (Courtesy of Princeton University)
    The conduction-band diagram for a QC laser shows a number of possible energy states. By injecting high-level electrons into the QC active region, emission occurs simultaneous at 80 K operating temperatures for both the 9.5 µm expected wavelength and an unexpected 8.2 µm wavelength. This second 8.2 µm wavelength exhibits lower threshold values and improved emission at temperatures higher than 85 K than its competing 9.5 µm wavelength.
    Research

    QUANTUM-CASCADE LASERS: Mid-IR QC laser exhibits dual-wavelength emission

    Gail Overton
    March 1, 2009
    A team of researchers has developed a mid-IR quantum-cascade (QC) laser that exhibits dual-wavelength emission.
    (Courtesy of Trumpf)
    A Trumpf 100 W fiber-coupled laser-diode module is passively cooled.
    Lasers & Sources

    PHOTONICS WEST 2009 PRODUCTS: More power to you

    John Wallace
    March 1, 2009
    This year’s show floor at SPIE’s Photonics West (February 24 to 29; San Jose, CA) offered high-power lasers galore.
    (Courtesy of Glimmerglass)
    This innovative MEMS mirror device is made from two silicon (Si) wafers fused together–a fabrication technique that will become increasingly important for intra- and interchip integrated optical communications.
    Research

    PHOTOMETRY: Persistent phosphors are seen in a new light

    John Wallace
    March 1, 2009
    So-called persistent phosphors can glow for up to several hours after optical excitation.
    (Courtesy of Thales Research and Technology)
    An external-cavity semiconductor ring-laser gyroscope achieves single-mode operation for high-quality rotation sensing. Two counterpropagating waves reflect off a 1/2VCSEL cavity and interfere in an external cavity, producing the “beat” signal that translates into rotation rate.
    Positioning, Support & Accessories

    OPTICAL GYROSCOPES: External-cavity semiconductor ring-laser gyro achieves single-mode operation

    Gail Overton
    March 1, 2009
    A team of scientists is the first to develop an external-cavity semiconductor ring-laser gyroscope that achieves single-mode operation.
    (Courtesy of Centro de Investigación Científica y de Educación Superior de Ensenada)
    A random laser is built using standard erbium/germanium-doped fiber containing fiber Bragg gratings and pumped by a 980 nm source. As the pump power and the number of gratings increase, the number of visible spectral modes increases as well. Even though intensity fluctuations are observed, these peak locations are stable with pump powers between 20 and 40 mW.
    Optics

    RANDOM LASERS: Random laser uses doped fiber and FBGs

    Gail Overton
    March 1, 2009
    Random lasers, which combine optical gain and light scattering within an active medium, have been demonstrated using a variety of materials and cavity configurations; however,...
    FIGURE 1. Commercially available mirror substrate materials rank differently in terms of dynamic stiffness–a parameter that is ideally as high as possible for improved performance.
    Optics

    OPTICS FOR SCANNING: Rapid scanning applications drive mirror design

    March 1, 2009
    Successful scanning requires integration of the mirror, its mounting, and the motor into a system called “M Cubed”–an integration process that requires tradeoffs in terms of materials...
    FIGURE 1. the 2DSI experimental setup includes an interferometer (beamsplitter C), which comprises a piezoelectrically vibrated mirror (mirror A).
    Test & Measurement

    FEMTOSECOND-PULSE CHARACTERIZATION: Novel 2DSI method measures sub-two-cycle laser pulses

    March 1, 2009
    A new pulse-characterization technique is designed for few- and single-cycle laser pulses. Called two-dimensional spectral shearing interferometry (2DSI), it has been demonstrated...
    FIGURE 1. Multispectral tuning (left) and polarization control (right) can be achieved with quantum-dot-based sensors that have plasmon-assisted photonic-crystal cavities (data is from a UNM/Caltech collaboration).
    Detectors & Imaging

    NEXT-GENERATION DETECTORS: Detector evolution results in ‘infrared retina’

    March 1, 2009
    With a single focal-plane array but multiple detector functionalities, an “infrared retina” can be combined with powerful signal-processing techniques to form a “poor man’s” infrared...
    FIGURE 1. Light from the seed laser (not shown), which emits 0.5 J pulses, is injected by the optics toward the left into the diode-pumped, helium-gas-cooled Mercury laser amplifier. The beam is amplified after passing through each laser head twice. Angular multiplexing allows the beam to bypass the initial injection mirror and instead traverse through the box of four mirrors and the Pockels cell to be reinjected for a series of two more passes–a total of four, one-way gain passes through each amplifier. After the final pass, the beam travels to the frequency converter, where the IR light is converted to green light, the second harmonic.
    Research

    HIGH-POWER SOLID-STATE LASERS: The Mercury laser moves toward practical laser fusion

    March 1, 2009
    The diode-pumped Mercury laser will deliver 100 J pulses at 10 Hz under automatic control, advancing the development of high-repetition-rate inertial laser fusion.
    FIGURE 1. In an amorphous-silicon thin-film solar cell an 8 nm p-type top layer, a 0.5 to 1 µm intrinsic middle layer, and a 20 nm n-type bottom layer are sandwiched between the top transparent oxide conductor and the rear contact. Most absorption is in the intrinsic layer.
    Research

    PHOTONIC FRONTIERS: THIN-FILM PHOTOVOLTAICS: The key to success is higher efficiency

    Jeff Hecht
    March 1, 2009
    Thin-film solar cells are making a run at the crystalline-silicon solar cells that dominate today’s photovoltaic market. Their allure is lower cost for large installations needed...
    Detectors & Imaging

    Laser-trapped microsphere becomes surface-measuring probe

    March 1, 2009
    A surface probe tipped with a microsphere can be scanned across the surface of a microlens or other microscale component to measure its 3-D coordinates, determining heights to...