White Hot Future for LEDs

MICHAEL D. WHEELER, michael.wheeler@photonics.com

Today’s LEDs are true workhorses. Prized for their lower energy consumption, physical robustness and faster switching, they’re found in applications as diverse as aviation lighting, lighted wall paper and automotive headlamps, and are powering the next generation of video displays and sensors.

Considered by many as a relatively “new” technology, some may find it surprising that the concept of electroluminescence, the means by which LEDs create light, was discovered more than a century ago.

British experimenter Henry Joseph Round of Marconi Labs was tasked with developing a new direction-finding system for marine transportation. Experimenting with a crystal of silicon carbide and a “cat’s whisker” detector, he observed how light was created when the crystal was exposed to electric current. His findings were published in the journal Electrical World in 1907, yet the discovery would go largely forgotten for decades.

Despite this inauspicious start, LEDs are transforming the world of photonics — and the world. Their use spans general illumination to UV-C water disinfection and near-IR emitters for night vision. Yet some LEDs rely on expensive (and environmentally unfriendly) rare earth materials such as cerium and yttrium. In this month’s print exclusive, Photonics Media Group Publisher Karen Newman explores exciting advances in the LED field, from new phosphors that achieve white light to luminescent rubber that, when combined with an LED of a certain wavelength, can also generate white light. Her article, “LED Materials Bring White Light and More,” (read article).

Also this month, Contributing Editor Hank Hogan’s “For Data Center Challenges, Silicon Photonics Solutions,” (read article), examines why the promising performance, energy-efficiency and potentially lower cost of silicon photonics make it an attractive alternative to copper for high-performance computing and data centers.

“New Frontiers in Nanophotonics: Diamond Optical Windows Show Promise for High-Power Lasers,” (read article), from Alex Muhr and Greg Mulligan of Element Six, covers recent advances in all-diamond optical windows that feature subwavelength surface structures as an alternative to conventional anti-reflective coatings.

Ehud Shafir, Shlomi Zilberman and Garry Berkovic of the Soreq Nuclear Research Center in Israel offer a unique approach for measuring rotating components like jet turbines using fiber Bragg gratings in “Sensing with Fiber Bragg Gratings in Rapidly Rotating Structures,” (read article).

Finally, don’t miss this month’s special feature “Collaboration Fuels Asia-Pacific Market Growth,” (read article), for a closer look at why Japan, China, Taiwan, Korea and other APAC countries are emerging as world leaders in the photonics industry.

Enjoy the issue.