Navigation Links
Taming mavericks: Stanford researchers use synthetic magnetism to control light

Magnetically speaking, photons are the mavericks of the engineering world. Lacking electrical charge, they are free to run even in the most intense magnetic fields. But all that may soon change. In a paper published in Nature Photonics, an interdisciplinary team from Stanford University reports that it has created a device that tames the flow of photons with synthetic magnetism.

The process breaks a key law of physics known as the time-reversal symmetry of light and could yield an entirely new class of devices that use light instead of electricity for applications ranging from accelerators and microscopes to speedier on-chip communications.

"This is a fundamentally new way to manipulate light flow. It presents a richness of photon control not seen before," said Shanhui Fan, a professor of electrical engineering at Stanford and senior author of the study.


The ability to use magnetic fields to redirect electrons is a founding principle of electronics, but a corollary for photons had not previously existed. When an electron approaches a magnetic field, it meets resistance and opts to follow the path of least effort, travelling in circular motion around the field. Similarly, this new device sends photons in a circular motion around the synthetic magnetic field.

The Stanford solution capitalizes on recent research into photonic crystals materials that can confine and release photons. To fashion their device, the team members created a grid of tiny cavities etched in silicon, forming the photonic crystal. By precisely applying electric current to the grid they can control or "harmonically tune," as the researchers say the photonic crystal to synthesize magnetism and exert virtual force upon photons. The researchers refer to the synthetic magnetism as an effective magnetic field.

The researchers reported that they were able to alter the radius of a photon's trajectory by varying the electrical current applied to the photonic crystal and by manipulating the speed of the photons as they enter the system. This dual mechanism provides a great degree of precision control over the photons' path, allowing the researchers to steer the light wherever they like.


In fashioning their device, the team has broken what is known in physics as the time-reversal symmetry of light. Breaking time-reversal symmetry in essence introduces a charge on the photons that reacts to the effective magnetic field the way an electron would to a real magnetic field.

For engineers, it also means that a photon travelling forward will have different properties than when it is traveling backward, the researchers said, and this yields promising technical possibilities. "The breaking of time-reversal symmetry is crucial as it opens up novel ways to control light. We can, for instance, completely prevent light from traveling backward to eliminate reflection," said Fan.

The new device, therefore, solves at least one major drawback of current photonic systems that use fiber optic cables. Photons tend to reverse course in such systems, causing a form of reflective noise known as backscatter.

"Despite their smooth appearance, glass fibers are, photonically speaking, quite rough. This causes a certain amount of backscatter, which degrades performance," said Kejie Fang, a doctoral candidate in the Department of Physics at Stanford and the first author of the study.

In essence, once a photon enters the new device it cannot go back. This quality, the researchers believe, will be key to future applications of the technology as it eliminates disorders such as signal loss common to fiber optics and other light-control mechanisms.

"Our system is a clear direction toward demonstrating on-chip applications of a new type of light-based communication device that solves a number of existing challenges," said Zongfu Yu, a post-doctoral researcher in Shanhui Fan's lab and co-author of the paper. "We're excited to see where it leads."


Contact: Andrew Myers
Stanford School of Engineering

Related biology technology :

1. Taming light with graphene
2. Stanford engineers use nanophotonics to reshape on-chip computer data transmission
3. Stanford engineers weld nanowires with light
4. Unzipped carbon nanotubes could help energize fuel cells and batteries, Stanford scientists say
5. Stanford engineers perfecting carbon nanotubes for highly energy-efficient computing
6. Stanford scientists spark new interest in the century-old Edison battery
7. Stanford faculty awarded $2.2 million for innovative energy research
8. New England Biolabs Introduces Polbase, an Information Repository of Scientific Data for Polymerase Researchers
9. In new quantum-dot LED design, researchers turn troublesome molecules to their advantage
10. Multidisciplinary team of researchers develop world’s lightest material
11. Researchers shrink tumors and minimize side effects using tumor-homing peptide to deliver treatment
Post Your Comments:
(Date:12/1/2015)... 1, 2015 Frost & Sullivan is ... program addresses ways companies can innovate and transform ... --> ... --> ... well as the disrupting factors altering the industry, ...
(Date:12/1/2015)... (PRWEB) , ... December 01, 2015 , ... ... (AFM) announces Park NX10 SICM Module, an add-on scanning ion conductance microscopy module ... power of SICM to an AFM. , Park SICM benefits virtually all materials ...
(Date:12/1/2015)... , December 1, 2015 Dr. Harry Lander , President ... serving as Chief Science Officer and recruits five ... Harry Lander , President of Regen, expands his role to ... recruits five distinguished scientists to join advisory team ... expands his role to include serving as ...
(Date:11/30/2015)... ... November 30, 2015 , ... Global Stem Cells Group ... a new closed system for isolating adipose-derived stem cells. The announcement starts a new ... adipose tissue. SVF is a component of the lipoaspirate obtained from liposuction of excess ...
Breaking Biology Technology:
(Date:11/20/2015)... , November 20, 2015 NXTD ... focused on the growing mobile commerce market and creator ... Gino Pereira , was recently interviewed on The ... air on this weekend on Bloomberg Europe , ... . --> NXTD ) ("NXT-ID" or the ...
(Date:11/17/2015)... PARIS , November 17, 2015 ... November 2015.   --> Paris from ... --> DERMALOG, the biometrics innovation leader, has invented the ... and fingerprints on the same scanning surface. Until now two ... fingerprints. Now one scanner can capture both on the same ...
(Date:11/12/2015)... golden retriever that stayed healthy despite having the gene ... new lead for treating this muscle-wasting disorder, report scientists ... and Harvard and the University of São Paolo in ... pinpoints a protective gene that boosts muscle regeneration, ... Children,s lab of Lou Kunkel , PhD, is ...
Breaking Biology News(10 mins):