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  • Volume 47, Issue 2

    • Volume 47, Issue 2

    FIGURE 1. Structured light systems project grids or other patterns, which reveal the contours of complex objects when viewed from the side. The lines look straight when projected onto a wall, but are distorted with projected onto people, furniture, or other uneven surfaces.
    Detectors & Imaging

    PHOTONIC FRONTIERS: GESTURE RECOGNITION: Lasers bring gesture recognition to the home

    Jeff Hecht
    Feb. 1, 2011
    Gesture-recognition technology is reaching the consumer market, thanks to new laser-based techniques that cut costs and improve system performance so it can be used to control...
    Detectors & Imaging

    Short-wavelength solar cells have high external quantum efficiency

    Gail Overton
    Feb. 1, 2011
    Indium gallium nitride (InGaN)-based semiconductors have large bandgaps, which has allowed the creation of ultraviolet and bright blue-emitting LEDs and lasers.
    Test & Measurement

    Volume actuator for interferometer controls air index fluctuations

    John Wallace
    Feb. 1, 2011
    Many precision optical distance- and displacement-measurement setups rely on optical interferometers to provide the data.
    79062
    Research

    LWIR imaging method noninvasively monitors honeybee hives

    Gail Overton
    Feb. 1, 2011
    Scientists now have a new tool to study the alarming collapse of honeybee populations.
    Research

    Researchers demonstrate first 3D photonic-crystal nanocavity laser

    Gail Overton
    Feb. 1, 2011
    Although lasing has been demonstrated in two-dimensional (2D) photonic-crystal nanocavities, researchers at the University of Tokyo have for the first time demonstrated lasing...

    More content from Volume 47, Issue 2

    Optics

    Silicon-on-sapphire ring resonators operate at a 5.5 μm wavelength

    John Wallace
    Feb. 1, 2011
    Researchers at the University of Washington and Cornell University have created the first silicon-waveguide ring resonators for wavelengths between 5.4 and 5.6 μm.
    FIGURE 1. The SBS threshold in fiber amplifiers can be raised by adopting LMA fibers with 20 or even 25 μm core diameter that allow the maximum power of single-frequency devices to exceed 50 W. A temperature gradient can be used to further increase the threshold to over 150 W.
    Fiber Optics

    FIBER AMPLIFIERS: High-power fiber amplifiers enable leading-edge scientific applications

    Feb. 1, 2011
    Improvements in high-finesse fiber amplifiers have boosted their optical output to the hundreds-of-watts range, making them an excellent tool for scientific uses such as trapping...
    (Courtesy of National Taiwan Ocean University)
    A schematic illustrates a continuous, high-throughput fabrication process for microlenses and microlens arrays in microchannels (a) before and (b) after applying voltages to the electrostatic-force-modulated (EFM)-3D gray mask. The microlenses and arrays can be dynamically adjusted during the fabrication process (c).
    Optics

    MICRO-OPTICS FABRICATION: 3D microfluidic mask method rapidly fabricates microlenses

    Gail Overton
    Feb. 1, 2011
    Microlenses and microlens arrays can be fabricated using a myriad of methods such as ultraviolet (UV) molding, hot embossing, photoresist and electron-beam lithography, and microjet...
    (All images courtesy of Cascade Technologies)
    FIGURE 1. A modular, ruggedized architecture includes interchangeable laser modules and dual-path-length gas cells, easily configured to meet particular application requirements.
    Lasers & Sources

    QUANTUM-CASCADE LASERS: Quantum-cascade lasers disrupt gas measurement technologies

    Iain Howieson
    Feb. 1, 2011
    A patented quantum-cascade laser intrapulse technique is at the heart of a ruggedized, accurate, industrial measurement platform designed to disrupt conventional gas measurement...
    (Courtesy of Rochester Institute of Technology)
    Mathematical modeling shows the force and torque exerted on an arc-shaped glass rod by uniform, nongradient illumination (a). An actual semicylindrical rod immersed in liquid and exposed to a 130 mW light source (in the z direction out of the paper or screen) lifts sideways from left to right due to the transverse optical lift force (b). The rod initially experiences torque, and then is translated with velocity vx toward the right. The lift force brings the rod out of focus in the z direction.
    Research

    OPTICAL FORCE PHENOMENA: Refractive object generates stable optical lift

    Gail Overton
    Feb. 1, 2011
    Rochester Institute of Technology researchers have mathematically predicted and experimentally observed the optical equivalent of aerodynamic lift.
    FIGURE 1. Devices are tested on a prober using an integrating sphere to assess performance characteristics during the sorting process known as binning.
    Test & Measurement

    LED TEST & MEASUREMENT: Optical testing is an essential aspect of making LEDs

    Feb. 1, 2011
    The performance of LEDs must be well characterized during production to ensure the devices meet end-user requirements across a range of operating parameters.
    A thin variable-thickness layer of Si between layers of polymer and SiO2, all fabricated on a Si substrate, serves as a 2D Luneburg lens for light traveling in the waveguide and polarized in the x direction (Ex).
    Optics

    SILICON PHOTONICS: Integrated Luneburg lens is created in silicon

    John Wallace
    Feb. 1, 2011
    One of the most interesting gradient-index lenses is the Luneburg lens, which takes the form of a sphere with a radially varying refractive index; its most well-known version ...
    Pennwell web 350 198
    Research

    MEDICAL OPTICS: Multimode optical fiber projects controllable light spots

    John Wallace
    Feb. 1, 2011
    Conventionally, an optical fiber carrying continuous light at a single wavelength transmits no data (other than that the light source is on). Amplitude modulation is what carries...
    (Courtesy of the J. Stefan Institute)
    Helical liquid-crystal structures self-assemble inside a cholesteric liquid-crystal (CLC) microdroplet, creating concentric shells of constant refractive index that form a dielectric structure known as a Bragg-onion optical microcavity, shown here as a drawing (a). This 3D laser emits omnidirectional light (b) and is tunable by simply modifying the temperature of the lasing medium.
    Optics

    MICROLASERS: Microlaser that emits in 3D now tunable

    Gail Overton
    Feb. 1, 2011
    Researchers at J. Stefan Institute and the University of Ljubljana have demonstrated for the first time fully tunable lasing from their 3D or omnidirectional-lasing dye-doped,...
    (Courtesy of the Fraunhofer-Institute for Applied Optics and Precision Engineering)
    When subjected to a scanning scratch test, a HfO2 coating with a total thickness of 270 nm failed by abrasion (a), while a 969 nm thick coating delaminated (b).
    Optics

    OPTICAL COATINGS: AR coating for sapphire has high scratch resistance

    John Wallace
    Feb. 1, 2011
    Sapphire is an exceptional optical material: in addition to its extreme hardness, it transmits light of wavelengths between 0.2 and 5.5 μm, is highly transparent for all but the...
    Software

    IN MY VIEW: Coming to a small screen near you?

    Jeffrey Bairstow
    Feb. 1, 2011
    This is not a column about Facebook or any of the other over-hyped, time-wasting social engineering networks. Nor is this column about lasers or optoelectronics.
    1304qa Chang New
    Executive Forum

    Business Forum: Is now a good time to seek further education?

    Milton Chang
    Feb. 1, 2011
    Q: I was fortunate to get hired as a CEO during the telecom bubble but have not had a good job since. I have been looking at the mobile space and also thinking about an MBA. I...
    (Image courtesy of X.Y. Wu, Quantum Dot Corp.)
    FIGURE 1. Experimental results show drastically reduced photobleaching in cell imaging with quantum-dot (QD) labels (red) compared to organic dye molecules (green). Images shown are complementary; the nucleus is labeled with QD 630-steptavidin and the periphery labeled with AlexaFluor 488 in the top panel, whereas the inverse labeling scheme is used in the bottom panel.
    Spectroscopy

    FLUORESCENCE IMAGING: Understanding fluorescence blinking is the first path to an imaging solution

    Feb. 1, 2011
    Understanding the microscopic origin of fluorescence blinking in quantum emitters such as quantum dots, rods, and wires is crucial in designing novel structures that show a substantial...
    FIGURE 1. Scanning electron micrograph of an air-bridge Schottky barrier diode made at CNR-IFN shows that the metal connection between the anode pad and the Schottky junction has been suspended in order to reduce parasitic capacitance. The suspended structure was obtained by wet chemical removal of the GaAs under the metal bridge, after lithographic definition of the two mesas.
    Spectroscopy

    TERAHERTZ DETECTORS: Air bridge improves terahertz detector response time

    Feb. 1, 2011
    Terahertz detectors with microsecond response time can be obtained by fabrication of air-bridge pixels compatible with monolithic array integration, due to both active region ...
    (Courtesy of University of California–San Diego)
    FIGURE 1. An optogenetic functional magnetic resonance imaging (ofMRI) technique delivers 473 nm blue light to the motor cortex region of a rat’s brain (a). The channelrhodopsin (ChR2) expressing region in the brain is co-localized with the fluorescent tag as shown in the confocal microscopy images (b). A blood-oxygenation-level dependent (BOLD) signal appears in the light-activated brain (c; right) in the presence of ChR2, but not in the brain treated with a saline injection (c; left), indicating that selective stimulation of excitatory neurons expressing ChR2 is the source of the BOLD signal.
    Research

    PHOTONICS APPLIED: BIOPHOTONICS: Optogenetics—Turning light bulbs on in the brain

    Gail Overton
    Jan. 25, 2011
    An emerging form of phototherapy, optogenetics uses light to selectively activate light-sensitive proteins delivered to the brain and other tissues, promising a new host of medical...