Cloaking Devices and the Hunt for Faster Computing

By Rita Waimer

For many, the idea of a cloaking device belongs entirely to science fiction or a distant, distant future. But University of Utah professor Rajesh Menon’s microscopic work tells a different story.

In November 2016, Menon, doctoral student Bing Shen and senior optical engineer Randy Polson published a paper in Nature Communications detailing how they developed a cloaking device that hides microscopic photonic integrated devices from one another inside photonic computer chips.

The Power of Light

Photonic computer chips use light photons instead of electrons to transfer and process data. They’re faster than silicon chips, yet they could consume 10 to 100 times less energy. Photonic chips are already being used in high-end military equipment, and their reduced power consumption could be hugely beneficial to data centers, which are expected to account for 4 percent of all electricity usage in the U.S. by 2020.

The struggle with photonic chips is that the devices within them must be spaced apart for the chip to work properly. If they’re too close together, leaking light will spread from one device to another and cause interference. The spacing requirement is fine for simple chips, but forces more powerful chips to become larger, limiting where they can be used. Menon’s cloak aims to eliminate this spacing requirement, allowing photonic devices to be packed more densely together and making photonic chips more capable than ever before.

Invisibility for the Future

Menon and his team placed nanopatterned silicon-based barriers between the devices, preventing them from “seeing” one another. Any light that leaks out of one device is redirected back to it, fooling the device into thinking there’s nothing on the other side of the barrier. Other researchers have demonstrated similar cloaks before, but Menon’s cloak occupies a much smaller footprint. Moreover, it’s applicable to various integrated photonic components.

It’s an exciting development for silicon photonics, which are gaining more and more interest from influential companies like Facebook and Google. The chips are already being tapped for use in emerging technologies like self-driving cars, and as they mature they’ll become more affordable and inevitably be used in consumer devices. Particularly, they’ll bring longer battery life to smartphones, smartwatches and other small devices that have limited space for batteries — something users have been wanting for years.