A new light wave

Aug 12, 2013 by Angela Herring
Yongmin Liu, an assistant professor with joint appointments in the Department of Mechanical and Industrial Engineering and the Department of Electrical and Computer Engineering, researches nano-optics and metamaterials. Credit: Brooks Canaday

Hold a magnifying glass over the driveway on a sunny day and it will focus sunlight into a single beam. Hold a prism in front of the window and the light will spread out into a perfect rainbow. Lenses like these have been used for thousands of years, including, most recently, for sophisticated optical devices.

Until now, all lenses have shared one big limitation: It's impossible to focus light into a beam that's smaller than half of the light's wavelength, said assistant professor Yongmin Liu. It would be like trying to compress into a cylinder whose diameter was smaller than the balls themselves.

This so-called "" has thus far prevented technologies based on (instead of electrons) from competing with the small sizes achieved in —like the tiny chips powering our palm-sized cell phones.

But an emerging field called plasmonics has turned this age-old truth on its head and could revolutionize high-tech devices from super-resolution , to ultra-bright LED displays, to high-speed computers, said Liu. Researchers are now able to focus light into a beam as small as 10 in diameter, a small fraction of the shortest wavelength in the .

The trick is to get the photons and electrons to behave as one. When you do this, the resulting particle emerges with the features and advantages of each. The unique combination could lead to the creation of an "ultra-small, ultra-fast, and energy efficient device," said Liu, who holds joint appointments in the Department of Mechanical and Industrial Engineering and the Department of Electrical and Computer Engineering.

Yet, despite this exciting advancement, Liu wasn't satisfied. The current devices in this field are all based on . In a liquid environment, Liu conjectured, he would have more control on the devices' properties. Perhaps he could develop devices that are not only small and fast, but also reconfigurable and multifunctional.

Liu teamed up with Tony Jun Huang, an engineering professor at Pennsylvania State University who studies optofluidics, Penn State postdoctoral fellow Chenglong Zhao and graduate student Yanhui Zhao, and Nicholas Fang, an associate professor of mechanical engineering at M.I.T. Combining their expertise, the team created the world's first "plasmofluidic lens," which uses water bubbles to manipulate light instead of glass or polymers. This work was published Friday in the journal Nature Communications.

Just as with glass blowing, the bubbles are created from heat—only instead of coming from a burning metal rod six feet long, this heat comes from a tiny laser beam just a few micrometers wide. And just like soap bubbles in a bathtub, the microscopic water bubbles are free to move around a surface, such as a piece of gold film.

The researchers can use the laser beam to change the size, shape, and location of the bubbles, allowing them to control exactly how and where the light is directed. With one lens, they can simultaneously focus, scatter, and align the photons from a single beam of light.

Combining the size capabilities of electronics with the speed capabilities of optics, and the versatility of the fluid environment, said Liu, the approach provides fertile ground for a host of new technologies we haven't yet imagined. In particular, it could open up an entirely new class of biomedical diagnostic tools.

Explore further: New insights found in black hole collisions

More information: www.nature.com/ncomms/2013/130… full/ncomms3305.html

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User comments : 4

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1 / 5 (8) Aug 12, 2013
this sounds ilke an AMAZING collaboration. i'm sure people will poopoo the idea of using water, but the brain in its highly watery state is capable of pruning its own circuitry on time scales that can modulate feedback from the actualy operations of the circuitry.

long term memories are physical changes of brain circuitry responding to the actual millisecond scale firing of circuit networks. water circuits could conceivably be altered on as as needed basis. this may be merely experimental, and ultimately limited in key performance metrics for practical usage, but there is probably a lot of learning that can be milked from this kind of experimental setup.
1 / 5 (3) Aug 12, 2013
This could bring some amazing toys for astrophysical applications, particularly in miniaturizing collecting surfaces on space based observatories.
1 / 5 (9) Aug 13, 2013
Use Water as Reflecting Mode- I see light beyond sun.Think over - light aligned flow-field modes. Use Mirror Glass for four-mode Flow of light.Dearch further Techniques- One can come with Field mode profile from Earth Plane.
Plasma Regulated Electromagnetic phenomena in magnetic Field Environment can unravel many coplexities that puzzles astronomers.
5 / 5 (1) Aug 13, 2013
This could bring some amazing toys for astrophysical applications

Not only for astrophysics. This essentialy opens up the idea of totally flat optical lenses (credit card thin cameras with autofocus anyone?). Could also be used in ultracompact beamers.

But I like this part of the article best:
Perhaps he could develop devices that are not only small and fast, but also reconfigurable and multifunctional

It seems to me that this approach can not only be use for optical properties but also electrical/magnetic or even mechanical ones. While not as fast as transistors the possibility to have a fully, functionally reconfigurable surface seems mind boggling. (Think switching between hydrophilic and hydrophobic states, using surfaces as processors or memory as needed, changing resistance/slip properties on the fly, ... )

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