Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

TU Vienna develops light transistor

08.07.2013
TU Vienna has managed to turn the oscillation direction of beams of light – simply by applying an electrical current to a special material. This way, a transistor can be built that functions with light instead of electrical current.

Light can oscillate in different directions, as we can see in the 3D cinema: Each lens of the glasses only allows light of a particular oscillation direction to pass through. However, changing the polarization direction of light without a large part of it being lost is difficult.


The oscillation direction of a light wave is changed as it passes through a thin layer of a special material.

The TU Vienna has now managed this feat, using a type of light – terahertz radiation – that is of particular technological importance. An electrical field applied to an ultra-thin layer of material can turn the polarisation of the beam as required. This produces an efficient transistor for light that can be miniaturised and used to build optical computers.

Rotated light – the Faraday effect

Certain materials can rotate the polarization direction of light if a magnetic field is applied to them. This is known as the Faraday effect. Normally, this effect is minutely small, however. Two years ago, Prof. Andrei Pimenov and his team at the Institute of Solid State Physics of TU Vienna, together with a research group from the University of Würzburg, managed to achieve a massive Faraday effect as they passed light through special mercury telluride platelets and applied a magnetic field.

At that time, the effect could only be controlled by an external magnetic coil, which has severe technological disadvantages. "If electro-magnets are used to control the effect, very large currents are required", explains Andrei Pimenov. Now, the turning of terahertz radiation simply by the application of an electrical potential of less than one volt has been achieved. This makes the system much simpler and faster.

It is still a magnetic field that is responsible for the fact that the polarisation is rotated, however, it is no longer the strength of the magnetic field that determines the strength of the effect, but the amount of electrons involved in the process, and this amount can be regulated simply by electrical potential. Hence only a permanent magnet and a voltage source suffice, which is technically comparatively easy to manage.

Terahertz radiation
The light used for the experiments is not visible: it is terahertz radiation with a wavelength of the order of one millimetre. "The frequency of this radiation equates to the clock frequency that the next but one generation of computers may perhaps achieve", explains Pimenov. "The components of today's computers, in which information is passed only in the form of electrical currents, cannot be fundamentally improved. To replace these currents with light would open up a range of new opportunities." It is not only in hypothetical new computers that it's important to be able to control beams of radiation precisely with the newly developed light turning mechanism: terahertz radiation is used today for many purposes, for example for imaging methods in airport security technology.
Optical transistors
If light is passed through a polarisation filter, dependent on the polarisation direction, it is either allowed to pass through or is blocked. The rotation of the beam of light (and thus the electrical potential applied) therefore determines whether a light signal is sent or blocked. "This is the very principle of a transistor", explains Pimenov: "The application of an external voltage determines whether current flows or not, and in our case, the voltage determines whether the light arrives or not." The new invention is therefore the optical equivalent of an electrical transistor.
Further Information:
Prof. Andrei Pimenov
Institute of Solid State Physics
Vienna University of Technology
Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
T: +43-1-58801-137 23
andrei.pimenov@tuwien.ac.at

Florian Aigner | EurekAlert!
Further information:
http://www.tuwien.ac.at

More articles from Physics and Astronomy:

nachricht New type of smart windows use liquid to switch from clear to reflective
14.12.2017 | The Optical Society

nachricht New ultra-thin diamond membrane is a radiobiologist's best friend
14.12.2017 | American Institute of Physics

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

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

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Plasmonic biosensors enable development of new easy-to-use health tests

14.12.2017 | Health and Medicine

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>