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  • Volume 55, Issue 03

    • Volume 55, Issue 03

    Conard 720
    Test & Measurement

    Business Forum: Mastering a changing laser market

    Conard Holton
    March 20, 2019
    Changes in end-user markets are changing laser and photonics markets, and more significant changes are coming as photonics find a foothold in the fast-emerging markets for quantum...
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    Research

    Laser light sources

    John Lewis
    March 20, 2019
    Editor in Chief John Lewis discusses laser light sources and invites you to enjoy Laser Focus World’s March 2019 issue, which includes trends in photonics technologies, applications...
    (Courtesy of Sensors Unlimited)
    FIGURE 1. Utah’s Salt Lake Valley occasionally experiences an atmospheric phenomenon that traps air pollution for days or weeks at a time. During these atmospheric inversion events, ground-level visibility is severely reduced. These images taken from a video show visible imagery (a) and shortwave-infrared (SWIR) imagery (b) during a period of very low ground-level visibility on December 7, 2017 at approximately 3:30 pm MST (to see the video, visit https://youtu.be/3cBkfQb8vxQ). The SWIR imagery was captured at 60 fps with the Sensors Unlimited GA1280JSX mini-SWIR area camera and a 200 mm SWIR-optimized f/1.6 lens. The visible imagery was captured with a Nikon D5100 DSLR camera in video mode and a 55–200 mm f/4.5-5.6 lens. Both sets of imagery are cropped, but are otherwise unchanged.
    Detectors & Imaging

    Photonics Products: Imaging for Surveillance and Security: SWIR cameras cut through haze for surveillance and security

    John Wallace
    March 1, 2019
    Covert operations commonly use thermal imaging and/or night vision, but the shortwave infrared (SWIR) band has its own advantages, such as seeing through atmospheric haze.
    FIGURE 1. This schematic shows the building blocks for a silicon photonics probing system.
    Optics & Design

    Silicon Photonics: Automated wafer-level probing meets silicon photonics

    March 1, 2019
    Fully integrated and automated wafer-probing systems enable silicon photonic chip designers to characterize and qualify their designs faster than ever.
    (Image credit: MIT Lincoln Laboratory)
    Shown is the SBS lasing setup with independent pump lasers and controlled coupling scheme, with linewidth optimized for a resonant cavity coupling ratio of around 1.3%.
    Research

    Fiber Lasers: Ultranarrow Brillouin fiber laser has built-in temperature stability

    Gail Overton
    March 1, 2019
    Dual stimulated-Brillouin scattering (SBS) lasers in an optical fiber cavity generate an ultranarrow-linewidth signal that can be used to temperature-stabilize the laser by detecting...

    More content from Volume 55, Issue 03

    A glass phosphor converter layer for a laser headlight (a) has high thermal stability and can be made at a relatively low temperature of 750°C. In comparison to a silicone-based phosphor converter layer, the glass-based device, when subjected to thermal aging tests, shows much lower lumen loss (b), much less color shift (c), and a much smaller drop in quantum efficiency (d).
    Lasers & Sources

    Automotive Lighting: Laser headlight module uses stable, easy-to-manufacture glass phosphor

    John Wallace
    March 1, 2019
    A glass-based phosphor converter layer for automotive headlights is much more stable than silicone, less expensive than ceramic.
    (Image credit: EPFL)
    A chip-based, compact laser injection-locked soliton Kerr frequency comb (a) consists of a laser diode chip butt-coupled to a silicon nitride photonic chip with microresonators that create an injection-locked soliton Kerr frequency comb (b). A magnified view shows the indium phosphide laser diode chip (c), which is part of the overall microcomb architecture (d). Also shown is a false-colored SEM image of the waveguide cross-section (e).
    Test & Measurement

    Optical Frequency Combs: Smallest chip-based ‘microcomb’ consumes just 1 W in a 1 cm3 package

    Gail Overton
    March 1, 2019
    Leveraging advances in ultrahigh-Q-factor Si3N4 microresonators and commercial chip-scale InP laser diodes, a high-quality frequency comb enabled by self-injection locking consumes...
    (Courtesy of the Capasso Lab/Harvard SEAS)
    These subwavelength anisotropic nanostructures that are arrayed across the surface of a metalens can focus light regardless of its polarization, doubling the efficiency of the lens. The titanium dioxide nanofins were optimized in shape using a “particle swarm” algorithm.
    Optics & Design

    Metasurface Optics: Broadband achromatic metalens focuses all polarizations

    John Wallace
    March 1, 2019
    Created at Harvard SEAS, the metasurface lens has a large bandwidth of 460 to 700 nm and a numerical aperture of 0.2.
    (Courtesy of UNM)
    FIGURE 1. When a random laser is filled with a gain medium and then pumped with a single-colored laser, microscopic air channels in the optical fiber make the output beam highly directional and stabilize its spectrum.
    Research

    Raman Fiber Lasers: Random laser advances: Fiber optics and lasing vegetables

    Barbara Gefvert
    March 1, 2019
    A disordered optical fiber using a highly porous glass is combined with carotenoids to form a Raman laser.
    Content Dam Lfw Print Articles 2019 03 1903lfw Nb F1
    Research

    Quantum-dot mode-locked laser on silicon transmits data at 4.1 Tbit/s

    John Wallace
    March 1, 2019
    The gallium arsenide (GaAs)-based quantum-dot laser’s frequency comb contains 64 channels with linewidths of 1.8 kHz.
    Content Dam Lfw Print Articles 2019 03 1903lfw Nb 2
    Research

    TERS images single-stranded DNA without amplification

    Gail Overton
    March 1, 2019
    Tip-enhanced Raman spectroscopy (TERS) of single-stranded DNA at the molecular level can rapidly identify DNA structure and sequence information without expensive polymerase chain...
    Positioning, Support & Accessories

    With leads reversed, experimental IR LED can cool things

    John Wallace
    March 1, 2019
    An infrared LED exploits photon tunneling and suppressing emission of photons via reverse bias to cool at a rate of 6 W/m2.
    Content Dam Lfw Print Articles 2019 03 1903lfw Nb F3
    Optics

    Fiber-based polymer microtips produce Bessel-like beams

    John Wallace
    March 1, 2019
    Polymer microtips can be formed in a straightforward process on the end of single-mode fibers, enabling the production of Bessel-like light beams for particle guiding and other...
    FIGURE 1. Conventional lasers use an optical cavity that traps light at certain resonances, so the field localization and quality factor depend weakly on the geometry; by contrast, the field localization of anapoles and bound states in the continuum (BICs) of metamaterial optics depends on the geometry.
    Optics

    Nonlinear Optics: Engineered metaoptics forge new nonlinear devices

    March 1, 2019
    Recent progress in metaoptics driven by Mie resonances of high-index dielectric nanoparticles provides a novel platform for subwavelength localization of light in supercavities...
    (Adapted from B. Redding, M. A. Choma, and H. Cao [4])
    FIGURE 1. A schematic (a) illustrates the principle of a random laser with low spatial coherence; optical scattering in a random medium enhances stimulated emission of photons. The black circles denote scattering centers and the orange dots are excited atoms. The calculated spatial intensity distribution (b) of a lasing mode in a 2D disordered structure is shown. A resolution chart is imaged under illumination by a random laser (c) and a standard helium-neon (HeNe) laser (d). The random laser has low spatial coherence and suppresses speckle noise.
    Research

    Laser Coherence: Spatial coherence engineering of lasers enhances use for illumination

    March 1, 2019
    Spatial-coherence tailoring extracts more image information from laser-illuminated microscopes and other optical systems.
    FIGURE 1. Aberrations remaining in OCT data produced with hardware adaptive optics (HAO) can be corrected with post-processing using computational adaptive optics (CAO).
    Detectors & Imaging

    Optical Coherence Tomography: Innovations in OCT

    Barbara Gefvert
    March 1, 2019
    Optical coherence tomography (OCT) continues to develop, leveraging advances in computing power, innovation in system design, and application of artificial intelligence.