Light-bending tech shrinks kilometers-long radiation system to millimeter scale

October 26, 2018 by Kayla Wiles, Purdue University
A new device bends visible light inside a crystal to produce "synchrotron" radiation (blue and green) via an accelerating light pulse (red) on a scale a thousand times smaller than massive facilities around the world. Credit: University of Michigan image/Meredith Henstridge

The DESY accelerator facility in Hamburg, Germany, goes on for miles to host a particle making kilometer-long laps at almost the speed of light. Now researchers have shrunk such a facility to the size of a computer chip.

A University of Michigan team in collaboration with Purdue University created a new device that still accommodates speed along circular paths, but for producing lower light frequencies in the of applications such as identifying counterfeit dollar bills or distinguishing between cancerous and healthy tissue.

"In order to get light to curve, you have to sculpt every piece of the light beam to a particular intensity and phase, and now we can do this in an extremely surgical way," said Roberto Merlin, the University of Michigan's Peter A. Franken Collegiate Professor of Physics.

The work is published in the journal Science. Ultimately, this device could be conveniently adapted for a computer chip.

"The more terahertz sources we have, the better. This new source is also exceptionally more efficient, let alone that it's a massive system created at the millimeter scale," said Vlad Shalaev, Purdue's Bob and Anne Burnett Distinguished Professor of Electrical and Computer Engineering.

The device that Michigan and Purdue researchers built generates so-called "synchrotron" radiation, which is electromagnetic energy given off by charged particles, such as electrons and ions, that are moving close to the speed of light when magnetic fields bend their paths.

Several facilities around the world, like DESY, generate synchrotron radiation to study a broad range of problems from biology to materials science.

This accelerating light pulse (left) met expectations (right) that it would follow a curved trajectory and emit radiation at the terahertz frequencies of security technology and other sensing applications. Credit: University of Michigan video/Meredith Henstridge

But past efforts to bend light to follow a circular path have come in the form of lenses or spatial light modulators too bulky for on-chip technology.

A team led by Merlin and Meredith Henstridge, now a postdoctoral researcher at the Max Planck Institute for the Structure and Dynamics of Matter, substituted these bulkier forms with about 10 million tiny antennae printed on a lithium tantalite crystal, called a "metasurface," designed by the Michigan team of Anthony Grbic and built by Purdue researchers.

The researchers used a laser to produce a pulse of visible light that lasts for one trillionth of a second. The array of antennae causes the light pulse to accelerate along a curved trajectory inside the crystal.

Instead of a charged particle spiraling for kilometers on end, the pulse displaced electrons from their equilibrium positions to create "dipole moments." These dipole moments accelerated along the curved trajectory of the , resulting in the emission of synchrotron radiation much more efficiently at the terahertz range.

"This isn't being built for a computer chip yet, but this work demonstrates that could eventually help develop on-chip terahertz sources," Shalaev said.

Explore further: Researchers develop small device that bends light to generate new radiation

More information: "Synchrotron radiation from an accelerating light pulse" Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aat5915

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14 comments

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Robin_Whittle
4.4 / 5 (7) Oct 26, 2018
The paper is behind a paywall. A PhD thesis and article provide more information:

https://deepblue....st_1.pdf

https://www.osapu...-678.pdf

I read the article and could not understand what "accelerating light" meant in this context, but the above animated GIF helps: a bright spot of light moves through a crystal in a small curve, so the spot is accelerating, in this case, in the vertical direction as it travels in the horizontal direction. If the spot causes an electrical field, then this creates an accelerating electrical field which, due to the small dimensions and times involved, will create a broadband terahertz pulse. Exactly how they use the metasurface to sculpt a short laser pulse into this interfering wavefront I don't know. I would probably need to read the above paper another time and chase a bunch of references, or read the thesis.
Phyllis Harmonic
4 / 5 (4) Oct 26, 2018
Thanks, Robin. Fascinating techniques being employed here!
Robin_Whittle
4.4 / 5 (7) Oct 26, 2018
There's nothing "so-called" about synchrotron radiation. Phys.org writers use "so-called" to vast excess. Google reports in excess of 20k instances. It might occasionally be apt for a term which is common and awkward or somehow less appropriate than some other term.

Most of the uses of this "so-called" in phys.org seem intended by the writer to pander to what the writer perceives as a the limited vocabulary of readers, who they think might be scared off by overly technical terms. The same goes for the bland titles of many phys.org articles, stripped of interesting specific, apt, terminology. Perhaps a few readers prefer this dumbed-down writing style, but I would be surprised if the majority do.

This page:

https://phys.org/...ace.html

shows an alternative and much bulkier approach to creating a spot of light which moves very rapidly across a surface
Captain Stumpy
4.5 / 5 (8) Oct 26, 2018
seem intended by the writer to pander to what the writer perceives as a the limited vocabulary of readers, who they think might be scared off by overly technical terms
@Robin_Whittle
it's entirely possible that they made the decision to "dumb it down" based upon the more prolific pseudoscience posters in the comments section, which would explain a lot.
TheGhostofOtto1923
1.8 / 5 (5) Oct 27, 2018
Most of the uses of this "so-called" in phys.org seem intended by the writer to pander to what the writer perceives as a the limited vocabulary of readers, who they think might be scared off by overly technical terms. The same goes for the bland titles of many phys.org articles, stripped of interesting specific blah
I guess youre so eager to criticize that you fail to realize that physorg mostly reprints PR news releases verbatim from a myriad of academic and govt sites and so is not responsible for their literary quality or content.

Dumbass.
szore88
2 / 5 (4) Oct 28, 2018
Pseudoscience... Like GW?
FredJose
1.9 / 5 (9) Oct 29, 2018
upon the more prolific pseudoscience posters in the comments section,

@Stumpy - you do realize that the BB theory, Abiogenesis and Darwinian evolution falls squarely into the pseudoscience category, right?
There's no observational evidence to support the idea that stars can form by themselves in the vacuum of space from clouds of gas. That just goes against the most basic laws of physics that we know. Ask if ANYONE has every witnessed said clouds to overcome the Jeans Mass Limit.
Or planets forming from clouds of dust? Similar problems.
Or life spontaneously arising from dead materials - has anyone observed this magical myth?
Or ANY observational evidence for one kind (family if you wish) of organisms jumping the breach and morphing into another kind all by themselves?

If you have zero supporting observational evidence and no way to verify or falsify the claims, how can that be science?

One is left with but one conclusion - those items are all PSEUDO-SCIENCE!
granville583762
2.6 / 5 (5) Oct 29, 2018
Dipoles
phys.org> The researchers used a laser to produce a pulse of visible light that lasts for one trillionth of a second. The array of antennae causes the light pulse to accelerate along a curved trajectory inside the crystal these dipole moments accelerated along the curved trajectory of the light pulse, resulting in the emission of synchrotron radiation much more efficiently at the terahertz range

The light pulse displaced electrons creating dipole moments, these dipole moments accelerated along the curved trajectory of the light pulse, emitting synchrotron radiation

Really, dipole moments travelled the curved trajectory of the light pulse
When did light travel in circles
And when did dipoles travel on the path of light

Really, dipole moments travelled the curved trajectory of the light pulse emitting synchrotron radiation
Synchrotron radiation is charged particles in acceleration around dipole moments magnetic field
granville583762
3 / 5 (6) Oct 29, 2018
Synchrotron radiation in the photo-electric effect.

Synchrotron radiation is charged particles in acceleration around dipole moments magnetic field
Light displaces electrons
Electrons are charged particles and dipole moments.
Electrons as charged particles travel dipole moments magnetic field in synchrotron radiation.
It goes without say an electron cannot reasonably travel its own or another electrons dipole moments magnetic field .
There is relative size to the magnet fields dipole moment, otherwise, is it possible for an electron, as a charged particle, to spiral around its own dipole moments magnetic field, in synchrotron radiation.

This would be interesting, if this were possible!
granville583762
2.7 / 5 (7) Oct 29, 2018
Pseudoscience
upon the more prolific pseudoscience posters in the comments section

FredJose> BB theory, Abiogenesis and Darwinian evolution falls squarely into the pseudoscience category,
There's no observational evidence to support the idea that stars can form by themselves in the vacuum of space from clouds of gas.
Ask if ANYONE has every witnessed said clouds to overcome the Jeans Mass Limit.
Or planets forming from clouds of dust? Similar problems.
Or life spontaneously arising from dead materials - has anyone observed this magical myth?
One is left with but one conclusion - those items are all PSEUDO-SCIENCE!

FredJose, You are correct; Pseudoscience is unobserved and unproven science which is by definition is unobserved.
Pseudoscience!
TheGhostofOtto1923
3.7 / 5 (6) Oct 29, 2018
@Stumpy - you do realize that the BB theory, Abiogenesis and Darwinian evolution falls squarely into the pseudoscience category, right?
There's no observational evidence
??? A godder talking about evidence? If you believed in evidence for just one minute fred, you would have to accept the conclusive evidence that the god of abraham doesnt exist.

That's the thing about evidence - you cant pick and choose whatever you like and discard the rest.

You've got to accept it all.
antialias_physorg
5 / 5 (3) Oct 29, 2018
Phys.org writers use "so-called" to vast excess.

No they do not. The above article is not authored by phys.org (pretty much zero percent articles on phys.org are authored by them. Phys.org is an aggregation site - not a content creation site.)
The article is taken verbatim from the Purdue university PR site (just google the first sentence and you will usually find the original source).
Captain Stumpy
4.3 / 5 (6) Oct 29, 2018
for clarification purposes
(just google the first sentence and you will usually find the original source).
actually, it is usually either tagged in the author byline or noted in the "more information" section

(I don't know if that shows up on phone apps though)

in this case, it's both
October 26, 2018 by Kayla Wiles, Purdue University
Journal reference: Science

Provided by: Purdue University
the article, as Antialias stated, comes from Purdue and the Study is published in Science Magazine

.

I won't even bother elucidating the abject stupidity posted by fred in his religious fanatical state as it's based solely upon his ignorance of science (which is then exacerbated by yet another trolling idiot)
TheGhostofOtto1923
1 / 5 (3) Oct 30, 2018
No they do not. The above article is not authored by phys.org (pretty much zero percent articles on phys.org are authored by them. Phys.org is an aggregation site - not a content creation site.)
The article is taken verbatim from the Purdue university PR site (just google the first sentence and you will usually find the original source)
Isnt that kyuute? Aa posts what I said like I'm on his ignore list when we both know he reads every word I write.

What a loser.

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