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  • Volume 54, Issue 09

    • Volume 54, Issue 09

    FIGURE 1. For many materials, blue light is absorbed better than infrared, leading to faster and better laser materials processing.
    Lasers & Sources

    Novel Lasers: Blue direct-diode lasers extend industrial laser capability

    Sept. 2, 2018
    A high-power and high-brightness blue direct-diode laser system that processes copper with high efficiency and low excess heat.
    (Courtesy of Cascade Microtech, a FormFactor company)
    FIGURE 1. Two H-811 miniature hexapods made by PI for fast, multichannel parallel alignment (FMPA) are mounted on a Cascade Microtech silicon-photonics wafer prober.
    Positioning, Support & Accessories

    Photonics Products: Vibration Control: Hexapods provide precise positioning in six axes

    John Wallace
    Sept. 2, 2018
    Hexapods come in high-precision, high-accuracy, and high-load versions and serve to align optics for assembly, simulate or isolate vibration, and many other tasks.
    An alumina (Al2O3) waveguide fabricated via atomic layer deposition (ALD) has very low propagation loss in the blue and near-UV spectrum; a line fit (inset) from experimental data for TE-polarized light at a 405 nm wavelength in a 600-nm-wide waveguide shows an attenuation of 1.61 dB/cm.
    Research

    Waveguide Optics: Novel alumina optical waveguides have very low loss in the blue and near-UV

    John Wallace
    Sept. 2, 2018
    A 600-nm-wide amorphous aluminum oxide waveguide has a transmission loss of only 1.61 dB/cm at a 405 nm wavelength.
    The holographic illumination setup, by researchers at Technische Universität Dresden, relies on a spatial light modulator (SLM), incorporating a ferroelectric liquid crystal, for focusing on the sample. The setup also includes a 450-nm-emitting laser diode, lenses (L1–L3), a nonpolarizing beamsplitter, and a linear polarizer. A camera mounted on a commercial inverted microscope captures illumination of the specimen.
    Research

    Optogenetics/Neuroscience: Digital holographic lighting enables human neural-network research

    Barbara Gefvert
    Sept. 2, 2018
    Holographically shaped illumination for optogenetics enables stimulation of single neurons at high spatiotemporal resolution.
    A fiber-optic pressure sensor (a) includes a silicon diaphragm that forms a Fabry-Perot (F-P) cavity with the end of a single-mode fiber (SMF); the fiber also contains a fiber Bragg grating (FBG). Both the F-P cavity and the FBG independently measure temperature and pressure; the simultaneous measurements allow the temperature effects to be subtracted out, leaving only the desired pressure data. An interference spectrum (b) of the fiber-optic sensor shows both the F-P resonances and a temperature sign produced by the FBG.
    Research

    Fiber-optic Sensing: Simple, rugged fiber-optic pressure sensor works over large temperature ranges

    John Wallace
    Sept. 2, 2018
    The combination of a Fabry-Perot cavity and a fiber Bragg grating allows a fiber-optic sensor to produce pressure data without a dependence on temperature.

    More content from Volume 54, Issue 09

    (Image credit: NIST)
    A schematic diagram shows spectral combination of the integrated devices and the frequency chain that multiplies the 10 MHz clock to the optical domain (a). Also shown is the combined spectrum of the 22 GHz microcomb with the III-V tunable laser in the communications C-band (b), as well as the combined spectrum of the octave-spanning silicon-nitride microcomb and the 22 GHz comb measured with an optical spectrum analyzer (c).
    Test & Measurement

    Wavelength References: Tunable laser, frequency combs, and integrated photonics forge an optical frequency synthesizer

    Gail Overton
    Sept. 2, 2018
    Optical frequency combs and integrated photonics convert the output from a tunable laser into an on-demand, frequency-stabilized optical output.
    Refractive index vs. temperature was measured for the various amorphous polyimides; for example, the BTDT polyimide (a) and linear least-squares lines fit to the data. The volume coefficient of thermal expansion (VCTE) vs. 1/m* (where m* is the molecular weight) was calculated from the data for the various polyimides (b) and the results (colored dots) compared to data (open black dots) from a 2017 study of on crystalline polyimides done by Ishige et al [2]. The VCTE for the amorphous polyimides is significantly lower than those for the crystalline polyimides.
    Research

    Polymer Optics: Amorphous polyimides are thermally stable, promising for optics

    John Wallace
    Sept. 1, 2018
    Amorphous polyimides have thermo-optic coefficients and volume coefficients of thermal expansion much lower than the widely used PMMA and polycarbonate polymers used in optics...
    Conard Holton2
    Research

    Changing scenes

    Conard Holton
    Sept. 1, 2018
    Continuing a long tradition of technical excellence, the editorial team at Laser Focus World welcomes new editor in chief John Lewis.
    (Image credit: LioniX International, University of Athens, and West Attica)
    A conceptual illustration of the free-space optical (FSO) transceiver for intra-datacenter interconnects is shown (a), whereby the exiting beam can be configured to connect to other racks (b) via vertical or horizontal (2D) beam steering, thus enabling inter-rack communication architectures.
    Optics

    Free-space Optical Communication: Datacenter cabling bottleneck cleared via free-space optical interconnects

    Gail Overton
    Sept. 1, 2018
    The cabling complexity and high power consumption of traditional fiber-to-fiber optical interconnects and transceivers can be remedied using FSO interconnects and 2D beam steering...
    Content Dam Lfw Print Articles 2018 09 1809lfw Nb F3
    Detectors & Imaging

    Maximizing wireless power delivery demands understanding of laser/PV characteristics

    Gail Overton
    Sept. 1, 2018
    To optimize wireless power delivery using lasers and photovoltaics, the temperature and beam density must also be studied rather than output characteristics only.
    Content Dam Lfw Print Articles 2018 09 1809lfw Nb F5
    Detectors & Imaging

    Sony develops smallest-pixel-pitch, highest-resolution 0.5 in. microdisplay

    John Wallace
    Sept. 1, 2018
    By depositing the color filter directly on the silicon substrate, reducing the distance to the light-emitting layer, the Sony microdisplay has improved viewing angle and resolution...
    Content Dam Lfw Print Articles 2018 09 1809lfw Nb F2
    Research

    Solar-blind UV photodetector has nanocrystals synthesized by using ion implantation

    John Wallace
    Sept. 1, 2018
    A solar-blind photodetector is composed of nanocrystals of gallium oxide, a promising semiconductor for deep-UV detection.
    Content Dam Lfw Print Articles 2018 09 1809lfw Nb F1
    Research

    Understanding graphene plasmonic limits to guide future nanophotonic engineering

    Gail Overton
    Sept. 1, 2018
    Only by understanding limitations of plasmonic polariton confinement within materials like graphene can future nanophotonic engineering be improved.
    1304qa Chang New
    Research

    Business Forum: Should I work for this photonics company?

    Milton Chang
    Sept. 1, 2018
    Analyze potential job offers at startup companies by understanding the company’s financial goals, the short- and long-term potential of the product or application, and whether...
    FIGURE 1. Shown is measured permittivity of ITO thin films fabricated with different temperatures during RF sputtering; carrier concentration and thus ENZ wavelength can be routinely designed. The Drude model (red curves) describes the permittivity as a function of wavelength.
    Optics & Design

    Thin-film Coatings: Ultrathin tunable conducting oxide nanofilms create broadband, near-perfect absorbers

    Sept. 1, 2018
    Ultrathin, tunable conducting oxide nanolayers have many potential applications in flat nonlinear and magneto-optical devices, tunable metamaterial devices, and quantum zero-index...
    FIGURE 1. A >0.3 mm glass wafer with isotropically etched channels is bonded with room-temperature UV adhesive to a 1-mm-thick glass wafer; the glass:glass bond preserves bioactivity of encapsulated biomolecules/cells.
    Lasers & Sources

    Lab-on-a-Chip/In Vitro Diagnostics: Facilitating microfluidics with material selection

    Sept. 1, 2018
    Microfluidics is an enabling technology that requires robust material for peak performance.
    FIGURE 1. A schematic shows a simple HOM interferometer used to measure the effects of a photon’s spatial properties on its group velocity; such interferometers were used by Giovannini et al. and Lyons et al. The inset shows an example of a HOM interference dip (blue) with corresponding Fisher information distribution (red).
    Research

    Interferometry: Hong-Ou-Mandel quantum interferometry breaks nanometer measurement barrier

    Sept. 1, 2018
    Measurement of optical path thickness down to 1 nm is possible using Hong-Ou-Mandel interferometry, improving characterization of multilayer samples.