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  • Volume 55, Issue 08

    • Volume 55, Issue 08

    FIGURE 1. Two laser resonators are depicted here: a linear resonator with output coupling at an end mirror, and a unidirectional ring laser.
    Lasers & Sources

    Laser Design: Understanding and optimizing laser resonator designs: An overview

    Dr. Rüdiger Paschotta
    Aug. 1, 2019
    The design of a laser resonator is an essential part of a laser design and often a difficult task—learn how to determine required resonator mode properties and find suitable designs...
    FIGURE 1. Broad clinical applications of photobiomodulation therapy aim at reducing pain and inflammation while promoting healing and regeneration.
    Lasers & Sources

    Phototherapy: Photobiomodulation therapy—easy to do, but difficult to get right

    Aug. 1, 2019
    When non-ionizing, non-thermal light treatment called photobiomodulation (PBM) therapy is used in the right dose and clinical context, this treatment can reduce pain and alleviate...
    FIGURE 1. This 905 nm four-channel surface-mount laser provides >480 W peak power.
    Lasers & Sources

    Lasers for Lidar: Monolithic multichannel laser moves automotive lidar toward practical use

    Ann Russell
    Aug. 1, 2019
    A four-channel laser and ultrafast driver delivers more than 480 W peak power in 2 ns pulses.
    FIGURE 1. The mode of operation of a DCFC for extraction of fluorescence emission is shown.
    Detectors & Imaging

    Optical Coherence Tomography/Fluorescence Imaging: Fiber assembly enables efficient multimodal endoscopy

    Aug. 1, 2019
    Double-clad fiber couplers (DCFCs) enable seamless and efficient combinations of modalities for robust fiber-based imaging and other biomedical applications.
    FIGURE 1. A diagram of rigid-body motions shows the six possible degrees of freedom. For rotationally symmetric parts, the axis of symmetry is assumed to be along the Z axis.
    Optics

    Aspheres: Removing alignment errors from measurements of spherical, aspheric, and freeform optics

    Paul Murphy
    Aug. 1, 2019
    Optical surface measurements include alignment error from rigid-body position uncertainty; challenges exist when fitting such errors on aspheres and freeforms.

    More content from Volume 55, Issue 08

    (Adapted from A. Orth et al. [Ref. 11])
    FIGURE 1. The tip of a 30,000-core optical fiber bundle is shown next to an Australian 5 cent coin for scale (left) and a zoomed-in image (right) reveals a small region of the fiber bundle facet (dashed red box in left). Each core is roughly 2 µm in diameter and separated from its neighbors by an average of 3.3 µm.
    Fiber Optics

    Fiber-optic Components: Fiber-optic bundles provide 3D stereo imaging

    Aug. 1, 2019
    With each fiber acting as an independent pixel, coherent fiber bundles transmit more information than just a 2D representation of an image; specifically, the spatial light field...
    FIGURE 1. In the scalable setting of a spatial photonic Ising machine, binary spins are encoded in the phase of a laser beam (green) by spatial modulation. Tailoring of the beam’s amplitude fixes spin-spin interaction. To find the ground-state spin configuration, the machine recurrently evolves according to a feedback signal from the camera plane. By design, maximizing the intensity in a target region (blue square) corresponds to a spin state with minimum energy.
    Software

    Photonics Modeling: Optical Ising machines solve complex engineering, science, and even business problems

    Aug. 1, 2019
    Researchers have built the largest photonic Ising machine to date—an optical processor for solving difficult optimization problems by modeling interacting spins via a spatially...
    (Image credit: U.S. Naval Research Laboratory)
    Shown are tuning curves for three quantum dots positioned on the waveguide at the locations shown in the inset, to achieve identical emission (a). High-resolution Fabry-Perot interferometer measurements show all three quantum dots simultaneously from an output coupler with identical emission wavelength (b).
    Lasers & Sources

    Quantum Sources: Squeezed quantum dots create coherent streams of quantum-ready photons

    Gail Overton
    Aug. 1, 2019
    By squeezing quantum dots using unique semiconductor-based processes, coherent single photons are generated that can be used for on-chip quantum photonics that demand identical...
    Several rotationally symmetric cavities are etched into a silicon wafer for glassblowing of 0.9-mm-diameter (left) and 1.8 mm (right) axicons.
    Optics

    Optical Fabrication: Glassblowing technique creates arrays of axicon lenses

    John Wallace
    Aug. 1, 2019
    Axicon lenses, which are useful for microfabrication, OCT, and other applications, can now be easily made in large quantities by glassblowing.
    A fast, low-cost, highly sensitive diffuse optical imaging system acquires optical transmission images dorsally to provide objective, quantitative analysis for rheumatoid arthritis (RA) diagnosis and monitoring.
    Test & Measurement

    Spectroscopy/Optical Imaging: Fourier-transform analysis helps optical method improve RA detection

    Barbara Gefvert
    Aug. 1, 2019
    A noninvasive near-infrared diffuse optical imaging (DOI) system combines 3D digital imaging and infrared (IR) spectroscopy to map blood content in a patient’s hand for detection...
    (Image credit: University of California, Riverside)
    A microresonator pumped with a CW laser (a) produces a microcomb with stable or chaotic behavior, as well as pure quartic soliton (PQS) pulse trains depending on the pump frequency (b). A high-energy random initial state will evolve with time and settle to a stable pulse with near-Gaussian power profile (c) and uniform power spectrum having a remarkable 3 dB bandwidth (d).
    Lasers & Sources

    Frequency-comb Sources: One microresonator-based soliton comb replaces multiple WDM lasers

    Gail Overton
    Aug. 1, 2019
    Microresonator-based pure quartic solitons (PQSs) efficiently convert CW laser light into frequency combs with the power uniformity of individual CW lasers.
    1908 Lfw Nb F1
    Fiber Optics

    Nanoparticle-embedded stretchy optical fibers monitor body temperature

    Gail Overton
    Aug. 1, 2019
    Polymer optical fibers embedded with temperature-sensitive nanoparticles conform to the skin and endure large strain deformations that provide ratiometric temperature data, verified...
    1908 Lfw Nb F2
    Optics

    Metasurface optic for Gaussian beams accepts a nonplanar input beam

    John Wallace
    Aug. 1, 2019
    Most metasurface optics only accept plane-wave beams; a new hybrid metal-dielectric metastructure focuses a diverging Gaussian beam back on itself.
    1908 Lfw Nb F3
    Optics

    Large-field cryogenic objective mirror has nearly diffraction-limited performance

    John Wallace
    Aug. 1, 2019
    Designed for use while being cooled by liquid helium, a cryogenic objective mirror with an aspherical surface has a NA of 0.93 and a field radius of 36 µm, large enough to image...
    Test & Measurement

    QCL-based infrared spectroscopic ellipsometer rapidly acquires data

    John Wallace
    Aug. 1, 2019
    Built around a quantum-cascade laser (QCL), the first laser-based infrared spectroscopic ellipsometer will aid biologists and materials scientists.
    John Ambroseo, President and CEO of Coherent.
    Lasers & Sources

    Business Forum: Laser markets evolve, price battles continue—an interview with John Ambroseo

    Andreas Thoss
    Aug. 1, 2019
    An interview with the president and CEO of Coherent reveals a laser industry still changing, driven by commodization and continual advances in technologies and applications.
    2105 Lfw Lpms Supp 9a
    Commentary

    Lasers for lidar and more

    John Lewis
    Aug. 1, 2019
    Editor in chief John Lewis introduces Laser Focus World’s August 2019 issue, which includes trends in photonics technologies, applications, and markets.