Engineering 101

Control light with three-atoms thick material

A new breakthrough uses a specialized material a mere three atoms thick to more precisely control light than previously possible. The work was conducted in the lab of Harry Atwater, and the results appear in a paper published in the October 22 issue of Science. In the paper, Atwater and his co-authors describe how they used three layers of phosphorous atoms to create a material for polarizing light that is tunable, precise, and extremely thin.

Polarization allows light to be controlled in specific ways and light waves can be polarized at any angle. The areas where polarized light is blocked appear dark, while areas where the light is not blocked appear light.

The material is constructed from so-called black phosphorous, similar to graphite, or graphene, forms of carbon that consist of single-atom-thick layers. However, black phosphorous’s layers are ribbed, like corrugated cardboard. That crystal structure gives black phosphorus significantly anisotropic optical properties.

When polarized light is oriented across the corrugations, it interacts with the material differently than when it is oriented along the corrugations. Black phosphorous is also a semiconductor. The “pixels” of a black phosphorous array could be 20 times smaller than those in LCDs yet respond to inputs a million times faster. 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.

Original Release: Eureka Alert

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