Researchers control properties of light using nanostructures

March 8, 2016, University of the Basque Country

A theoretical study based on computational simulations conducted by the UPV/EHU's Nano-bio Spectroscopy Research Group in collaboration with the Japanese research centre AIST has shown that the intensity of ultraviolet light that is made to pass through a graphene nano-ribbon is modulated with a terahertz frequency. So we are seeing the opening up of a new field of research into obtaining terahertz radiation that has a whole host of applications. The research has been published in the prestigious journal Nanoscale.

The UPV/EHU's Nano-bio Spectroscopy Research Group led by Ángel Rubio, a UPV/EHU professor in the Department of Materials Physics and director of the Max Planck Institute for Structure and Dynamics of Matter in Hamburg, has simulated the conversion of into radiation in the terahertz range by passing it through a graphene nano-ribbon, and has developed a new compact device designed to generate radiation of this type based on the phenomenon discovered. The research, conducted in collaboration with the research group led by Yoshiyuki Miyamoto of the National Institute of Advanced Industrial Science and Technology (AIST) of Japan, has appeared in the prestigious journal Nanoscale, published by the Royal Society of Chemistry (United Kingdom).

Low-frequency has a broad range of applications, such as the characterisation of molecules, materials, tissues, etc. However, right now it is difficult to manufacture small, efficient, low-cost devices to produce terahertz radiation. This phenomenon "extends the range of applicability of radiation of this type to many other spheres in which it was not being used," explained Ángel Rubio, "owing to the fact that one would have to resort to much bigger radiation sources."

The starting point of a new field of research

To carry out this simulation, they used graphene nano-ribbons: strips cut out of sheets of graphene. They concluded that UV light that exerts an effect on the nano-ribbon emits a totally different (terahertz) perpendicular to the incident light. This phenomenon "opens up the possibility of generating structures that will allow the frequency range to be changed using different nanostructures," explained Prof Rubio. "A new field of research is being opened up."

Now that the existence of the phenomenon has been demonstrated, "it would be necessary to see if the same thing can be done with a different type of light source," explained Ángel Rubio. In the research they used a high-intensity laser pointer so that the simulation would be correct, but it should be possible to use "more accessible sources," he said. In the future, another step would be "to use a set of nanostructures instead of a single one to produce an actual device."

The UPV/EHU developed the idea and its implementation in code that simulates the process on the computer, while the Japanese research centre AIST made the numerical calculations. The researchers have used novel simulation techniques of first principles—methods in which the predictive capacity is very high, with which the behaviour of a material is predicted without using external parameters. "The simulation techniques have reached a point," said Rubio, "where systems that are later shown to actually behave in the same way experimentally can be predicted."

The Nano-bio Spectroscopy Group is led by Ángel Rubio. The group's activity focuses on the theoretical research and modelling of electronic and structural properties of condensed matter as well as the development of new theoretical tools and computer codes to explore the electronic response of solids and nanostructures when handling external electromagnetic fields.

Explore further: Defective nanotubes turned into light emitters

More information: Hong Zhang et al. Optical field terahertz amplitude modulation by graphene nanoribbons, Nanoscale (2015). DOI: 10.1039/C5NR05889A

Related Stories

Defective nanotubes turned into light emitters

October 31, 2013

Scientists are usually after defect-free nano-structures. Yet in this case the UPV/EHU researcher Angel Rubio and his collaborators have put the structural defects in boron nitride nanotubes to maximum use. The outcome of ...

New device converts DC electric field to terahertz radiation

August 4, 2015

Terahertz radiation, the no-man's land of the electromagnetic spectrum, has long stymied researchers. Optical technologies can finagle light in the shorter-wavelength visible and infrared range, while electromagnetic techniques ...

A quantum of light for materials science

December 1, 2015

Computer simulations that predict the light-induced change in the physical and chemical properties of complex systems, molecules, nanostructures and solids usually ignore the quantum nature of light. Scientists of the Max-Planck ...

Metamaterials shine bright as new terahertz source

April 23, 2015

Metamaterials allow design and use of light-matter interactions at a fundamental level. An efficient terahertz emission from two-dimensional arrays of gold split-ring resonator metamaterials was discovered as a result of ...

Researchers mine the 'Terahertz gap'

February 4, 2008

Research underway at the University of Leeds will provide a completely fresh insight into the workings of nano-scale systems, and enable advances in the development of nano-electronic devices for use in industry, medicine ...

Recommended for you

Paleontologists report world's biggest Tyrannosaurus rex

March 22, 2019

University of Alberta paleontologists have just reported the world's biggest Tyrannosaurus rex and the largest dinosaur skeleton ever found in Canada. The 13-metre-long T. rex, nicknamed "Scotty," lived in prehistoric Saskatchewan ...

NASA instruments image fireball over Bering Sea

March 22, 2019

On Dec. 18, 2018, a large "fireball—the term used for exceptionally bright meteors that are visible over a wide area—exploded about 16 miles (26 kilometers) above the Bering Sea. The explosion unleashed an estimated 173 ...

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.