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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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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