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    • Volume 45, Issue 3

    More content from Volume 45, Issue 3

    (Courtesy of University College Dublin)
    Ultrafast laser pulses are spectrally broadened in a gas-filled fiber, allowing them to be compressed to few-cycle widths. Changing the gas pressure changes the pulse width and bandwidth.
    A new approach to nonlinear spectroscopy has shed some light on the electron coupling in a photosynthetic protein.
    March 1, 2009
    Though significant progress has been made in quantum communications using polarization-entangled photons practical implementation is difficult, considering that single-mode fiber...
    March 1, 2009
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    Introduced at SPIE’s Photonics West 2009, the WaveShaper liquid-crystal-on-silicon (LCoS)-based family of optical processors from Finisar (Sunnyvale, CA) offer more than just ...
    March 1, 2009
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    Researchers at Stanford University (Palo Alto, CA) and the University of Colorado at Boulder have demonstrated for the first time a method for 3-D optical imaging of objects smaller...
    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...
    March 1, 2009
    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.
    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...
    March 1, 2009
    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.
    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.
    March 1, 2009
    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).
    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...
    March 1, 2009
    FIGURE 1. the 2DSI experimental setup includes an interferometer (beamsplitter C), which comprises a piezoelectrically vibrated mirror (mirror A).
    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...
    March 1, 2009
    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.
    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...
    March 1, 2009
    (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.
    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,...
    March 1, 2009
    (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.
    A team of scientists is the first to develop an external-cavity semiconductor ring-laser gyroscope that achieves single-mode operation.
    March 1, 2009
    (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.
    So-called persistent phosphors can glow for up to several hours after optical excitation.
    March 1, 2009
    (Courtesy of Trumpf)
    A Trumpf 100 W fiber-coupled laser-diode module is passively cooled.
    This year’s show floor at SPIE’s Photonics West (February 24 to 29; San Jose, CA) offered high-power lasers galore.
    March 1, 2009
    (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.
    A team of researchers has developed a mid-IR quantum-cascade (QC) laser that exhibits dual-wavelength emission.
    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...
    March 1, 2009
    (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).
    Researchers from the Technion-Israel Institute of Technology (Haifa, Israel) have developed an image de-hazing technique that estimates atmospheric polarization and haze-subtraction...
    March 1, 2009
    (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.
    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...
    March 1, 2009
    (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.
    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...
    March 1, 2009
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    The new 48-page catalog from Fermionics Opto-Technology contains specs, drawings, and photos describing InGaAs photodiodes for communications, monitoring, instrumentation, and...
    March 1, 2009
    There have been some remarkable developments in a number of laser technologies recently–something for everyone, in fact!
    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.
    March 1, 2009
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    Digital light source RS-5-93K characterizes the performance of image sensors and image-sensor systems.
    March 1, 2009
    (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.
    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...
    March 1, 2009
    FIGURE 1. Reflectivity measurements are plotted from center to edge for a 320-mm-diameter extreme-ultraviolet test mirror with a 1.6-steradian collection angle.
    Despite its system complexity, extreme-ultraviolet lithography (EUVL) is likely to be the next-generation technology to achieve 22 nm resolution and beyond, if sufficient source...
    Feb. 26, 2009
    Student needs steadily grow in breadth and depth over time. Given increasing demand and today's lean economic times, it is especially important that organizations continue their...
    Feb. 25, 2009
    FIGURE 1. A 1 kW master-oscillator power-amplifier (MOPA) fiber laser system is based on commercially available fiber, components, and pump diodes.
    Improved power scaling of fiber lasers is being enabled by advances in high-brightness pump laser diodes—specifically, higher efficiency of the pump semiconductor material itself...
    Sept. 22, 2008