• Back Issues >
  • Laser Focus World >
  • Volume 53, Issue 10
  • Volume 53, Issue 10

    More content from Volume 53, Issue 10

    (Courtesy of Philips Photonics)
    FIGURE 1. A Philips Photonics high-power VCSEL array consists of many laser apertures in hexagonal packing and surrounded by gold contacts.
    Vertical-cavity surface-emitting laser arrays enable power scaling for lidar and other sensing applications.
    Oct. 12, 2017
    FIGURE 1. An optical time-domain spectroscopy unit (a) generates the ultrafast pump/probe signals while the near-field scanner unit (b) includes the terahertz emitter and near-field detector components, as well as translation stages for high-resolution field mapping; a sample or device under test is loaded to the near-field scanner unit.
    Replacing free-space optics with fiber-coupled, integrated components allows modular terahertz time-domain imaging systems to excel in solar and semiconductor wafer analysis.
    Oct. 12, 2017
    Terahertz-radiation outputs from a water film and from the air surrounding it can be separately measured. At the top is shown a situation in which the laser passes through the water film first and then focuses; here, a terahertz output characteristic of air is seen (similar to control setup at bottom of figure with no water film). Next, when the focus is moved to within the water film itself, the desired terahertz output from the water is seen. Finally, when the laser focuses first and then passes through the water, no terahertz output is seen because of absorption of terahertz radiation in the water.
    While terahertz radiation has been generated from solids, gases, and plasmas (the "fourth state" of matter) before, no one had created terahertz light from a liquid—until now....
    Oct. 12, 2017
    (Courtesy of Mark Montagut/ICFO)
    An illustration (a) shows CVD graphene transferred onto a single CMOS die (15.1 × 14.3 mm) with standard ROIC components in a 388 × 288 pixel array. The side view (b) shows the graphene layer and application of lead-sulfide (PbS) quantum dots and (c) their pixel architecture. On QD light absorption, an electron-hole pair is generated, the hole transfers to the graphene, and the electron is trapped in the QD; per the schematic (d), the balanced readout scheme is detailed into typical CMOS functional areas with a particular pixel pattern (e), as shown in the expanded areas (before QD application for clarity).
    A collaboration has integrated graphene with quantum-dot photodetectors on a CMOS platform to create a broadband imaging sensor.
    Oct. 12, 2017
    Experimental and simulated propagation losses of a mid-IR integrated multimode-interference (MMI) Mach-Zehnder interferometer are plotted for both TE (a) and TM (b) polarizations; the horizontal lines at -1.0 dB in both charts are just reference eye guides.
    Researchers have broken the 1-micron bandwidth barrier by creating an integrated mid-IR waveguide Mach-Zehnder interferometer that has a 3-micron spectral operating range.
    Oct. 12, 2017
    In a demonstration of the on-off switch effect of collimated polarized light imaging (CPLi), the blue arrow highlights a vertical structure (a), which appears whiter after rotating the polarizers (b). The opposite occurs at the oblique structure (green arrow) indicating nerve tissue. The CPLi stereo microscope that produced these images features a pair of adjustable collimation lenses that refract the light of 3 W LEDs on either side of the unit. It also provides a linear polarizer (on the outer rim of a polarization disk) that aligns perpendicularly to an inner linear polarizer.
    But polarized light is showing the way to real-time, noninvasive visualization of nerve tissue.
    Oct. 12, 2017
    (Courtesy of AdlOptica)
    Multifocus optics produce many different focal points-four (a) and seven (b) shown here—and can be manually adjusted to deliver a desired materials processing effect such as a more longitudinal, uniform beam profile by distributing the energy from four focal spots (c) as compared to a single focus (d).
    Whether cutting, welding, or patterning various materials using a laser, the materials-processing end result correlates directly with the size, shape, and intensity of the laser...
    Oct. 12, 2017
    Content Dam Lfw Print Articles 2017 10 1710lfw Nb F3
    Researchers have come up with a way to create a bulk nonreciprocal mirror that, at least in theory, can have a 50 dB isolation and a very high reflection.
    Oct. 12, 2017
    Content Dam Lfw Print Articles 2017 10 1710lfw Nb F4
    An infrared sensor based on a plasmonically enhanced micromechanical photoswitch remains dormant with near-zero power consumption until awakened by an external trigger or stimulus...
    Oct. 12, 2017
    Amorphous silicon, with its disorder and thus abundant localized states, would be a good active material for a cycling excitation process-based low-light detector.
    Oct. 12, 2017
    Content Dam Lfw Print Articles 2017 10 1710lfw Nb F2
    An optothermophoretic assembly method uses an ionic surfactant to manipulate and assemble most any colloidal matter using a light-controlled temperature field.
    Oct. 12, 2017
    Content Dam Lfw Print Articles 2017 10 1710lfw Nb F1
    Physicists have theoretically determined that ultrafast laser pulses can, when focused, be made to travel at different velocities when propagating in a vacuum.
    Oct. 12, 2017
    Conard Holton2
    The great thing about both the business and technology sides of photonics is that you get a lot of "wows."
    Oct. 12, 2017