Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

But in order to tune to different frequencies, either the capacitance or inductance needs to change. So, as a first attempt, Chen adds silicon to the metal squares to change the capacitance of the structure. Silicon is responsive to light, so when Chen shines a near-infrared laser onto the strips, their capacitance changes, which selects a specific frequency from the incoming terahertz light. By adjusting the power from the infrared laser, Chen was able to tune in to specific frequencies from 850 gigahertz to 1.06 terahertz.

While Chen’s recent work is important for tuning across a range of terahertz frequencies, bringing it closer to a practical application, his approach could also be used for other frequencies. “What’s interesting here is, the way they’ve chosen to achieve [tunability] is versatile,” he says. The same approach of adding silicon strips could be used for devices at different wavelengths, including microwave and optical frequencies. While there are already devices that can tune across these, a tunable metamaterial is of interest to researchers for several reasons. Metamaterials are able to perform bizarre feats: lenses made of metamaterials can focus light tighter than conventional lenses can, and metamaterials have even been used to make a rudimentary cloaking device. A tunable metamaterial for many different wavelengths could expand the potential of these early applications.

Chen says that his next step is to tune the filter using electrical current instead of optical laser pulses. While it was more straightforward to change silicon’s properties by shining light on it, it’s ultimately more practical to use an electric current in an imaging system or wireless device.

2 comments. Share your thoughts »

Credit: Hou-Tong Chen, LANL

Tagged: Computing, imaging, wireless, metamaterials, invisibility, terahertz

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me