Polarization could be helpful as a result of it permits gentle to be managed in particular methods. For instance, the lenses in your sun shades block glare (gentle usually turns into polarized when it displays off a floor, just like the window of a automobile). The display of a desk calculator creates legible numbers by polarizing gentle and blocking it in areas. These areas the place the polarized gentle is blocked seem darkish, whereas areas the place the sunshine shouldn’t be blocked seem gentle.
Within the paper, Atwater and his co-authors describe how they used three layers of phosphorous atoms to create a cloth for polarizing gentle that’s tunable, exact, and intensely skinny.
The fabric is constructed from so-called black phosphorous, which is analogous in some ways to graphite, or graphene, types of carbon that include single-atom-thick layers. However whereas the layers of graphene are completely flat, black phosphorous’s layers are ribbed, like the feel of a pair of corduroy pants or corrugated cardboard. (Phosphorus additionally is available in purple, white, and violet types, distinct due to the association of the atoms inside it.)
That crystal construction, Atwater says, makes the black phosphorus have considerably anisotropic optical properties. “Anisotropy means is that it’s angle dependent,” he explains. “In a cloth like graphene, gentle is absorbed and mirrored equally irrespective of the angle at which it’s polarized. Black phosphorus could be very completely different within the sense that if the polarization of sunshine is aligned alongside the corrugations, it has a really completely different response than if it’s aligned perpendicular to the corrugations.”
When polarized gentle is oriented throughout the corrugations in black phosphorous, it interacts with the fabric in another way than when it’s oriented alongside the corrugations—form of like how it’s simpler to rub your hand alongside the ribs in corduroy than it’s to rub your hand throughout them.