Boston College, New Mexico and Duke researchers advance THz imaging using unique metamaterial
A novel metamaterial enables a fast, efficient and high-fidelity terahertz radiation imaging system capable of manipulating the stubborn electromagnetic waves, advancing a technology with potential applications in medical and security imaging, a team led by Boston College researchers reports in the online edition of the journal Nature Photonics.
Developed by a team of researchers from Boston College, the University of New Mexico and Duke University, a "multiplex" single pixel imaging process effectively tames stubborn terahertz (THz) light waves with electronic controls in a novel metamaterial. As the graphic shows, THz image waves are received by a metamaterial spatial light modulator, which in turn sends multiple data points from the THz scene to a single-pixel detector, which computationally reconstructs the image faster, more efficiently and with higher-fidelity than conventional THz imaging technology. Credit: Nature Photonics
The team reports it developed a "multiplex" tunable spatial light modulator (SLM) that uses a series of filter-like "masks" to retrieve multiple samples of a terahertz (THz) scene, which are reassembled by a single-pixel detector, said Boston College Professor of Physics Willie Padilla, a lead author of the report.
Data obtained from these encoded measurements are used to computationally reconstruct the images as much as six times faster than traditional raster scan THz devices, the team reports. In addition, the device employs an efficient low power source, said Padilla, whose research team worked with colleagues from the University of New Mexico and Duke University.
"I think we were surprised by how well the imaging system worked, particularly in light of the incredibly low power source," said Padilla. "Traditional THz imaging systems use sources that demand much more power than our system."
Metamaterials are designer electromagnetic materials that have tunable optical properties, allowing them to interact with light waves in new ways. Those unique properties have proven conducive to working with THz light waves, which have longer wavelengths than visible light and therefore require new imaging technology.
Padilla said the team set out to use metamaterials to develop an imaging architecture superior to earlier THz camera designs, which have relied on expensive and bulky detector arrays to assemble images.
Central to the team's advanced device is the development of a spatial light modulator constructed from a unique metamaterial structure by researchers at the University of New Mexico's Center for High Technology Materials. The SLM, which deploys a series of masks to obtain select image information from the THz scene, showed it effectively tames the otherwise stubborn THz light waves, which have defied other forms of frequency controls such as electronic sensors and semiconductor devices.
The metamaterial SLM efficiently modulates THz radiation when an electronically controlled voltage is applied between two layers of the metamaterial, effectively changing its optical properties and allowing it to actively display encoding masks designed to retrieve THz images. One such encoding technique allowed the researchers to access negative encoding values, which allow for higher fidelity image reconstruction.
A negative encoding value typically requires phase-sensitive sources and detectors, multiple detectors, or taking twice the number of measurements in order to create the image. The team created its "masks" without additional equipment or measurements, allowing researchers to use a more robust image encoding method that increased image quality while reducing the time needed to acquire the image.
Since it offers improved results without additional equipment, researchers engaged in "multiplexing" THz imaging could quickly adopt the new imaging approach. The findings add to a growing body of research that shows metamaterials are a viable option for the construction of efficient SLMs at THz wavelengths.
"In the long run, I think we set out a new paradigm for imaging at longer wavelengths," said Padilla. "Rather than including an expensive and bulky detector array in an imaging system, high-fidelity images can be obtained with only a single pixel detector and a low power source, allowing for a compact and inexpensive THz imaging system."
Padilla said a new generation of metamaterial THz imaging systems could help realize the potential applications projected by researchers and theorists.
"This type of imaging system has the potential to make a huge impact," said Padilla. "The ability to image a scene with THz could be used to screen for cancerous skin cells, monitor airports and other secure areas for illegal drugs or explosives, and perform personnel screening to look for concealed weapons."
In addition to Padilla, the research team included BC graduate students Claire M. Watts and David Shrenkenhamer and undergraduate Timothy Sleasman; University of New Mexico Professor Sanjay Krishna and graduate students; and Duke University Professor David R. Smith and graduate students, of the Center for Metamaterials and Integrated Plasmonics.
Ed Hayward | Eurek Alert!
Researchers devise microreactor to study formation of methane hydrate
23.08.2017 | NYU Tandon School of Engineering
Meter-sized single-crystal graphene growth becomes possible
22.08.2017 | Science China Press
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
23.08.2017 | Life Sciences
23.08.2017 | Life Sciences
23.08.2017 | Physics and Astronomy