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!
Basque researchers turn light upside down
23.02.2018 | Elhuyar Fundazioa
Attoseconds break into atomic interior
23.02.2018 | Max-Planck-Institut für Quantenoptik
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy