A monumental breakthrough achieved by a world-spanning group of engineering professors has led to the creation of photonic computer chips that can propagate light without slowing it down and without changing phase. In the words of one of the researchers, Serdar Kocaman, “the light disperses through the material as if the entire space is missing.”

To create this “invisible” chip, the scientists had to create photonic crystals that have a negative refractive index. All natural materials in the known universe have a positive refractive index — which means that they alter the trajectory of any electromagnetic radiation that travels through it, including light. This creates one of the biggest problems in optical switching and transmissions: as light bounces down a piece of fiber or inside a computer chip, refraction alters both the speed of light (the signal) and the phase. With this new chip, light enters the photonic integrated circuit on one side, bounces along a cascade of positive-index reflectors and negative-index metameterial photonic crystals, and emerges from the other side with zero refractive index and perfect optical phase.

A metamaterial is an artificial material that is engineered to have properties that can’t be found in nature — thus, because every natural material has a positive refractive index, the negative-index photonic crystals used in the new chip are a metamaterial. Photonic crystals are nanostructures that manipulate photons in much the same way that semiconductors affect the motion of electrons. The photonic chips created by this breakthrough, then, contain a nanofabricated superlattice of alternating negative-index metamaterial photonic crystals and positive-index dielectric media.

The implications and potential ramifications of this new technology are rather exciting. It will first have an impact on the biggest user of photonics: telecommunications. Next, because wireless signals are electromagnetic radiation, just like light, this new technology could be used to create highly directional antennae, and even faster wireless networks. Beyond that, you’re then looking at computer chips that actually process data using light.

Finally, according to Chee Wei Wong, the lead researcher, this breakthrough might lead us towards a cloak of invisibility. “We can now control the flow of light, the fastest thing known to us. This can … [potentially lead to] an approach to cloak or hide objects, at least in the small-scale.”

Read more at Columbia Engineering or Nature Photonics