Optical wireless may be the answer to dropped calls, and more

A demonstration set-up in Mohsen Kavehrad's lab creates partially coherent visible (red) light. This type of light performs better through the atmosphere than pure coherent light, an important consideration for outdoor optical wireless applications. Anyone who has tried to make a cell phone call from a crowded football stadium has had a taste of what engineers call spectrum crunch. Can you hear me now? Uh, no, actually. Not so much. The looming problem, and the reason for all those dropped calls, is that there's not enough bandwidth to accommodate the exploding use of wireless mobile applications. "The first wireless mobile users in this country were police and taxicabs talking to dispatchers," explains Mohsen Kavehrad, W.L. Weiss Chair Professor of Electrical Engineering at Penn State.