They have shown that it is possible for light (electromagnetic waves) to propagate from point A to point B without accumulating any phase, spreading through the artificial medium as if the medium is completely missing in space. This is the first time simultaneous phase and zero-index observations have been made on the chip-scale and at the infrared wavelength.
The study, to be published on Nature Photonics's website July 10, was led by Chee Wei Wong, associate professor of mechanical engineering, and Serdar Kocaman, electrical engineering PhD candidate, both at Columbia Engineering, in collaboration with scientists at the University College of London, Brookhaven National Laboratory, and the Institute of Microelectronics of Singapore.
"We're very excited about this. We've engineered and observed a metamaterial with zero refractive index," said Kocaman. "What we've seen is that the light disperses through the material as if the entire space is missing. The oscillatory phase of the electromagnetic wave doesn't even advance such as in a vacuum — this is what we term a zero-phase delay."
This exact control of optical phase is based on a unique combination of negative and positive refractive indices. All natural known materials have a positive refractive index. By sculpturing these artificial subwavelength nanostructures, the researchers were able to control the light dispersion so that a negative refractive index appeared in the medium. They then cascaded the negative index medium with a positive refractive index medium so that the complete nanostructure behaved as one with an index of refraction of zero.
"Phase control of photons is really important," said Wong. "This is a big step forward in figuring out how to carry information on photonic chips without losing control of the phase of the light."
"We can now control the flow of light, the fastest thing known to us," he continued. "This can enable self-focusing light beams, highly directive antennas, and even potentially an approach to cloak or hide objects, at least in the small-scale or a narrow band of frequencies currently."
This research was supported by grants from the National Science Foundation and the Defense Advanced Research Projects Agency.
Columbia University's Fu Foundation School of Engineering and Applied Science, founded in 1864, offers programs in nine departments to both undergraduate and graduate students. With facilities specifically designed and equipped to meet the laboratory and research needs of faculty and students, Columbia Engineering is home to major Centers in energy, nanoscience, optics, genomic science, materials science, as well as one of the world's leading programs in financial engineering. These interdisciplinary centers are leading the way in their respective fields while individual groups of engineers and scientists collaborate to solve some of society's more vexing challenges. http://www.engineering.columbia.edu/
'Frequency combs' ID chemicals within the mid-infrared spectral region
16.03.2018 | American Institute of Physics
Fraunhofer HHI have developed a novel single-polarization Kramers-Kronig receiver scheme
16.03.2018 | Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, HHI
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences