Metamaterial with Zero Refractive Index Developed

All materials that appear in nature have a positive refractive index, but a team of experts recently manged to produce a new device, that has an index of refraction of zero. This is the first time that such a material is produced using nanotechnology.

Columbia Engineering School investigators led the collaborative research effort, which involved using the most advanced nanomanufacturing technologies. What the team had to do was basically develop a negative refraction index from scratch.

The end goal was showing that electromagnetic waves – in this case light – can travel through a material from point A to point B without accumulating any phase. This artificial medium has no behavior, which is to say that it acts as if it's completely missing in space.

An innovation such as this one ensures that scientists always remain fully in control of light dispersion in the materials they create. The new study marks the first time simultaneous phase and zero-index observations are made at infrared wavelengths.

In order to achieve this performance, experts used advanced manufacturing methods to produce nanoscale structure that would produce a negative refraction index in the new material. They then alternated these layers with ones that had positive refraction indexes.

As light traveled through the material, the total sum of refraction was zero. Details of the research effort appear in the July 10 online issue of the top journal Nature Photonics, Science Blog reports.

“We’re very excited about this. We’ve engineered and observed a metamaterial with zero refractive index. What we’ve seen is that the light disperses through the material as if the entire space is missing,” explains Serdar Kocaman.

“The oscillatory phase of the electromagnetic wave doesn’t even advance such as in a vacuum – this is what we term a zero-phase delay,” adds the expert, who is a PhD candidate in electrical engineering at Columbia Engineering School.

He and associate professor of mechanical engineering Chee Wei Wong led the new study. Colleagues from the University College London, the US Department of Energy's (DOE ) Brookhaven National Laboratory (BNL), and the Institute of Microelectronics of Singapore also collaborated in the study.

“Phase control of photons is really important. This is a big step forward in figuring out how to carry information on photonic chips without losing control of the phase of the light,” Wong explains.

“We can now control the flow of light, the fastest thing known to us. This can enable self-focusing light beams, highly directive antennas, and even potentially an approach to cloak or hide objects, at least in the small-scale or a narrow band of frequencies currently,” he concludes.