Physics

Nanoscale device emits light as bright as an object 10,000 times its size

A diagram of the microscopic nanoresonator
A diagram of the microscopic nanoresonator
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A diagram of the microscopic nanoresonator
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A diagram of the microscopic nanoresonator

Amplifying light a few hundred times with magnifying lenses is easy.Amplifying light by altering the resonant properties of light itself is a muchmore difficult proposition. However, if recent research by engineers at theUniversity of Wisconsin-Madison (UWM) engineers is anything to go by, the effort iswell worth it: They claim to have constructed a nanoscale device that can emitlight as powerfully as an object more than 10,000 times its size.

According to the researchers, the light-amplifying properties of the device – known as a nanoresonator – are analogous to that of a guitar string that vibrates in sympathy to local acoustic energy. As such, this tiny optical device receives light energy from its surroundings to produce a light output much larger than expected. This, according to the team, offers many advantages in imaging techniques over normal lenses, as the device's light-harvesting ability is not limited by its physical properties to direction and size.

"Making an object look much 10,000 times larger than its physical size has lots of implications in technologies related to light," says assistant professor Zongfu Yu. "We are developing photodetectors based on this technology, and, for example, it could be helpful for photographers wanting to shoot better quality pictures in weak light conditions."

Just as sound can be made to resonate and amplify when a standing wave is generated in a low-loss reflection chamber, so too can light be amplified by an environment that manipulates the physical properties of light-wave energy. The UWM researchers exploited this fact in their research to engineer an artificial material in which the wavelength of light is much longer than in a vacuum, thereby allowing the light to resonate much more strongly.

The material also condenses light to a size smaller than its wavelength, which means that a large amount of light energy is captured before being reflected onto a much larger surface where it is widely scattered, providing a much-magnified version of the original light energy. In this way, even microscopically-small objects can be made to appear enormous in the amplified light image.

"The device makes an object super-visible by enlarging its optical appearance with this super-strong scattering effect," says PhD student of electrical and computer engineering at UWM, Ming Zhou.

With the nanoresonator’s ability to absorbcopious amounts of energy from light, the team also believes that their devicepresents possibilities in high-efficiency solar cells. Yu believesthat the ability to re-emit unwanted energy in the infrared during solarcapture would allow the device to be self-cooling, further increasing itsefficiency.

"This research opens up a new way tomanipulate the flow of light, and could enable new technologies in lightsensing and solar energy conversion," says Yu.

The results of the research were recently published in thejournal PhysicalReview Letters.

Source: Universityof Wisconsin-Madison

5 comments
martinkopplow
So there obviously is still no free lunch, but all food you find can be made to taste like your favorite dish? That's a nice idea. It could make several applications that work best on a narrow spectrum much more efficient. I see quite some potential. Keep up the good work!
jerryd
Sorry this doesn't make sense. You can only get the energy you put in, out. Amplifying means you just change the size, not the amount except for losses so you get less out, not more. Now switching wavelengths could help PV to ones it can absorb but again you always get less energy out than you put in. To really amplify you need to add energy, then make it in what you want.
mach37
There seems to be a problem with translation to English; the number of photons emitted seem to be the determining factor in how bright an object is, rather than the size of the object. Isn't the nanoresonator emitting more photons than are being fed into it? Also, changing wavelength changes color, which seems to not be considered in this discussion; "condenses light to a size smaller than its wavelength" just doesn't make sense.
Indiver716
Perhaps this technology could be used to enhance the light sensitivity of telescopes as well without the cost and precision grinding needed for large mirrors.
EnochAroko
I was contemplating the difficulty of observing light emitting objects like stars caused by their brightness and distance when I came across this nanoresonator research. My thoughts are that if light can be diffused to a comfortable level and then amplified, we may be able to see distant objects much better than using telescopes. This research could ursher in new powerful astronomical devices that can expand our knowledge of the universe. I hope to heat more from Ming Zhou and UWM
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