Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chaos in the microlaser

22.06.2011
Würzburg physicists have created a microlaser with unique properties. They have also succeeded in making the laser behave chaotically. In the future, it may be possible to use this for a new, secure form of data transmission.

Triggering chaotic behavior in the microcosm: this is what Stephan Reitzenstein and his team from the Institute of Physics at the University of Würzburg have achieved in collaboration with their Israeli colleague Ido Kanter, as reported on in the latest issue of the journal “Nature Communications”. Using a tiny laser, the researchers continually sent a fraction of the emitted light back into the laser, throwing the light emission process “out of kilter”. The microlaser then started emitting light particles (photons) in a chaotic pulse sequence.


A quantum-dot microlaser emits light that is deliberately cast back into the laser via a mirror. This disturbs the laser’s operation so much so that the emission behavior becomes chaotic. On the right, the result of a photon statistics measurement from which physicists are able to detect a chaotic pulse sequence, given that without chaos no pulses would appear. Image: Ferdinand Albert

“This chaos is extremely interesting from a fundamental physics point of view,” explains Reitzenstein. But the targeted feedback also offers application possibilities, he adds. “It might be used in the future for optical amplifiers and switches. In addition, the negative feedback of two microlasers over a long distance is likely to provide synchronization of the chaotic pulse sequence, enabling the realization of a new, secure form of data transmission.”

Microlasers made in Würzburg

The microlasers are made using a sophisticated procedure in the microstructure laboratory of the Institute of Physics at Würzburg. They look like tiny towers with a diameter of less than a tenth of a human hair, and they consist of a special sequence of extremely thin semiconductor layers. They are driven electrically using an elaborately designed ring contact.

During production, special nanostructures that can emit light – so-called quantum dots – are placed in the center of the microlasers. What makes them special? “The microlasers have been designed such that the photons emitted by the quantum dots are coupled into the lasing mode with extremely high probability and can therefore be used for very efficient laser operation,” as Reitzenstein says.

Close to the ultimate model

On account of their special design, the Würzburg microlasers can be driven with no more than a few microamperes and only around ten quantum dots. In conventional semiconductor lasers, on the other hand, pump currents in the milliampere range as well as some 1,000 to 10,000 quantum dots are needed.

“Intensive research is being conducted worldwide in order to create the ‘ultimate’ micro- or nanolaser that only contains a single quantum dot as a gain medium,” explains Reitzenstein. The Würzburg physicists have now come very close to this goal with their model.

Chaotic pulse sequence produced

Such highly sophisticated quantum dot microlasers react very sensitively to fluctuations in the quantity of light particles in the laser resonator. Even the emission of a single photon can throw the laser’s operation into confusion. The scientists turned the tables and cast the emitted light back onto the microlaser with a mirror continuously, precisely, and in a controlled fashion in order to disturb its operation.

It transpired that if the lasers emit only a few tens of nanowatts of light power, the influence of the feedback cannot be measured directly. “Instead, complex photon statistics measurements are needed to prove the expected chaotic behavior,” says Reitzenstein. But here the physicists achieved success: they were able to prove that disturbing the laser leads to a chaotic pulse sequence in which each light pulse contains only around 100 photons.

Next steps in the research

“We are currently preparing experiments to synchronize two lasers as far as the quantum limit of just one photon moving back and forth,” says Reitzenstein. “If we succeed, we will be a step closer to a fundamental understanding of synchronization and to a secure form of data transmission.”

There is also another hurdle to negotiate: at present, the microlasers only work in extremely cold conditions, at below minus 150 degrees Celsius. Operation at room temperature should be possible, however, if the quantum dots are optimized for this purpose. The physicists are currently pursuing this goal in a separate project.

“Observing chaos for quantum-dot microlasers with external feedback”, Ferdinand Albert, Caspar Hopfmann, Stephan Reitzenstein, Christian Schneider, Sven Höfling, Lukas Worschech, Martin Kamp, Wolfgang Kinzel, Alfred Forchel & Ido Kanter, Nature Communications, doi 10.1038/ncomms1370

Contact

Dr. Stephan Reitzenstein, Institute of Physics at the University of Würzburg,
T +49 (0)931 31-85116, stephan.reitzenstein@physik.uni-wuerzburg.de

Robert Emmerich | idw
Further information:
http://www.uni-wuerzburg.de

More articles from Physics and Astronomy:

nachricht Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>