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  • Volume 56, Issue 08

    • Volume 56, Issue 08

    FIGURE 1. The key components of a Raman spectroscopy system are the laser, detector, spectrograph, and probe.
    Spectroscopy

    High-performance near-infrared Raman for clinical application

    Peng Zou, Ph.D.
    Aug. 11, 2020
    Technology advances are enabling Raman spectroscopy for application as a clinical tool.
    (Courtesy of Morgan Trassin)
    FIGURE 1. At ETH Zurich, an Astrella amplifier maintains output stability in spite of its proximity to a deposition chamber that reaches internal temperatures as high as 950°C.
    Lasers & Sources

    Revisiting the industrial revolution in scientific lasers

    Allan Ashmead
    Aug. 11, 2020
    A look is taken at how the industrial approach to reliability in ultrafast scientific lasers has resulted in research tools that deliver on their promise.
    2006 Lfw Nb Z05
    Lasers & Sources

    Toothed iris diaphragm helps control radial intensity inside a femtosecond-laser filament core

    John Wallace
    Aug. 11, 2020
    A “stellate” iris diaphragm controls intensity inside a filament, while drilling into a metal sheet characterizes filament beam shape.
    2008 Lfw Bf Z01
    Executive Forum

    New photonics stock indices: A spotlight on the ecosystem of impact and opportunities

    John Dexheimer
    Aug. 11, 2020
    This is the inaugural release of the Photonics 40+ stock indices provided by LightWave Advisors.
    FIGURE 1. A simple planar waveguide of a high-index material embedded in a block of low-index material that serves as the cladding. The waveguide also may be deposited on top of a lower-index material, with air serving as the cladding on sides and top, or embedded in the surface layer, with air serving as the top cladding. For most applications, the waveguide is thin and narrow.
    Optics

    Waveguide optics: Going beyond classical fiber optics

    Jeff Hecht
    Aug. 11, 2020
    Building integrated-photonic circuits into a new generation of technology requires expanding our view of light guiding to a broad range of optics that transport and manipulate...

    More content from Volume 56, Issue 08

    FIGURE 1. Raman spectra of common biological molecules: cholesterol, triolene, acitin, DNA, oleic acid, collagen (type 1), glycogen, and lycopene.
    Lasers & Sources

    Healthcare: Laser-based point-of-care testing and biomodulation therapy have a bright future

    Robert V. Chimenti
    Aug. 11, 2020
    Low-power, nondestructive medical laser applications will help shape the future of photonics in healthcare.
    FIGURE 1. A new, low-cost bidirectional optical subassembly (BOSA) uses a single glass-sealed conventional TO-can package and incorporates optical transmitting and receiving functions into a silicon optical bench.
    Fiber Optics

    Assembly solution addresses TO-can photonic device manufacturing challenges

    Limin Zhou
    Aug. 11, 2020
    The high-volume, high-mix nature of new TO-can packages for high-speed DCI and 5G wireless network rollouts require ±1~2 µm machine accuracy and flexibility to quickly handle ...
    FIGURE 1. The leaf blend grade verification system consists of an enclosure, tungsten halogen lamps, a cooling fan, and a hyperspectral camera.
    Detectors & Imaging

    Hyperspectral imaging system grades agricultural products

    James Carroll
    Aug. 11, 2020
    Based on factors such as growing location, weather, leaf position on the plant, color, and texture, tobacco is divided into grades, a process previously done by manual inspection...
    The LambdaVision artificial retina generates an ion gradient from ordered layers of bacteriorhodopsin to restore useful sight when implanted in place of irretrievably damaged photoreceptors in the eye.
    Detectors & Imaging

    Self-powered artificial retina uses light-activated protein to enable ‘meaningful sight’

    Richard Gaughan
    Aug. 11, 2020
    An artificial retinal implant based on the photosensitive molecule bacteriorhodopsin can potentially reach higher resolutions than conventional semiconductor-based retinal implants...
    Absorption (1 - reflectivity R) spectra of plasma-patterned (a) and conventionally etched (b) AZO metasurfaces show several spectral bands; notable is the similarity in spectral absorption for the two different surfaces. Different colors correspond to different metasurface feature sizes: red is 650 nm, green is 850 nm, dark blue is 1050 nm, and violet is 1250 nm. The solid black line is the absorption of a planar AZO film with no patterning.
    Optics

    Oxygen plasma patterning technique forms optical metasurfaces that remain planar

    John Wallace
    Aug. 11, 2020
    Rather than etching a metasurface layer that could cause problems for further layers, plasma patterning leaves the metasurface layer flat.
    An optical fiber or waveguide has segments that alternate between normal and anomalous dispersions (NA and AD; a); this allows supercontinuum generation to occur with the deleterious effects of dispersion minimized. A plot of normalized energy density spectrum versus propagation for a supercontinuum-generating fiber with alternating dispersion (b) shows that the spectral broadening keeps increasing with length and is not limited by dispersion. A plot of intensity and shape of the pulse vs. propagation length (c) shows that the undesired pulse stretching in the ND fiber segments is compensated by the AD segments.
    Lasers & Sources

    Alternating dispersion boosts supercontinuum bandwidth without need for more laser power

    John Wallace
    Aug. 11, 2020
    An optical fiber or waveguide with segments of alternate-signed dispersion eliminates stagnation of spectral broadening due to dispersion effects.
    2008 Lfw Nb 1
    Optics

    Terahertz beam steering uses 3D-printed active diffraction grating

    John Wallace
    Aug. 11, 2020
    A variable-period diffraction grating actively steers a terahertz beam by compressing the grating to various degrees; the device can be driven by a speaker for fast beam-steering...
    Optics

    Study of optically clear epoxies under ionizing radiation results in one best choice

    John Wallace
    Aug. 11, 2020
    Scientists at Fermilab studied optically clear cements for use in scintillator optics; tests under ionizing radiation from their accelerator produced a clear winner.
    2008 Lfw Nb 2 Cropped
    Optics

    SLM for laser-based materials processing handles pulsed laser powers up to 400 GW/cm2

    John Wallace
    Aug. 11, 2020
    A spatial light modulator for laser processing of carbon-fiber-reinforced plastics and low-dielectric-constant materials has improved dielectric films that boost its power-handling...
    2008 Lfw Nb 3
    Lasers & Sources

    Arrays of silicon, rather than metallic, nanoparticles key to improving nanophotonic devices

    John Wallace
    Aug. 11, 2020
    The use of silicon in regular nanophotonic arrays can boost light emission from associated organic molecules by 20-fold.
    2105 Lfw Lpms Supp 9a
    Commentary

    Light and matter interaction

    John Lewis
    Aug. 11, 2020
    Near-infrared Raman spectroscopy, photonics in healthcare, industrialized scientific ultrafast lasers, and waveguide optics are just a sampling of what's featured in the August...
    (Image credit: Johns Hopkins University; adapted from M. Graham et al. [1]))
    This catheter contains a 1-mm-diameter optical fiber that pipes laser pulses at a 750 nm wavelength to the heart region to perform photoacoustic imaging. The pulses each have an energy of 2.98 mJ at the fiber tip; repetition rate is 600 Hz.
    Fiber Optics

    Photoacoustic imaging could make catheter-based heart procedures safer

    John Wallace
    April 17, 2020
    An optical fiber in a cardiac catheter produces photoacoustic signals at the tip of the catheter; robotic vision guides the catheter.