World’s Smallest Nanolaser a Breakthrough for Optical Computing

An international team of scientists has built what they say is the world’s smallest semiconductor laser, a breakthrough in photonic technology with possible applications ranging from computing to medicine, the University of Texas at Austin’s news site reported recently.

Established semiconductor technology uses metal-oxide transistor gates to effect computational functions via the movement of electrons. Nanolasers like the one developed by physicists from the U.S., Taiwan, and China are used in the emerging field of optical computing, which uses the movement of photons instead of electrons to perform computational logic.

Photonic technology, like quantum computing, is considered a possible future replacement for existing silicon-based transistors as scaling computer chip circuitry to smaller and smaller sizes begins to push against atomic boundaries and quantum effects.

Theoretically, computing could be done with light-based transistors rather than metal ones, but scientists have run up against obstacles like the “3D diffraction limit,” a barrier that Photonics describes as “limit[ing] the ability of optical instruments to distinguish between two objects separated by a distance of less than about half the wavelength of light used to image the specimen.”

The team led by UT physics professor Chih-Kang “Ken” Shih claims to have figured out a way around that barrier.

“We have developed a nanolaser device that operates well below the 3D diffraction limit. We believe our research could have a large impact on nanoscale technologies,” Shih told the college news site.

The device comprises a nanorod made of gallium nitride filled partially with indium gallium nitride placed on a 28-nanometer sheet of silicon covering a layer of silver film described as “smooth at the atomic level.”

Shih said the silver film, the product of 15 years of work at his UT lab, is instrumental to preventing the leakage of the “plasmons” that move big loads of data around his team’s proto-photonic transistor.

“Atomically smooth plasmonic structures are highly desirable building blocks for applications with low loss of data,” he told the college news site.

The tiny laser diode emits a green light “at low energy levels and cold temperatures,” according to the scientists, but it’s invisible to the naked eye.

For more from Damon, follow him on Twitter @dpoeter.

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