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Nanolaser Heats Up

Spaser nanolasers can now operate at room temperature

2 min read
Nanolaser Heats Up

Nanolasers just got a little toastier. No, we're not talking about the world's tiniest death rays. The surface plasmon lasers, or "spasers," that IEEE Spectrum described last year can generate visible light in a space only 5 nanometers wide. They seemed a promising step towards the age of optical computing, but the little guys had a serious flaw: The devices, which stimulate oscillating electrons near a metal's surface with electromagnetic waves, needed a frigid 10 Kelvin environment to keep the light from leaking out. In a paper, published on Sunday in Nature Materials, a University of California, Berkeley team reports that they've modified the laser so that it can now operate at room temperature.

According to a university press release, the research team led by Xiang Zhang, a mechanical engineering professor at UC, Berkeley, found the solution by redesigning the lasers to work a bit like whispering galleries. These often dome-shaped spaces (such as the one in New York City's Grand Central Station, pictured below) allow two people to utter secret messages across a room, as the sound waves reflect off the ceiling.

For their ceiling, Zhang's team used a 45 nanometer-thick cadmium sulfide patch--which captured the light in a 5-nanometer magnesium fluoride gap between a silver base and the cadmium sulfide. 

The press release says the Berkeley scientists could then confine the light to 20 nanometers and forgo the cryogenics. According to Zhang, a room-temperature spaser nanolaser could lead to single-molecule biodetectors, photonic circuits, and high-speed optical communication systems. Renmin Ma, also at UC, Berkeley, adds:

"The present square plasmon cavities not only can serve as compact light sources, but also can be the key components of other functional building-blocks in integrated circuits..."

Images:  Renmin Ma and Rupert Oulton, UC, Berkeley / flickr: nickgraywfu

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A photo of a birthday cake with 75 written on it.
Lisa Sheehan
LightGreen

Seventy-five years is a long time. It’s so long that most of us don’t remember a time before the transistor, and long enough for many engineers to have devoted entire careers to its use and development. In honor of this most important of technological achievements, this issue’s package of articles explores the transistor’s historical journey and potential future.

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