University of Utah created invisibility cloak for photonic chips

Dan Hixson / University of Utah College of Engineering

From the Harry Potter invisibility cloak to the Romulan concealment device that made the warship invisible in the Star Trek universe, the invisibility magic remains the result of fantasy science fiction writers and dreamers. American scientists decided to correct this annoying fact and created a “invisibility cloak” for the photon processor.

Professor of Electronics and Computer Engineering at the University of Utah Rajesh Menon and his team have developed a masking barrier for microscopic passive photon devices — standard photon computer chip blocks that operate on light pulses instead of electric current — to make chips smaller, faster and consuming much less energy in the future. .
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The advantage of photonic chips over modern silicon is the speed and consumption of less energy. Consequently, they emit less heat. In such a processor, you can increase the density of photon blocks, each of which will perform a specific function, by analogy with the billions of transistors in modern silicon chips. For example, one group of blocks of a microcircuit will perform calculations, another - data processing and so on.

However, there is a problem: if two photon blocks are too close to each other, they will not work, since a light leak between them will lead to "crosstalk", akin to radio interference. If you place them at a certain distance, the problem will be solved, but ultimately you will get a large processor.

So Menon and his team discovered that it is possible to put a special silicon nano-barrier between two photon blocks, which works like a “cloak” and “deceives” one, hiding from the other. “We used a principle similar to the invisibility cloak of Harry Potter. Light that hits one device is redirected back, simulating the absence of a “neighbor”. It looks like a barrier - it directs the light back to the source device. It is misleading that there is nothing on the other side, ”notes Rajesh Menon.

From this we can conclude that billions of photon blocks can be placed in one crystal. Since photonic chips use photons instead of electrons to transfer data, they can potentially consume 10 to 100 times less energy. Such processors should be used in data center servers similar to those owned by giant companies, such as Google and Facebook, since they consume a huge amount of electricity. According to a study conducted by the Lawrence Berkeley National Laboratory , only data centers consumed 70 billion kilowatt-hours in 2014, which is 1.8% of the total electricity consumption in the United States. Experts predict that by 2020, total consumption will increase by another 4%.

Today, photon processors are mainly used in high-end military technology. Menon suggests that the same chips will be used in data centers for several years. He also believes that its development will help solve global environmental problems: “Having traveled from electronics to photonics, we can make computers much more efficient and ultimately have a major impact on carbon emissions and energy consumption for all types of devices. Now many people are trying to solve this problem. ”

A year ago, a team of scientists led by Rajesh Menon developed an ultra-compact beam splitter - the smallest device ever created to divide light waves into two separate streams of information. Its size is only 2.4 micron. This is about 1/50 of the width of a human hair and close to the limit of the physical possibilities of miniaturizing such devices. Previously, the smallest device of this type was considered a beam splitter with a size of more than 100x100 microns.

This invention gave a definite impetus to the creation of fast photonic chips. Photonics can increase the power and speed of machines a million times: supercomputers, servers, data centers and specialized devices, autopilot systems in the car and technology to detect objects in UAVs. Ultimately, it should get to consumer devices - home computers and smartphones, as well as improve applications: from games to streaming video. The first silicon-based supercomputers are currently under development at companies such as Intel and IBM. They will use hybrid chips, partly consisting of traditional silicon elements, together with new - photon ones.

Russian scientists are also trying to keep up with their Western colleagues in the development of photonic devices. In 2015, researchers from Moscow State University as part of a group of foreign scientists created an optical pulse switch. A disk with a diameter of 250 nanometers is capable of operating for a time equivalent to femtoseconds (1 femtosecond is one millionth of one billionth of a second).

Scientific article published in the journal Nature Communications November 9, 2016
DOI: 10.1038 / ncomms13126