Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


A road of no return

MIT team implements the first '1-way roads' for light that could lead to simpler lightwave technology

Light readily bounces off obstacles in its path. Some of these reflections are captured by our eyes, thus participating in the visual perception of the objects around us.

In contrast to this usual behavior of light, MIT researchers have implemented for the first time a one-way structure in which microwave light flows losslessly around obstacles or defects. This concept, when used in lightwave circuits, might one day reduce their internal connections to simple one-way conduits with much improved capacity and efficiency.

The laws of nature that govern the world around us allow for the propagation of light in both directions. If a light beam is observed propagating in a particular direction, one can also shine a light beam to propagate in the opposite (backward) direction. "The very fact that reflected beams are allowed to exist, combined with the fact that light at least partially reflects from most objects it encounters, makes optical reflections ubiquitous in nature," said MIT physics Professor Marin Soljaèiæ, the senior author of the study.

In a dramatic departure from this common phenomenon, a team made up of MIT physicists Dr. Zheng Wang, Dr. Yidong Chong, Prof. John Joannopoulos, and Prof. Marin Soljaèiæ have implemented and experimentally tested so-called topological photonic crystals that completely prohibit the existence of any lightwave back-reflections. The results, published in the 8th October 2009 edition of Nature, show the first experimental observation of the fascinating new phenomena and capabilities associated with microwave light propagating in this uniquely designed waveguide (a tunnel or "road" for guiding light).

Through the application of an external magnetic field, this specially designed waveguide induces unusual restrictions to the propagation of the light inside it. "We have now found a way to make light travel without bouncing back, by shining it through an array of small ceramic rods placed in a strong magnetic field," said Dr Zheng Wang, a lead author of the paper. For example, instead of light being able to travel to the right or to the left along this waveguide (as is traditionally expected), a magnetic field pointing upwards will allow light propagation only to the right, while a magnetic field pointing downwards allows for propagation of the light only to the left. "Once a particular forward direction of the light travel is chosen, no backward travel is permitted," said Dr. Yidong Chong, also a lead author of the paper. Therefore, light can never bounce back or reflect. Rather, it effortlessly routes around any obstacles and defects in its path without incurring any dissipation. "Loosely speaking the waveguide acts as a perfect cloak of the defect or obstacle in the path of the light" said Professor Joannopoulos, "the only difference is a phase shift of the guided light."

While the focus of the present work is in the microwave regime, in conventional optics, light reflections present a major roadblock to light-driven circuits reaching the same level of sophistication as widely used microelectronic circuits. A variety of practical applications, such as optical isolation and optical information storage, could potentially benefit from the novel and unparalleled one-way photonic behavior observed by the MIT team. Numerous applications that require strong interactions between light and matter could also gain from such an efficiency boost.

This work was funded by the Army Research Office (Institute for Soldier Nanotechnologies), and the National Science Foundation (MRSEC program).

Dr. Zheng Wang | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>