Many materials can polarize light, though, and that ability alone is not especially useful. What makes black phosphorous special, Atwater says, is that it is also a semiconductor, a material that conducts electricity better than an insulator, like glass, but not as well as a metal like copper. The silicon in microchips is an example of a semiconductor. And just as how tiny structures built from silicon can control the flow of electricity in a microchip, structures built from black phosphorous can control the polarization of light as an electric signal is applied to them.

“These tiny structures are doing this polarization conversion,” Atwater says, “so now I can make something that’s very thin and tunable, and at the nanometer scale. I could make an array of these little elements, each of which can convert the polarization into a different reflected polarization state.”

The liquid crystal display (LCD) technology found in phone screens and TVs already has some of those abilities, but black phosphorous tech has the potential to leap far ahead of it. The “pixels” of a black phosphorous array could be 20 times smaller than those in LCDs, yet respond to inputs a million times faster.

Such speeds are not necessary for watching a movie or reading an article online, but they could revolutionize telecommunications, Atwater says. The fiber-optic cable through which light signals are sent in telecommunications devices can transmit only so many signals before they begin to interfere with and overwhelm each other, garbling them (picture trying to hear what a friend is saying in a crowded and loud bar). But a telecommunications device based on thin layers of black phosphorous could tune the polarization of each signal so that none interfere with each other. This would allow a fiber-optic cable to carry much more data than it does now.

Atwater says the technology could also open the door to a light-based replacement for Wi-Fi, something researchers in the field refer to as Li-Fi.

“Increasingly, we’re going to be looking at light-wave communications in free space,” he says. “Lighting like this very cool-looking lamp above my desk doesn’t carry any communication signal. It just provides light. But there’s no reason that you couldn’t sit in a future Starbucks and have your laptop taking a light signal for its wireless communication rather than a radio signal. It’s not quite here yet, but when it gets here, it will be at least a hundred times faster than Wi-Fi.”

The paper describing the work is titled, “Broadband electro-optic polarization conversion with atomically thin black phosphorus.” The lead author is Souvik Biswas, graduate student in applied physics. Other co-authors are Meir Y. Grajower, postdoctoral scholar research associate in applied physics and materials science, and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan.

“These are exciting times for new materials discovery that can shape the future of photonic devices, and we have barely scratched the surface,” Biswas says. “It would be gratifying if some day you could buy a commercial product constructed out of such atomically thin materials, and that day might not be very far.”