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.
Florian Aigner | EurekAlert!
Streamlining accelerated computing for industry
24.08.2016 | DOE/Oak Ridge National Laboratory
Lehigh engineer discovers a high-speed nano-avalanche
24.08.2016 | Lehigh University
Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...
Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.
In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...
Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.
Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...
Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...
A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.
25.08.2016 | Event News
24.08.2016 | Event News
12.08.2016 | Event News
29.08.2016 | Materials Sciences
29.08.2016 | Life Sciences
29.08.2016 | Medical Engineering