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15 COVER STORY
Mapping the momentum
distributions of electrons
released by atoms exposed to intense ultrashort laser pulses using
laser-induced electron
diffraction (LIED) yields a
series of images at different wavelengths that reveal the nuclear motion of
a molecule.
37 Light-emitting Diodes
GaN-on-GaN platform removes
cost/performance tradeoffs in
LED lighting
Full-visible-spectrum LED technology
made practical by GaN-on-GaN has
eliminated the truncated spectra,
poor color rendering capability, and
fundamental illumination problems
associated with LEDs using primary
blue emitters. Mike Krames
41 Photonics Applied: Robotics
Microrobots slide, crawl, and
swarm into new applications
Whether diagnosing poor oxygen
supply in eyes, sensing diseases in
the GI tract, or cleaning up dangerous
situations, microbots are becoming
more mobile, better communicators,
and more precise. Gail Overton
47 Laser Diode and VCSEL Test
High-throughput DC
production test techniques
for laser-diode modules and
VCSELs
High-speed DC test instruments and
techniques for testing of laser diodes
and VCSELs enable manufacturers to
carry out complicated test sequences
at high throughput. The resulting
100% testing cuts down on costs of
scrapping parts. Dale Cigoy
51 Photonic Frontiers: Optical Antennas
Optical antennas concentrate
light and direct beams
Like their radio-frequency counterparts,
optical antennas can collect energy
on subwavelength scales, enhancing
absorption for a range of applications
such as heating, spectroscopic probing,
and light detection. Jeff Hecht
56 High-speed Imaging
Laser illumination reveals
high-brightness processes
High-brightness events such as arc
welding and explosions are normally
difficult to image due to obscuring
glare, but pulsed laser illuminators
cut through the glare to reveal the
processes’ inner workings. Tim Stephens
59 Spectroscopy
Cancer detection using
Stokes shift spectroscopy
Research demonstrates that—
and explains why—Stokes shift
spectroscopy (S3) is superior to
other spectroscopic techniques for
recognizing the spectral fingerprints
of biomolecules’ absorption and
fluorescence spectra in complex
mixtures. Yang Pu, Wuabo Wang, Yuanlong
Yang, and Robert R. Alfano
Coming in
October
Zinc oxide
detectors move
further into
the UV
Currently, solid-state
ultraviolet (UV) emitters
and detectors are being
developed as more
compact, robust, and
cheaper alternatives to
incumbent technologies.
To that end, recent
breakthroughs in alloying
zinc oxide (ZnO) with
magnesium (Mg) could
offer an alternative route
to deep-UV emitters/
detectors with reduced
lattice and efficiency
issues.
