Researchers create an innovative light-trapping nanostructure using a genetic-inspired approach
Physicists at the University of Rochester have created a silicon nanocavity that allows light to be trapped longer than in other similarly-sized optical cavities. An innovative design approach, which mimics evolutionary biology, allowed them to achieve a 10-fold improvement on the performance of previous nanocavities.
Light-trapping nanostructure created by the researchers: The top layer shows a simulation of the nanostructure confining the light in the tiny red regions. The second layer is the design generated by an approach that mimics evolutionary biology. The bottom two layers show electron micrographs of the realized nanostructure in silicon. The sharp peak on the left is the trace of the long trapping of light. Credit: Fabio Badolato
In a paper published in Applied Physics Letters today and featured on the cover, the scientists demonstrate they have confined light in a nanocavity – a nanostructured region of a silicon wafer – for nanoseconds. Typically light would travel several meters in that time, but instead the nanostructure confined light in a region no bigger than one one hundredth the width of a human hair – roughly one-half millionth of a meter.
“Light holds the key to some of nature’s deepest secrets, but it is very challenging to confine it in small spaces,” says Antonio Badolato, professor of physics at the University of Rochester and corresponding author of the Applied Physics Letters paper. “Light has no rest mass or charge that allow forces to act on it and trap it; it has to be done by carefully designing tiny mirrors that reflect light millions of times.”
Nanocavities are key components of nanophotonics circuits and Badolato explains that this new approach will help implement a new-generation of highly integrated nanophotonics structures.
Researchers are interested in confining light because it allows for easier manipulation and coupling to other devices. Trapping light also allows researchers to study it at its fundamental level, that is, at the state when light behaves as a particle (an area that led to the 2012 Nobel Prize in Physics).
Until now, researchers have been using educated-guess procedures to design the light-trapping nanostructures. However in this case, the team of researchers – which included lead author and Badolato’s Ph.D. student, Yiming Lai, and groups from the Ecole Polytechnique Federale de Lausanne, Switzerland, and the Universita di Pavia, Italy– perfected a numerical technique that lead to the design improvement. Their computational approach allowed them to search for the optimal combination of parameters among thousand of realizations using a “genetic” (or “evolutionary”) algorithm tool.
The principle behind the genetic approach is to regard each new nanocavity as an individual in a population. The individuals mutate and “breed,” meaning that two single structures combine to create a new one that is a cross between the two “parents.” As new generations succeeded one another, the algorithm selected the fittest ones in each generation, in this case, the ones that exhibited the longest trapping time (i.e. highest quality factor).
Integrated nanophotonics is a new and rapidly growing field of research laying at the intersection of photonics, nanotechnology, and materials science. In the near future, nanophotonics circuits will enable disruptive technologies ranging from telecommunications to biosensing, and because they can process pulses of light extremely fast and with very low energy consumption, they hold the potential to replace conventional information-handling systems.
The results shown by Badolato and his colleagues demonstrate one of the highest quality factors ever measured in nanocavities while maintaining a very small footprint. By keeping the nanocavities so small while trapping light so efficiently it becomes possible to create devices with ultra-dense integration – a desired characteristic in the fabrication of optical nanocircuits.
The extreme sensitivity of these nanocavities to tiny changes in the environment, for example a virus attaching near the area where light is trapped, makes these devices particularly appealing for biosensing. By using these highly sensible nanocavities, such a biosensing device could detect minute quantities of these biomaterials by analyzing a single drop of blood. Badolato’s group is now starting a collaboration with researchers at the University of Rochester’s Medical Center to exploit this interesting property with the new nanocavities.
Y. Lai, S. Pirotta, G. Urbinati, D. Gerace, M. Minkov, V. Savona, A. Badolato, M. Galli. Genetically designed L3 photonic crystal nanocavities with measured quality factor exceeding one million.
Leonor Sierra | Eurek Alert!
Tracing aromatic molecules in the early universe
23.03.2017 | University of California - Riverside
New study maps space dust in 3-D
23.03.2017 | DOE/Lawrence Berkeley National Laboratory
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences