Nano antenna increases the intensity of light by a factor of 1,000

Sensors and non-linear optics could get a major boost.
Written by Boonsri Dickinson, Contributing Editor

The antenna issue on the iPhone 4 turned out to be an embarrassing issue for Apple. But have you ever thought about how the antennas in our phones and our TVs actually work?

An antenna takes in aerial signal around it. An optical antenna operates in a similar way, by taking in light into a small point. Based on that same principle, physicists have figured out how to increase the intensity of light going through the antenna.

However, when you shine light through a small space, the rules governing it change. That's why Rice researchers are combining optics and electrical measurement to get promising results.

"The reason we're studying these enhanced fields is not just because they're there," Rice professor Doug Natelson said in a statement. "If you can enhance the local field by a factor of 1,000, there are lots of things you can do in terms of sensors and non-linear optics. Anything that gives you a handle on what's happening at these tiny scales is very useful."

The light antenna is made with a nanogap with two gold tips that capture laser light. The optical antenna grabs the light and amplifies it into a tiny space, the researchers report.

Knowing how to concentrate light this way could lead to the development of optics and chemical and biological sensing on the single-molecule level.

When light is amplified, it makes the metal around it act like ripples in a pool. But when you create a magnetic field, it's hard to measure it because sometimes the metal's surface gives off a stronger field than the original light source.

But the researchers made the electrons flow at two different frequencies: one at a low frequency with a voltage and the other with a high frequency that was set off by light.

This difference was critical to measuring how much light was getting through the nanogap.

It's all about the level of control. This discovery could impact industry safety by sniffing out chemical leaks and improve defense and homeland security by sensing nuclear attacks or other environmental threats.

In related news, Harvard researchers made nano antennas that can focus light to improve the resolution of the microscope to image viruses and DNA. Traditional microscopes can only look at cells that are bigger than a wavelength of light. But the nano antenna gets around that problem and lets the scientists probe deeper into the microscopic world.

Image courtesy Natelson Lab/Rice University

This post was originally published on Smartplanet.com

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