Low-Power Laser Could Speed CPUs

The polariton laser now runs on electricity, operates at room temperature, and could be key to on-chip optical interconnects

3 min read
Low-Power Laser Could Speed CPUs
Reflected Glory: University of Michigan engineers built a polariton laser (triangle) that runs on electricity and operates at room temperature. The key was to lower the resistance of the device’s reflectors.
Image: University of Michigan

Lasers have largely replaced the copper wiring of old to speedily stream bits among servers in large data centers. Engineers have long dreamed that they could use lasers to do the same within the servers’ data-congested processors, too. One problem standing in their way is that even the most efficient lasers need an awful lot of current before they light up. But a new kind of device, the polariton laser, could light the way using merely a trickle of electrons. Until recently, however, the device has worked only in an impractical environment.

Now, researchers at the University of Michigan have built the first polariton laser that both runs on electricity and operates at room temperature. It emits coherent light when provided with a current of only 169 amperes per square centimeter. A similar structure operating as an ordinary laser would take more than 250 times as much current, and even the best gallium nitride laser, enhanced with quantum dots, requires at least 1000 A/cm2 before it starts lasing.

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The Ultimate Transistor Timeline

The transistor’s amazing evolution from point contacts to quantum tunnels

1 min read
A chart showing the timeline of when a transistor was invented and when it was commercialized.

Even as the initial sales receipts for the first transistors to hit the market were being tallied up in 1948, the next generation of transistors had already been invented (see “The First Transistor and How it Worked.”) Since then, engineers have reinvented the transistor over and over again, raiding condensed-matter physics for anything that might offer even the possibility of turning a small signal into a larger one.

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