A telecommunications-compatible IR beam is coupled to a whispering gallery
resonator through a diamond prism, and the generated near-infrared, visible
and ultraviolet light are collected by a multimode fiber. GRIN = gradient index.
Courtesy of Mona Jarrahi, University of Michigan.
the input beam, and one-quarter of the original wavelength.
The work appeared online in Optics Express ( http://dx.doi.org/
UV light sources have applications in crisper medical imaging,
chemical detection and finer lithography for more sophisticated
integrated circuits and greater computer memory capacity.
“Our results can also transform many nonlinear optical studies
“Egg crate” structure optimizes
which are currently only possible using femtosecond pulses to
offer the required high pump power levels,” Jarrahi said. “For
example, and despite many challenges on the way, extreme
light-matter interactions may be extended to be continuous in
time. Also, imaging crystals and molecular states with subatomic-
scale resolution will benefit from a continuous-in-time source.”
The researchers hope to extend their work to generate light
beams at other wavelengths that are difficult to achieve through
standard solid-state laser sources, such as terahertz wavelengths
and extreme UV.
CAMBRIDGE, Mass. – A new quantum-dot (QD) LED “egg
crate” design turns formerly troublesome ligand molecules into
a critical element of a more versatile quantum-dot LED structure for applications in lighting, lasers and displays.
Ligands – organic molecules that dangle from quantum dots –
are essential to quantum dot growth but can interfere with current
conduction and cause functional problems later on. Researchers at
Harvard School of Engineering and Applied Sciences have discovered an alternative that uses ligands to build a more versatile
single-layer, egg-cratelike structure that better controls the flow
of electric current – optimizing the QD-LED’s performance.
QDs are grown in a solution that can be deposited onto the
surface of an electrode, but because the ligands are attached, the
process gets complicated, according to the researchers. The core
of the QD is a perfect lattice of semiconductor material, but its
exterior is a lot more complicated. The dots are coated with lig-