Laser pulse faster than light12/24/2023 ![]() For instance, alterations in an incoming light pulse could increase or decrease the product of a chemical reaction. The rapid, finely tuned changes can also be used to study and change the outcome of chemical or biological processes. When a device known as a polarizer is attached to the back of the silicon, the change in polarization can be translated to a corresponding change in amplitude.Īltering the phase, amplitude or polarization of a light wave in a highly controlled manner can be used to encode information. The size of the nanopillars determines the amount by which the phase changes, whereas the orientation of the nanopillars changes the light wave’s polarization. When a light wave travels through a set of the silicon nanopillars, the wave slows down compared with its speed in air and its phase is delayed-the moment when the wave reaches its next peak is slightly later than the time at which the wave would have reached its next peak in air. “To achieve this, we used carefully designed sets of silicon nanopillars, one for each constituent color in the pulse, and an integrated polarizer fabricated on the back of the device.” “We figured out how to independently and simultaneously manipulate the phase and amplitude of each frequency component of an ultrafast laser pulse,” said Amit Agrawal, of NIST and the NanoCenter. If you’re standing in the ocean, the frequency of the wave is how often the peaks or troughs travel past you, the amplitude is the height of the waves (trough to peak), and the phase is where you are relative to the peaks and troughs. ![]() These properties include the amplitude, phase and polarization of the wave.Ī light wave, a set of oscillating electric and magnetic fields oriented at right angles to each other, has peaks and troughs similar to an ocean wave. By carefully designing the shape, size, density and distribution of the nanopillars, multiple properties of each light pulse can now be tailored simultaneously and independently with nanoscale precision. The flat, ultrathin device is an example of a metasurface, which is used to change the properties of a light wave traveling through it. By etching away the silicon surrounding each square, the team created millions of tiny pillars, which played a key role in the light sculpting technique. They first deposited a layer of ultrathin silicon on glass, just a few hundred nanometers (billionths of a meter) thick, and then covered an array of millions of tiny squares of the silicon with a protective material. Now researchers at the National Institute of Standards and Technology (NIST) and the University of Maryland’s NanoCenter in College Park have developed a novel and compact method of sculpting light.
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