Text V Trapped Rainbow: New Technique To Slow Down, Stop And Capture Light Offers Bright Future For Internet, Powerful Computers

A. The negative index metamaterials that allow for unprecedented control over the flow of light have a sub-structure with tiny metallic components much smaller than the wavelength of the light and have recently been demonstrated experimentally for THz and infrared wavelengths. Covering the full rainbow colours in the visible frequency spectrum should be within science’s reach in the very near future.

B. The technique would allow the use of light rather than electrons to store memory in devices such as computers, enabling an increase in operating capacity of 1,000% by using light’s broad spectrum rather than single electrons. Slow light could also be used to increase the speed of optical networks, such as the Internet. At major interconnection points, where billions of optical data packets arrive simultaneously, it would be useful if we could control this traffic optically, by slowing some data packets to let others through. This system would work in the same way as traffic congestion calming schemes do on our motorways, when a reduction in the speed limit enables swifter overall flow of traffic.

C. Professor Ortwin Hess, his PhD student Kosmas Tsakmakidis of the Advanced Technology Institute and Department of Physics at the University of Surrey and Professor Alan Boardman from Salford University have revealed a technique which may be able to slow down, stop and capture light.

D. Professor Hess comments: Our “Trapped Rainbow” bridges the exciting fields of metamaterials with slow light research. It may open the way to the long-awaited realization of an “optical capacitor”. Clearly, the macroscopic control and storage of photons will conceivably find applications in optical data processing and storage, a multitude of hybrid, photonic devices to be used in optical fibre communication networks and integrated photonic signal processors as well as become a key component in the realisation of quantum optical memories. It may further herald a new realm of photonics with direct application of the ‘Trapped Rainbow’ storage of light in a huge variety of scientific and consumer fields.

E. Previous attempts to slow and capture light have involved extremely low or cryogenic temperatures, have been extremely costly, and have only worked with one specific frequency of light at a time. The technique proposed by Professor Hess and Mr Kosmas Tsakmakidis involves the use of negative refractive index metamaterials along with the exploitation of the Goos Hänchen effect, which shows that when light hits an object or an interface between two media it does not immediately bounce back but seems to travel very slightly along that object, or in the case of metamaterials, travels very slightly backwards along the object.

F. Professor Hess’ theory shows that if you create a tapered layer of glass surrounded by two suitable layers of negative refractive index metamaterials a packet of white light injected into this prism from the wide end will be completely stopped at some point in the prism. As different component ‘colours’ of white light have different frequencies each individual frequency would therefore be stopped at a different stage down the taper, thereby creating the ‘trapped rainbow’.

I Order the paragraphs. Explain your choice.

II Explain the terms and expressions in bold.

III Answer the questions.

• How can the system increase the speed of the Internet?

• Describe the technique proposed by Professor Hess. How can the rainbow be “trapped”?

• What prospects, according to Professor Hess, does slow light have?

Trapping a Rainbow: Researchers Slow Broadband Light Waves With Nanoplasmonic Structures

ScienceDaily (Mar. 15, 2011) — A team of electrical engineers and chemists at Lehigh University have experimentally verified the "rainbow" A. ______ effect, demonstrating that plasmonic structures can slow down light waves over a broad range of wavelengths.

The idea that a rainbow of broadband light could be slowed down or stopped using plasmonic structures has only recently been predicted in theoretical studies of B. ______. The Lehigh experiment employed focused ion beams to mill a series of increasingly deeper, nanosized C. ______ into a thin sheet of silver. By focusing light along this plasmonic structure, this series of grooves or nano-gratings slowed each wavelength of optical light, essentially capturing each individual color of the visible spectrum at different points along the grating. 1. ______.

While the notion of slowing light or trapping a rainbow sounds like ad speak, finding practical ways to control D. ____ -- the particles that makes up light -- could significantly improve the capacity of data storage systems and speed the processing of optical data.

The research required the ability to engineer a metallic surface to produce nanoscale periodic gratings with varying groove depths. This alters the optical properties of the nanopatterned metallic surface, called Surface Dispersion Engineering. The E. _____ surface light waves are then trapped along this plasmonic metallic surface with each wavelength trapped at a different groove depth, resulting in a trapped rainbow of light.

Through direct optical measurements, the team showed that light of different wavelengths in the 500-700nm region was "trapped" at different positions along the grating, consistent with computer simulations. To prepare the nanopattern gratings required "milling" 150nm wide rectangular grooves every 520nm along the surface of a 300-nm-thick silver sheet. 2._______.

"Metamaterials, which are man-made materials with feature sizes smaller than the wavelength of light, offer novel applications in nanophotonics, photovoltaic devices, and biosensors on a chip," said Filbert J. Bartoli, principal investigator, professor and chair of the Department of Electrical and Computer Engineering. "Creating such nanoscale patterns on a metal film allows us to control and manipulate F. _____ . The findings of this paper present an unambiguous experimental demonstration of rainbow trapping in plasmonic nanostructures, and represents an important step in this direction."

"This technology for slowing light at room temperature can be integrated with other materials and components, which could lead to novel platforms for optical G. ____. 3. ______, said Qiaoqiang Gan, who completed this work while a doctoral candidate at Lehigh University, and is now an assistant professor in the Department of Electrical Engineering , State University of New York at Buffalo.

The study was funded by the National Science Foundation. 4. ______.

I. Fill in the terms: metamaterials, photons, circuits, grooves, trapping, light propagation, broadband (A - G).

II. Fill in the missing phrase:

a. It is published in the current issue of the Proceedings of the National Academy of Sciences.

b. The findings hold promise for improved data storage, optical data processing, solar cells, bio sensors and other technologies.

c. The ability of surface plasmons to concentrate light within nanoscale dimensions makes them very promising for the development of biosensors on chip and the study of nonlinear optical interactions

5. While intrinsic metal loss on the surface of the metal did not permit the complete "stopping" of these plasmons, future research may look into compensating this loss in an effort to stop light altogether.

III. Answer the questions:

• Describe the way to slow down light.

• What are metamaterials?

• Summarize the possible uses of slow light. Use any extra information you can.

1. IV. Speaking. Introducing the innovation in your company.

2. Role-play an IT company meeting in which you, being a member of the Research and Development Department, are going to point out the benefits of the “trapping light” technology for the company. Try to convince the managers to pay special attention to this innovation.