Researchers explore new chapter of physics

August 22, 2017 by Kayla Zacharias
Alexandra Boltasseva in her lab at Birck Nanotechnology Center. Credit: Purdue University photo/Alex Kumar

Interactions between light and matter are a fundamental unit of modern physics, but recently researchers have started to look beyond the standard textbook interactions.

Alexandra Boltasseva is a professor of electrical and computer engineering at Purdue University. For years, she's been working with optical metamaterials (artificially engineered containing nanostructures which give them unique visual properties) to create nanotweezers, metasurfaces and other tiny objects. Now, she's exploring an entirely new chapter of physics.

"If we look at a textbook and there's a chapter on how interacts with matter, it would go from how light interacts with transparent materials to how light interacts with reflective materials," Boltasseva said. "What we're going to study is this area between the two types."

When light propagates through , the light doesn't change very much, meaning it has a positive dielectric permittivity (also called epsilon). The opposite is true for , which expel light and have a negative permittivity (negative epsilon). Between positive and negative is an exotic, largely unexplored region referred to as Epsilon-Near-Zero (ENZ).

When light enters a medium whose permittivity is zero, observers will see the same light going in and coming out. It's almost like the light is tunneling from one side to the other without changing its properties – an unlikely phenomenon in physics.

"Since zero is so different from plus and minus one, we expect that many interesting things are happening there," Boltasseva said. "It brings completely news physics and insights into play."

Conventional ENZ media, such as metal, have naturally occurring zero crossings but often experience material loss (light absorption) at that point. To find a material that has a zero crossing but doesn't allow light absorption will be difficult, Boltasseva said.

The research team plans to experiment with both natural materials and new metamaterials, though natural materials are more likely to experience absorption. Adding a light-amplifying medium could counteract absorption, but it would be challenging. The group believes transparent conducting oxides and transition metal nitrides (newly developed materials that have a naturally occurring ENZ point in the visible and near infrared wavelength ranges, as well as tailorable optical properties) could help solve this problem.

Although Boltasseva believes this project's biggest impact will be on fundamental science, she thinks it will lead to new device applications as well.

"Ultrafast modulation is one of the big problems in optics. There's always a trade-off. You're either changing things really slowly at a large amplitude, or very fast but in a small range. I hope we can break this cycle," she said. "This could lead to a variety of ultrafast optical devices for communication and information technologies."

Explore further: Plasmonic metamaterials: From microscopes to invisibility cloaks

Related Stories

'Metasurfaces' to usher in new optical technologies

March 14, 2013

( —New optical technologies using "metasurfaces" capable of the ultra-efficient control of light are nearing commercialization, with potential applications including advanced solar cells, computers, telecommunications, ...

New 'metamaterial' practical for optical advances

May 15, 2012

( -- Researchers have taken a step toward overcoming a key obstacle in commercializing "hyperbolic metamaterials," structures that could bring optical advances including ultrapowerful microscopes, computers and solar ...

Recommended for you

Quantum internet goes hybrid

November 22, 2017

In a recent study published in Nature, ICFO researchers led by ICREA Prof. Hugues de Riedmatten report an elementary "hybrid" quantum network link and demonstrate photonic quantum communication between two distinct quantum ...

Enhancing the quantum sensing capabilities of diamond

November 22, 2017

Researchers have discovered that dense ensembles of quantum spins can be created in diamond with high resolution using an electron microscopes, paving the way for enhanced sensors and resources for quantum technologies.

Study shows how to get sprayed metal coatings to stick

November 21, 2017

When bonding two pieces of metal, either the metals must melt a bit where they meet or some molten metal must be introduced between the pieces. A solid bond then forms when the metal solidifies again. But researchers at MIT ...

Imaging technique unlocks the secrets of 17th century artists

November 21, 2017

The secrets of 17th century artists can now be revealed, thanks to 21st century signal processing. Using modern high-speed scanners and the advanced signal processing techniques, researchers at the Georgia Institute of Technology ...


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Aug 22, 2017
"When light enters a medium whose permittivity is zero, observers will see the same light going in and coming out. It's almost like the light is tunneling from one side to the other without changing its properties – an unlikely phenomenon in physics."

That's puzzling. Free space itself has permittivity, and it's pretty near zero:
8.85 x 10⁻⁻¹² farad per meter

Why would it be an 'unlikely' phenomenon? In fact, most of the light in the universe, transitioning from stars to space, has come by moving into a near-zero permittivity medium.
Aug 23, 2017
This comment has been removed by a moderator.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.