Sagar Jethani, Head of content, Element14
Recent innovations in LED technology are blurring the lines between lighting and
software. For example, instead of just installing
special “grow lights” in a greenhouse, you can
now run alongside it a code which will illuminate
your plants with the precise color temperature needed to
stimulate growth for a particular species. Not to mention
there is now technology that can intelligently phase the light’s
intensity to mimic natural solar patterns, among other more
advanced software-driven LED applications.
Smart LEDs are also being used as a means of
communication. Philips’ line of HUE products is a prime
example of this. The Philips HUE can adjust the intensity of
your light to convey specific information – like whether or not
your train is running late or whether or not you should carry
an umbrella because rain is in the forecast. The marriage of
LEDs and intelligent software is unlocking a myriad of new
applications daily that are challenging conventional norms
around lighting design.
The third “next big thing” in LEDs is UV. Ultraviolet LEDs
are becoming more and more powerful and are now being used
in a variety of innovative applications – from curing resins and
killing germs found on food to detecting counterfeit currency.
High-power UV LEDs, like software applications and smart
LEDs, are forcing engineers and consumers alike to rethink
how lighting can make day-to-day tasks easier, more intelligent
and more intuitive.
Dan Herrmann, CAE Manager, Synopsys Optical
There continues to be extensive research into how to improve LED performance, such as
how to enhance light extraction efficiency to
improve LED efficacy, package- and module-level
beam shaping to drive down size and cost for LED lighting
applications at the system level, and package-to-system-level
color tuning to improve LED color consistency and lower cost.
LED chip and package engineers are now incorporating
sophisticated techniques into LED die and package designs,
such as patterned substrates, polarization-sensitive gratings, back
reflectors, surface textures, photonic lattices, and phosphor
down-conversion. LED technologies, especially those with
patterned or textured surfaces, contain geometric features
that vary in size over orders of magnitude – ranging from large
photonic elements to nanostructured surfaces. Because of the
complexity of these LED designs, it is increasingly necessary
for design and simulation software tools to use a variety of
numerical techniques to completely analyze and improve LED
die, package and module performance. A mixed-level simulation
approach in optical design software is emerging as an effective
way to develop these LED technologies.
Rigorous electromagnetic (EM) wave-based tools, rather
than geometric optics ray tracing techniques, must be used
to completely characterize scattering from nanostructured
LED surfaces. The characteristics predicted using EM wave-
calculations can then be incorporated into geometric ray
tracing software to obtain overall LED die or package-level
performance. As an example, Synopsys’ Optical Solutions
Group has recently developed an approach using either the
RSoft™ DiffractMOD™ or Full WAVE™ tools to generate
bidirectional scattering distribution function (BSDF)
information for a patterned LED surface with feature sizes
near the scale of the wavelength of emitted LED light. This
BSDF information, which contains full polarization data, can
then be incorporated into a geometric ray tracing tool such as
Light Tools®, permitting full analysis of the LED chip, package
and module performance. This multi-simulation approach to
LED design provides comprehensive, accurate modeling that is
not possible through other methods, and can be used in a wide
variety of applications aside from LEDs, including OLEDs, color
filters, and photovoltaics.
This approach of using EM wave calculations with geometric
raytrace simulations is very likely to increase in the future for
developing new LED (and OLED) technologies.
David J. Donovan, VP Sales, America’s, Plessey
The ubiquitous LED is poised to become much more than a passive p-n junction
that emits light. Today’s LEDs are built on
various substrate materials, and together with advances in
semiconductor physics, drive higher efficacies and efficiencies
while lowering costs.
However, the real long term value is not found in honing
these metrics, but in the next big thing in LEDs; silicon based
monolithic integrated lighting solutions.
Lighting systems are made up of numerous autonomous
electro-mechanical components, and as such are subject
to the vagary and inefficiencies of the marketplace. The
next generation of LEDs will be part of a Smart Lighting
and Control system that integrates many of the electronic
components. The most cost effective approaches to
implementing these systems will take advantage of
incumbent silicon technologies to incorporate various Smart
Lighting features such as environment sensing, control and
communications, power optimization, dynamic light intensity
and energy savings.
Silicon wafer fabs are ideal for fostering this next big thing as
mature foundry operations can integrate passive functions such
as photo sensing diodes and temperature sensors together with
the LED onto a silicon sub-mount. Adding Chip Scale Optics
(CSO), Chip Scale Packaging (CSP) and/or Wafer Scale
Packaging (WSP) makes the silicon based lighting solutions
more cost effective.
In addition, the same silicon wafer fabs can produce the
ancillary building blocks that make up a lighting system such as
the power driver, control system and analog front ends.