BRIDGE TO SOMEWHERE: A nanomechanical resonator, or bridge [inset], vibrates when laser light is routed through it [above]. Such light-powered motion could be used to drive minuscule on-chip devices without resorting to electricity.
Image: H. Tang, Yale University
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Solar power is great for converting light energy into electricity. But what about harnessing light energy directly? After all, photons—discrete packets of light energy—exert force themselves, albeit on a pretty small scale.
In a new study, a team of researchers from Yale University and the University of Washington reports doing just that, also on a pretty small scale—vibrating a tiny mechanical object physically by shining light through it.
Light-powered mechanics could form the basis for nanoscale components such as switches and routers, all operating off the grid, so to speak. "We can use light force to replace electrostatic force," says Hong Tang, an assistant professor at Yale's School of Engineering & Applied Science and co-author of the study published today in Nature. "You don't need to apply voltage, you just need to pass light through it."
The group's experimental setup confines laser light in an on-chip silicon waveguide. The waveguide routes the light through a narrow section, 10 microns in length and just 110 nanometers thick, that resonates ever so slightly as the light passes through. (A micron is a millionth of a meter; a nanometer is a billionth of a meter.) "It's a little bridge, a nanomechanical resonator," Tang says. "It's the simplest resonator you can find."
Other approaches that have harnessed the force of light have primarily exploited the so-called radiation pressure force, a sort of direct hit that occurs when photons strike an object. But Tang's team was able to move its resonator in a direction transverse, or crosswise, to the light's path, using an effect called optical gradient forces. In other words, the horizontal flow of light through the resonator induces it to vibrate up and down.
Those vibrations are so tiny that Tang and his colleagues used a second laser to detect the motion. "When we talk about nanomachines, we cannot think of this nanomachine like it's your hand moving around or some tools moving around—that's the wrong picture," Tang says. "Because they are small, the motion has to be small, too."
Tang calls this demonstration a proof of principle, adding that his group will seek to increase the frequency of the vibrations by more than 100 times. In this study, the bridge's resonant frequency was in the neighborhood of 10 megahertz, or millions of cycles per second. Tang would like to be able to get a similar device vibrating at much higher speeds, above the gigahertz range—in the billions of cycles per second.
Some observers see a bright future for such light-induced motion. "With this work, optical trapping 'grows up,'" says Naomi Halas, a professor of electrical and computer engineering and of chemistry at Rice University. "Optical trapping has been so important in enabling new research approaches in atomic physics and biophysics, but with this work it gets implemented on a silicon chip, where it is clear ... that it will prove to be a valuable approach in many technological applications."
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13 Comments
Add CommentHoly pants. That's incredible. The future will be indistinguishable from magic. If we can hang on to life on earth long enough...
Reply | Report Abuse | Link to thisVery cool.
I'm disappointed with this reporting. How many Newtons are generated by the resonance? What is the displacement? This article is missing mechanical information that would have made it useful. This is just another piece of hammed up reporting with no other purpose than to sensationalize an otherwise feeble piece of news.
Reply | Report Abuse | Link to thissapbucket you do realise that this is Scientific American not Nature right? This is science and technology headline news not a peer reviewed journal. Im sure Scientific American wont mind if you dig into this subject on your own if youre interested. Or is it Scientific Americans responsibility to give you what you want when you want it? I really doubt it though because I dont think they can do that for both of us at the same time. Hopefully there will be an article posted soon on new treatments for chronic cynicism and a nasty temperament. Keep posted.
Reply | Report Abuse | Link to thisI'm disappointed with sapbucket's reaction to this item. His (it must be a "he" ;-) response is lacking in imagination. And knowledge.
Reply | Report Abuse | Link to thisImagination, in that he fails to appreciate the developments demonstrations of principle like this could lead to in the middle term (not even the long term). He fails to think out of the box by not linking the hundreds of small discoveries at this level that can be exploited together to create something bigger than its component parts. You need imagination to extrapolate the features of any particular discovery to potential future uses.
Knowledge, in that he seems to be unaware of the advances already made in the real current commercialization of nanotechnology in the fields of materials, mechanical engineering, energy, electricity, computing, research equipment, etc. And the ways these are being linked up to amplify their individual impact.
We already have the extreme miniaturization used now in most aspects of computing, with the prospect (in the short term) of new materials improving substrata, transistors, power usage, current transmission between various parts of chips, smaller and more precise laser (optical) technology for huge increases in media capacity, etc. In the mid term we have the prospect of 3D storage technologies, wireless information transmission of unprecedented amounts of information over unprecedented areas and distances, etc.
All this will be realized in an explosion in the storage, availability, visualization, conceptualization, and exchange of knowledge and its application in real social production.
If we follow sapbucket's blinkered approach, life on earth is in danger. If we share hotblack's enthusiasm, there might still be hope.
Some poeple are born to bicth and never get the big picture. Others gets bribes here and there and creates a web of general knowledge that enable to be amazed of what the big picture provide in the understanding of our world and begin to see further and include understanding of parallels universes. Although, extremes on one end and the other are useful to waken the sleepy middle into thinking a little bit it is not n飥ssary to pay more attention because looking with no end for the thick on the camel's back too much knit picking. Have a nice day "Sapbucket"
Reply | Report Abuse | Link to thiswhats hotblack
Reply | Report Abuse | Link to thisI can think of a few uses right from the get go.
Reply | Report Abuse | Link to thisFirst of all using a frequency divider, a mechanical version of the electronic one, youcould use the slower motion to move nano-scopic robots. This could be the main source of locomtion without the need forenergy wasting conversions into electrical then to magnetic and back to mechanical.
The nano bots that move with light have many possible applications from self healing space ship "skin" to protection of fruits and vegitables from biological enemies.
That's cool!
Reply | Report Abuse | Link to thisSapbucket does have a good poing in that - if you have an article with a headline that inlcudes the words "Power & Light" - make that information available. These details are the language and subject of the article - and facilitate & support the suggestions listed in all the subsequent comments and therefore is of greater value to readers. It seems that Sapbucket already leaped over imagination and knowledge and was already into the mechanics of application with this point.
Reply | Report Abuse | Link to thisxiyveqccc.
Reply | Report Abuse | Link to thisThat is correct Andthen....
Reply | Report Abuse | Link to thisandthen is correct... plus after imagination one is going to think of the mechanical importance so then he can imagine again..
Reply | Report Abuse | Link to thisIt's going to be a brave "little" world soon...
Reply | Report Abuse | Link to this