Scientists demonstrate highly directional semiconduc...( CAMBRIDGE Mass. July 28 2008 Appli...)

CAMBRIDGE, Mass. July 28, 2008 Applied scientists at Harvard University in collaboration with researchers from Hamamatsu Photonics in Hamamatsu City, Japan, have demonstrated, for the first time, highly directional semiconductor lasers with a much smaller beam divergence than conventional ones. The innovation opens the door to a wide range of applications in photonics and communications. Harvard University has also filed a broad patent on the invention.

Spearheaded by graduate student Nanfang Yu and Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, all of Harvard's School of Engineering and Applied Sciences (SEAS), and by a team at Hamamatsu Photonics headed by Dr. Hirofumi Kan, General Manager of the Laser Group, the findings were published online in the July 28th issue of Nature Photonics and will appear in the September print issue.

"Our innovation is applicable to edge-emitting as well as surface-emitting semiconductor lasers operating at any wavelengthall the way from visible to telecom ones and beyond," said Capasso. "It is an important first step towards beam engineering of lasers with unprecedented flexibility, tailored for specific applications. In the future, we envision being able to achieve total control of the spatial emission pattern of semiconductor lasers such as a fully collimated beam, small divergence beams in multiple directions, and beams that can be steered over a wide angle."

While semiconductor lasers are widely used in everyday products such as communication devices, optical recording technologies, and laser printers, they suffer from poor directionality. Divergent beams from semiconductor lasers are focused or collimated with lenses that typically require meticulous optical alignmentand in some cases bulky optics.

To get around such conventional limitations, the researchers sculpted a metallic structure,
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