Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

What a twist: Silicon nanoantennas turn light around

16.11.2016

The theoretical results will allow scientists to design nanodevices with extraordinary features for use in optoelectronics

A team of physicists from ITMO University, MIPT, and The University of Texas at Austin have developed an unconventional nanoantenna that scatters light in a particular direction depending on the intensity of incident radiation. The research findings will help with the development of flexible optical information processing in telecommunication systems.


Fig. 1. An artist's rendering of nonlinear light scattering by a dimer of two silicon particles with a variable radiation pattern.

Image courtesy of the press office of MIPT

Photons--the carriers of electromagnetic radiation--have neither mass nor electric charge. This means that light is relatively hard to control, unlike, for example, electrons: their flow in electronic circuits can be controlled by applying a constant electric field. However, such devices as nanoantennas enable a certain degree of control over the propagation of electromagnetic waves.

One area that requires the "advanced" light manipulation is the development of optical computers. In these devices, the information is carried not by electrons, but by photons. Using light instead of charged particles has the potential to greatly improve the speed of transmitting and processing information. To make these computers a reality, we need specific nanoantennas with characteristics that can be manipulated in some way--by applying a constant electric or magnetic field, for instance, or by varying the intensity of incident light.

In the paper published in Laser & Photonics Reviews, the researchers designed a novel nonlinear nanoantenna that can change the direction of light scattering depending on the intensity of the incident wave (Fig. 1). At the heart of the proposed nanoantenna are silicon nanoparticles, which generate electron plasma under harsh laser radiation.

The authors previously demonstrated the possibilities of using these nanoparticles for the nonlinear and ultrafast control of light. The researchers then managed to manipulate portions of light radiation scattered forward and backward. Now, by changing the intensity of incident light, they have found a way to turn a scattered light beam in the desired direction.

To rotate the radiation pattern of the nanoantenna, the authors used the mechanism of plasma excitation in silicon. The nanoantenna is a dimer--two silicon nanospheres of unequal diameters. Irradiated with a weak laser beam, this antenna scatters the light sideways due to its asymmetric shape (blue diagram in Fig. 2A). The diameters of the two nanoparticles are chosen so that one particle is resonant at the wavelength of the laser light. Irradiated with an intense laser pulse, electron plasma is generated in the resonant particle which causes changes in the optical properties of the particle.

The other particle remains nonresonant, and the powerful laser field has little effect on it. Generally speaking, by accurately choosing the relative size of both particles in combination with the parameters of the incident beam (duration and intensity), it is possible to make the size of the particles virtually the same, which enables the antenna to bounce the light beam forward (red diagram in Fig. 2a).

"Existing optical nanoantennas can control light in a fairly wide range. However, this ability is usually embedded in their geometry and the materials they are made of, so it is not possible to configure these characteristics at any time," says Denis Baranov, a postgraduate student at MIPT and the lead author of the paper. "The properties of our nanoantenna, however, can be dynamically modified. When we illuminate it with a weak laser impulse, we get one result, but with a strong impulse, the outcome is completely different."

The scientists performed numerical modeling of the light scattering mechanism, Fig. 2b. The simulation showed that when the nanoantenna is illuminated with a weak laser beam, the light scatters sideways. However, if the nanoantenna is illuminated with an intense laser impulse, that leads to the generation of electron plasma within the device and the scattering pattern rotates by 20 degrees (red line). This provides an opportunity to deflect weak and strong incident impulses in different directions.

Sergey Makarov, a senior researcher at the Department of Nanophotonics and Metamaterials at ITMO University concludes: "In this study, we focused on the development of a nanoscale optical chip measuring less than 200×200×500 nanometers. This is much less than the wavelength of a photon, which carries the information. The new device will allow us to change the direction of light propagation at a much better rate compared to electronic analogues. Our device will be able to distribute a signal into two optical channels within a very short space of time, which is extremely important for modern telecommunication systems."

Today, information is transmitted via optical fibers at speeds of up to hundreds of Gbit/s. However, even modern electronic devices process these signals quite slowly: at speeds of only a few Gbit/s for a single element. The proposed nonlinear optical nanoantenna can solve this problem, as it operates at 250 Gbit/s. This paves the way for ultrafast processing of optical information. The nonlinear antenna developed by the researchers provides more opportunities to control light at nanoscale, which is what is required in order to successfully develop photonic computers and other similar devices.

Nicolas Posunko | EurekAlert!

More articles from Physics and Astronomy:

nachricht Two dimensional circuit with magnetic quasi-particles
22.01.2018 | Technische Universität Kaiserslautern

nachricht Meteoritic stardust unlocks timing of supernova dust formation
19.01.2018 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>