Featured Research

from universities, journals, and other organizations

Light transistor: Efficient transistor for light could lead to optical computers

Date:
July 8, 2013
Source:
Vienna University of Technology, TU Vienna
Summary:
Light can oscillate in different directions, as we can see in the 3-D 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. Scientists have now managed this feat, using a type of light – terahertz radiation – that is of particular technological importance.

The oscillation direction of a light wave is changed as it passes through a thin layer of a special material.
Credit: Image courtesy of Vienna University of Technology, TU Vienna

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 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.

Related Articles


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.


Story Source:

The above story is based on materials provided by Vienna University of Technology, TU Vienna. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. Shuvaev, A. Pimenov, G. V. Astakhov, M. Mühlbauer, C. Brüne, H. Buhmann, L. W. Molenkamp. Room temperature electrically tunable terahertz Faraday effect. Applied Physics Letters, 2013; 102 (24): 241902 DOI: 10.1063/1.4811496

Cite This Page:

Vienna University of Technology, TU Vienna. "Light transistor: Efficient transistor for light could lead to optical computers." ScienceDaily. ScienceDaily, 8 July 2013. <www.sciencedaily.com/releases/2013/07/130708102927.htm>.
Vienna University of Technology, TU Vienna. (2013, July 8). Light transistor: Efficient transistor for light could lead to optical computers. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2013/07/130708102927.htm
Vienna University of Technology, TU Vienna. "Light transistor: Efficient transistor for light could lead to optical computers." ScienceDaily. www.sciencedaily.com/releases/2013/07/130708102927.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) — Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) — What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) — A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) — The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins