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Foam offers way to manipulate light

Foam offers way to manipulate light

Princeton researchers discovered that a form of foam that has long been researched by scientists may block specific wavelengths of light. This is recognized as a very desired feature for next-generation information technology that relies on light rather than electricity.

The researchers conducted extensive computer simulations of a structure known as a Weaire-Phelan foam, combining knowledge from materials science, chemistry, and physics. They discovered that some wavelengths of light could flow through while others were entirely reflected. This selective blockage, known as a photonic band gap, is analogous to the behavior of a semiconductor, which is the foundation of all contemporary electronics due to its ability to regulate the flow of electrons at extremely tiny scales.

While several examples of photonic band gaps have previously been demonstrated in other types of crystals, the researchers think that their latest discovery is the first in a foam, akin to the froth of soap bubbles or a draft beer. The Weaire-Phelan foam, in contrast to the chaotic froth of beer, is a finely structured arrangement with profound origins in mathematics and physics.

Phoamtonic networks in 3D obtained by thickening the edges of crystalline Weaire–Phelan foam (Left), Kelvin foam (Center), and C15 foam (Right)

The Weaire-Phelan foam’s roots may be traced back to 1887, when the Scottish scientist Lord Kelvin suggested a framework for the “ether,” a mysterious material considered to form a backdrop structure to all space at the time. Although the notion of the ether was already losing favor at the time, Kelvin’s suggested foam piqued the interest of mathematicians for a century since it looked to be the most effective method to fill space with interconnecting geometrical structures with the smallest possible surface area.

“You start out with a classical, beautiful problem in geometry, in mathematics, and now suddenly you have this material that opens up a photonic band gap.”

Weaire, who was not involved in the latest discovery, stated that it is part of a growing interest in the substance since he and Phelan found it. He believes the material’s potential new usage in optics derives from its isotropic, or lack of highly directed characteristics.

Klatt created a thorough series of computations that he ran on the supercomputing resources of the Princeton Institute for Computational Science and Engineering to demonstrate that the Weaire-Phelan foam displayed the light-controlling qualities they were looking for.

According to the experts, the new field of study, termed “phoamtonics,” opens up various opportunities for future development (a mashup of “foam” and “photonics”). With future research, the foam might be utilized to carry and modulate light in telecommunications. Currently, glass fibers carry a large portion of the data that traverses the internet. The light, however, gets transformed back to energy at its destination. Photonic band gap materials have the potential to direct light considerably more accurately than traditional fiber optic cables and to act as optical transistors that conduct calculations using light.

Phoamtonic designs yield sizeable 3D photonic band gaps, Michael A. Klatt, Paul J. Steinhardt, and Salvatore Torquato

Published: November 2019

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