In recent years, light-emitting diodes (LEDs) have begun to change the way we see the world. However, until now, the emitted light from LEDs has been unpolarized. Now a Rensselaer Polytechnic Institute student has developed a polarized LED that brings benefits to existing applications and also opens the door to some new ones.

The development was spearheaded by Martin Schubert, a doctoral student in electrical, computer, and systems engineering at Rensselaer Polytechnic Institute in Troy, NY. Schubert's innovation has earned him the $30,000 Lemelson-Rensselaer Student Prize. The prize, which was first given in 2007, is awarded to a Rensselaer senior or graduate student who has created or improved a product or process, applied a technology in a new way, or otherwise demonstrated remarkable inventiveness.

Schubert's group is collaborating with Samsung and New York State who are both currently funding his project.

If you place a polarizer in front of an unpolarized LED, half the light would be polarized but the other half would be unpolarized — and wasted. A polarized LED provides approximately 50% more light, or looking at it from the standpoint of efficiency a polarized LED delivers the same amount of light as an unpolarized LED, but a with one-third less energy. The focused light emitted by a polarized LED produce images on the display that are more colorful, vibrant, and lifelike, with no motion artifacts.

Polarized LEDs are well suited for established applications such as back lighting LEDs in computer displays and aircraft cockpits, as well as new opportunities in machine vision in which higher resolution is essential and in free-space optical communications where polarization would reduce the noise level enabling the data rates to be raised.

All that would be required to use polarized LEDs in existing designs is to reconfigure the reflector geometry.

Schubert first discovered that traditional LEDs actually do produce polarized light, but that they fail to capitalize on the light's polarization. Armed with this information, he devised an optics setup around the LED chip to enhance the polarization, creating the first polarized LED.

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