The discovery may help develop noninvasive imaging and sensing, and make possible THz-speed information communication, processing and storage. The results appeared in the Jan. 8 issue of Nature Communications.
A THz spectrometer driven by femtosecond laser pulses was used to demonstrate THz emission from a split-ring resonator metamaterial
of single nanometer thickness.
Terahertz electromagnetic waves occupy a middle ground between electronics waves, like microwave and radio waves, and photonics waves, such as infrared and UV waves. Potentially, THz waves may accelerate telecom technologies and break new ground in understanding the fundamental properties of photonics. Challenges related to efficiently generating and detecting THz waves has primarily limited their use.
Traditional methods seek to either compress oscillating waves from the electronic range or stretch waves from the optical range. But when compressing waves, the THz frequency becomes too high to be generated and detected by conventional electronic devices. So, this approach normally requires either a large-scale electron accelerator facility or highly electrically-biased photoconductive antennas that produce only a narrow range of waves.
To stretch optical waves, most techniques include mixing two laser frequencies inside an inorganic or organic crystal. However, the natural properties of these crystals result in low efficiency.
So, to address these challenges, the Ames Laboratory team looked outside natural materials for a possible solution. They used man-made materials called metamaterials, which exhibit optical and magnetic properties not found in nature.
Costas Soukoulis, an Ames Laboratory physicist and expert in designing metamaterials, along with collaborators at Karlsruhe Institute of Technology in Germany, created a metamaterial made up of a special type of meta-atom called split-ring resonators. Split-ring resonators, because of their u-shaped design, display a strong magnetic response to any desired frequency waves in the THz to infrared spectrum.
Ames Laboratory physicist Jigang Wang, who specializes in ultra-fast laser spectroscopy, designed the femto-second laser experiment to demonstrate THz emission from the metamaterial of a single nanometer thickness.
“The combination of ultra-short laser pulses with the unique and unusual properties of the metamaterial generates efficient and broadband THz waves from emitters of significantly reduced thickness,” says Wang, who is also an associate professor of Physics and Astronomy at Iowa State University.
The team demonstrated their technique using the wavelength used by telecommunications (1.5 microns), but Wang says that the THz generation can be tailored simply by tuning the size of the meta-atoms in the metamaterial.
“In principle, we can expand this technique to cover the entire THz range,” said Soukoulis, who is also a Distinguished Professor of physics and astronomy at Iowa State University.
What’s more, the team’s metamaterial THz emitter measured only 40 nanometers and performed as well as traditional emitters that are thousands of times thicker.
“Our approach provides a potential solution to bridge the ‘THz technology gap’ by solving the four key challenges in the THz emitter technology: efficiency; broadband spectrum; compact size; and tunability,” said Wang.
Soukoulis, Wang, Liang Luo and Thomas Koschny's work at Ames Laboratory was supported by the U.S. Department of Energy's Office of Science. Wang's work is partially supported by Ames Laboratory’s Laboratory Directed Research and Development (LDRD) funding.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.
Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.
Breehan Gerleman Lucchesi | EurekAlert!
Suzaku, Herschel link a black-hole 'wind' to a galactic gush of star-forming gas
26.03.2015 | NASA/Goddard Space Flight Center
Tiny Bio-Robot Is a Germ Suited-Up with Graphene Quantum Dots
25.03.2015 | University of Illinois at Chicago
In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...
The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.
As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...
When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.
The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe.
Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...
Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.
From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...
25.03.2015 | Event News
19.03.2015 | Event News
17.03.2015 | Event News
26.03.2015 | Trade Fair News
26.03.2015 | Trade Fair News
26.03.2015 | Life Sciences