A thin laser gets thinner

Researchers have created a microchip laser that fires an extraordinarily thin beam of high-intensity light. Because the beam can be as narrow as a few tens of nanometers across, it may prove useful for tasks such as writing close-packed data bits onto optical disks and identifying the chemicals making up nanoscale objects, its inventors say.

SHARPER IMAGE. Infrared emissions from a prototype microlaser reveal an intense beam (red in center spot) only 40 nanometers across. Some less focused radiation also appears as bright patches. E. Cubukcu et al./Applied Physics Letters

In the past, experimenters have shone microlaser beams through minute holes to create beams of nanoscale dimensions, notes electrical engineer Kenneth B. Crozier of Harvard University. However, the resulting beams were weak. To overcome this problem, he, Harvard physicist Federico Capasso, and their colleagues have interrupted a beam with a pair of close-spaced, rod-shaped gold patches. Fabricated right where the beam emerges from an infrared microlaser, the patches act jointly as a tiny antenna that focuses the laser light.

Crozier says that the narrowed beam is hundreds of times as intense as comparably thin beams shone through holes. The Harvard team describes its new device in the Aug. 28 Applied Physics Letters.

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