Metamaterial Polarizing Filter Brightens LCDs, Photos

Polarizers are vital for LCDs and photography, but they waste energy by blocking enormous amounts of light. A new filter skirts this obstacle.

A team from the University of Utah developed the polarizing filter, which allows more light in to increase the lifespan of a display’s single battery charge and helps cameras and imagers function better in dim light.

The filter was created by etching a silicon wafer with nanoscale pillars and holes using a focused gallium-ion beam. The multilevel metamaterial linear polarizer rotates light with polarization perpendicular to its principal axis by 90°, the researchers wrote in the study.

Professor Dr. Rajesh Menon holds a piece of silicon etched with microscopic pillars and holes to create a polarizing filter. Courtesy of the University of Utah.

They tested the filter using a 20 × 20-µm polarizer with only IR light. Such light filtering can perform the same function as a standard polarizer, but it allows almost 30 percent more light to pass through.

“If one can increase that energy efficiency, that is a huge increase on the battery life of your display,” said professor Dr. Rajesh Menon. “Or you can make your display brighter.”

The filter also brightens photographs by converting much of the light that would typically be reflected or absorbed into a desired polarized state.

“When you take a picture and put the polarized filter on, you are trying to get rid of glare,” Menon said. “But most polarizers will eliminate anywhere from 60 to 70 percent of the light.”

In a study, about 74 percent of the light was able to pass through.

“Conventional polarizers operate by rejecting undesired polarization, which limits their transmission efficiency to much less than 50 percent when illuminated by unpolarized light,” the researchers wrote.

The filter could be commercialized within the next five to 10 years, Menon said, for photography, display and imaging applications.

The work was funded by NASA, the U.S. Department of Energy and the Utah Science Technology and Research Economic Development Initiative. The research was published in Optica (doi: 10.1364/optica.1.000356).

For more information, visit www.utah.edu.