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!
Stellar desk in wave-like motion
08.10.2015 | Max Planck Institute for Astronomy, Heidelberg
Mysterious ripples found racing through planet-forming disk
08.10.2015 | NASA/Goddard Space Flight Center
Nondestructive material testing (NDT) is a fast and effective way to analyze the quality of a product during the manufacturing process. Because defective materials can lead to malfunctioning finished products, NDT is an essential quality assurance measure, especially in the manufacture of safety-critical components such as automotive B-pillars. NDT examines the quality without damaging the component or modifying the surface of the material. At this year's Blechexpo trade fair in Stuttgart, Fraunhofer IZFP will have an exhibit that demonstrates the nondestructive testing of high-strength automotive body parts using 3MA. The measurement results are available in a matter of seconds.
To minimize vehicle weight and fuel consumption while providing the highest level of crash safety, automotive bodies are reinforced with elements made from...
The MICADO camera, a first light instrument for the European Extremely Large Telescope (E-ELT), has entered a new phase in the project: by agreeing to a Memorandum of Understanding, the partners in Germany, France, the Netherlands, Austria, and Italy, have all confirmed their participation. Following this milestone, the project's transition into its preliminary design phase was approved at a kick-off meeting held in Vienna. Two weeks earlier, on September 18, the consortium and the European Southern Observatory (ESO), which is building the telescope, have signed the corresponding collaboration agreement.
As the first dedicated camera for the E-ELT, MICADO will equip the giant telescope with a capability for diffraction-limited imaging at near-infrared...
Self-driving cars will be on our streets in the foreseeable future. In Graz, research is currently dedicated to an innovative driver assistance system that takes over control if there is a danger of collision. It was nature that inspired Dr Manfred Hartbauer from the Institute of Zoology at the University of Graz: in dangerous traffic situations, migratory locusts react around ten times faster than humans. Working together with an interdisciplinary team, Hartbauer is investigating an affordable collision detector that is equipped with artificial locust eyes and can recognise potential crashes in time, during both day and night.
Inspired by insects
An interdisciplinary team of researchers has built the first prototype of a miniature particle accelerator that uses terahertz radiation instead of radio...
At present, tiny magnetic whirls – so called skyrmions – are discussed as promising candidates for bits in future robust and compact data storage devices. At...
01.10.2015 | Event News
30.09.2015 | Event News
17.09.2015 | Event News
09.10.2015 | Earth Sciences
09.10.2015 | Life Sciences
09.10.2015 | Life Sciences