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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.

IV. Speaking. Introducing the innovation in your company.

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.

Unit VI. Laser Could Rival Sun's Energy (From Live Science)

Ed Moses, the director of a high-energy physics adventure to produce the world's most powerful laser, talks of the "grand challenge'' that has consumed him for the past five years, namely to create in a laboratory the energy found at the center of the sun.

In a building the size of a football stadium, engineers have assembled the framework for a network of 192 laser beams, each traveling 1,000 feet to converge simultaneously on a target the size of a pencil eraser. The trip will take one-thousandth of a second during which the light's energy is amplified many billions of times to create a brief laser pulse 1,000 times the electric generating power of the United States. The goal is to create unimaginable heat -- 180 million degrees Farenheit -- and intense pressure from all directions on a BB-size hydrogen fuel pellet, compressing it to one-thirtieth of its size. The result, the scientists hope, will be a fusing of atoms so that more energy is released than is generated by the laser beams, something scientists call fusion ignition. It is what happens when a hydrogen bomb explodes.

Four of the beams have been tested. When completed in 2008, the National Ignition Facility, or NIF, as the laser at the Lawrence Livermore National Laboratories is called, will dwarf many times over any laser to date. It will provide a platform for many experiments in high-energy and high-density physics, from learning more about the planets and stars to advancing the elusive hunt for fusion energy to generate electric power, Moses says. "You have to think of this like the Hubble,'' he says, referring to the space telescope. "It's a place where you will see things and do things that you couldn't do anywhere else.''

If NIF achieves fusion ignition, it will for the first time in a laboratory simulate the pressures and heat of a nuclear explosion, allowing nuclear weapons scientists to study the performance and readiness of the country's aging nuclear arsenal without actually detonating a nuclear device. The NIF laser "is essential to assessing the potential performance of nuclear weapons,'' says Energy Secretary Samuel Bodman. He says the experiments will help determine the effects of aging on warheads and help assure they will work as expected, should they be needed.

There have been other lasers, including a 10-beam Livermore project called Nova. NIF will produce 40 times to 60 times more energy. "It's the difference between a car and a jet engine,'' Moses says. For many supporters the "pass-fail'' is whether the NIF lasers will achieve fusion ignition.

"We never intended to spend $5 billion to $6 billion to build a laser facility for ... civilian research,'' says Sen. Pete Domenici, R-N.M., chairman of the Senate subcommittee that funds the NIF program.

Among some people, fusion ignition "has become the poster child for NIF being successful'' and that shouldn't be the case, counters George Miller, a former nuclear weapons designer and bomb tester who heads the project. He says there are many other experiments for which NIF will be valuable to nuclear weapons scientists.

The new team tackled a variety of problems. By 2003, the dust issue was solved by building a massive clean room and installing the optics in modular dust-free units. Engineers found new ways to produce the thousands of highly polished pieces of laser glass. A faster way was found to grow high-quality crystals that convert the beams to ultraviolet just before they strike the target.

And with four of the planned 192 beams operating, new tests suggested strongly that when the system was fully operating, enough energy would be produced to -- theoretically, at least -- achieve ignition.

Last year, however, a new complication emerged -- not over the laser but the pea-size pellet that contains the hydrogen fuel that will be ignited by the lasers to achieve fusion ignition. Could the pellet be manufactured to the required specifications? Once its shell was to be made of plastic, but that idea was abandoned. Now the choice is beryllium, a metallic element that can withstand intense heat, is molecularly stable and is a good conductor. It still is uncertain whether beryllium can be machined to specification, according to technicians who have monitored the program. Last year Congress directed another outside review to report how the development of a beryllium target might affect NIF's timetable.

Like previous challenges in the project's history, the beryllium issue will be resolved, Miller and Moses believe. While the massive laser may one day have a broad range of scientific uses -- some not even envisioned by today's scientists -- the immediate focus remains assuring the reliability of the nation's nuclear arsenal without actually testing the weapons (Retrieved from: http://www.livescience.com/282-laser-rival-sun-energy.html).

I. Find the words in the article that might correspond to these definitions:

6. ________ the quality, condition, or fact of being exact and accurate.

7. ________ an essential supporting structure of a building, vehicle, or object.

8. _________ make (something) more marked or intense.

9. _________ a small, rounded, compressed mass of a substance.

10. _________ the action of setting something on fire or starting to burn.

11. __________ a standard for the hardware of a computer system, which determines what kinds of software it can run.

12. _________ the explosive head of a missile, torpedo, or similar weapon.

13. _________ a department of an institution with a specific function.

14. _________ a circumstance that complicates something; a difficulty.

15. _________ remain undamaged or unaffected by; resist.

II. Decide whether the statements are true or false.

- The laser that could rival the Sun has recently been created.

- To achieve fusion ignition it is necessary to create heat and pressure on a fuel pellet.

- The NIF is believed to be a unique project because of its space telescope.

- The NIF laser is going to be used for testing weapons.

- Civilian research is the Senate's top priority.

- New crystals have been grown to eliminate the problem of dust.

- Due to the NIF achieving ignition is no longer mere theory nowadays.

- A new pellet has already been designed to meet the specifications.

III.Summarize the following points:

- The kind of construction that harbours the NIF laser;

- The possible uses of the NIF laser;

- The principle of its work;

- The reason why the Government has invested so much in the project;

- The difficulties the researchers have faced.

- Make up an abstract of the article (6 – 8 sentences).

IV. Discussion. Preliminary work. Find out more about the possible non-military laser uses.

Discussion topic. "We never intended to spend $5 billion to $6 billion to build a laser facility for civilian research''. Would you personally intend to do that if you were a senator? Which is more important, civilian or military research? Give your reasons.

Date: 2015-01-02; view: 1118

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