Featured Research

from universities, journals, and other organizations

Engineers Tune A Nanoscale Grating Structure To Trap And Release A Variety Of Light Waves

Date:
February 28, 2009
Source:
Lehigh University
Summary:
Researchers have developed a graded grating structure that can be scaled to dimensions compatible with light waves in both the terahertz and telecommunications portion of the spectrum. The achievement opens the door to the control of light waves on a chip. It has applications in spectroscopy, sensing and medical imaging, and it could hasten the arrival of all-optical telecommunication networks.

People debating politics are well-advised to shed more light than heat. Engineers working in optical technologies have the same aspiration.

Related Articles


Light waves transmit data with much greater speed than do electrical signals, says Qiaoqiang Gan, a Ph.D. candidate at Lehigh University in Bethlehem, Pa. If they are guided with sufficient precision inside the tiny circuits of an electronic chip, they can bring about applications in spectroscopy, sensing and medical imaging. And they can hasten the advent of faster all-optical telecommunication networks, in which light signals transmit and route data without needing to be converted to electrical signals and back.

To enable light waves to store and transmit data with optimal efficiency, engineers must learn to slow or stop light waves across the various regions of the spectrum.

Gan and his adviser, Filbert J. Bartoli, department chair of electrical and computer engineering, made a major contribution to this effort last year when they developed a graded metal grating structure capable of slowing or stopping terahertz (THz) light waves. The achievement, said Bartoli, "opened a door to the control of light waves on a chip" that could help reduce the size of optical structures, enabling them to be integrated at the nanoscale with electronic devices.

Gan and Bartoli reported their results in June in Physical Review Letters (PRL). Their article was coauthored by Yujie J. Ding, professor of electrical and computer engineering, and Zhan Fu, a Ph.D. candidate advised by Ding. The researchers are affiliated with Lehigh's Center for Optical Technologies.

Recently, Bartoli's team recorded a second major advance. Working again with Ding, they demonstrated that their grating structure could be scaled down in size to a dimension compatible with light waves in the telecommunications portion of the spectrum.

THz waves measure several hundred microns in length (1 micron is one-millionth of a meter) and are suitable for security applications. Wavelengths in the telecommunications range of the spectrum measure 1330 to 1550 nanometers (1 nm is one-billionth of a meter) and are suitable for optical communications.

The three researchers reported their progress in a second PRL article, titled "Rainbow Trapping and Releasing at Telecommunication Wavelengths." The article was published in the journal's Feb. 6 issue.

In the current article, the researchers also address a phenomenon called loss in metals, in which the metal materials of a chip, instead of simply propagating light, also absorb it and dissipate it as heat. Metal loss occurs more strongly with telecommunications light waves than with THz light waves.

To use trapped light waves for telecommunications, says Gan, it is necessary to release them from the grating structure. Gan and his colleagues accomplished this by covering the structure with dielectric materials.

"By tuning the temperature of the dielectric materials, we were able to change the optical properties of the metal grating structure," he said. "This in turn enabled the trapped light waves to be released."

The Lehigh researchers describe their structure as a "metallic grating structure with graded depths, whose dispersion curves and cutoff frequencies are different at different locations." In appearance, the grating resembles the pipes of a pipe organ arranged side by side and decreasing gradually in length from one end of the assembly to the other. The degree of grade in the grating can be tuned by altering the temperature and modifying the physical features on the surface of the structure.

The structure arrests the progress of light waves at multiple locations on the surface and at different frequencies. Previous researchers, Gan says, had been able "to slow down one single wavelength within a narrow bandwidth, but not many wavelengths over a wide spectrum."

Most of the initial work on this project has been theoretical, using mathematical equations and computer simulation. Bartoli's group has now moved to the next stage, which includes fabricating and characterizing the structures.

"It will be challenging," Gan says, "to achieve a grade of grating depths which range from very shallow to as much as 50 nanometers on a 200-nm substrate. To do this, we are using the focused ion beam milling facilities in the materials science and engineering department. We have already fabricated many structures and will now try to characterize the graded gratings with near-field scanning optical microscopy in Prof. Volkmar Dierolf's lab in the physics department.

"We are pursuing promising applications based on these structures. These include biosensing and bioimaging."

An article in the Feb. 14 issue of the British journal New Scientist said the results obtained by Bartoli's team "suggest that one day we might be able to slow down light long enough to store it as a 'rainbow' or colors – an advance that would revolutionize computing and telecommunication networks."

Light is stored for a few pico-seconds in the grating structure, the New Scientist article notes. But this, according to physicist Ortwin Hess of the University of Surrey in the United Kingdom, "is quite significant for many applications."


Story Source:

The above story is based on materials provided by Lehigh University. Note: Materials may be edited for content and length.


Cite This Page:

Lehigh University. "Engineers Tune A Nanoscale Grating Structure To Trap And Release A Variety Of Light Waves." ScienceDaily. ScienceDaily, 28 February 2009. <www.sciencedaily.com/releases/2009/02/090217125546.htm>.
Lehigh University. (2009, February 28). Engineers Tune A Nanoscale Grating Structure To Trap And Release A Variety Of Light Waves. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2009/02/090217125546.htm
Lehigh University. "Engineers Tune A Nanoscale Grating Structure To Trap And Release A Variety Of Light Waves." ScienceDaily. www.sciencedaily.com/releases/2009/02/090217125546.htm (accessed October 30, 2014).

Share This



More Matter & Energy News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Mind-Controlled Prosthetic Arm Restores Amputee Dexterity

Mind-Controlled Prosthetic Arm Restores Amputee Dexterity

Reuters - Innovations Video Online (Oct. 29, 2014) A Swedish amputee who became the first person to ever receive a brain controlled prosthetic arm is able to manipulate and handle delicate objects with an unprecedented level of dexterity. The device is connected directly to his bone, nerves and muscles, giving him the ability to control it with his thoughts. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Robots Get Funky on the Dance Floor

Robots Get Funky on the Dance Floor

AP (Oct. 29, 2014) Dancing, spinning and fighting robots are showing off their agility at "Robocomp" in Krakow. (Oct. 29) Video provided by AP
Powered by NewsLook.com
Saharan Solar Project to Power Europe

Saharan Solar Project to Power Europe

Reuters - Business Video Online (Oct. 29, 2014) A solar energy project in the Tunisian Sahara aims to generate enough clean energy by 2018 to power two million European homes. Matt Stock reports. Video provided by Reuters
Powered by NewsLook.com
Lowe's Testing Robot Sales Assistants in California Store

Lowe's Testing Robot Sales Assistants in California Store

Buzz60 (Oct. 29, 2014) Lowe’s is testing out what it’s describing as a robotic shopping assistant in one of its Orchard Supply Hardware Stores in California. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins