by Staff Writers
Bochum, Germany (SPX) Nov 02, 2011
Electrical engineers in Bochum have succeeded in developing a new concept for ultrafast semiconductor lasers. The researchers make clever use of the intrinsic angular momentum of electrons, called spin, to successfully break the previous speed barriers.
The new spin lasers have the potential to achieve modulation frequencies of well above 100 GHz in future.
This is a decisive step towards high-speed data transmission, e.g. for the Internet of tomorrow. The researchers report on their results in the prestigious journal Applied Physics Letters of the American Institute of Physics.
Optical data transmission: the basis of our information society
The ever increasing degree of networking and the desire to exchange larger amounts of data are the driving force behind the development of ever faster optical data transmission systems.
The maximum speed of conventional semiconductor lasers has long been a limiting factor - typical modulation frequencies are currently at levels well below 50 GHz.
Over 100 GHz possible: a barrier collapses
By injecting these spin-polarised electrons, the laser is forced to work simultaneously on two laser modes with different frequencies.
"This frequency difference can easily be tuned using the so-called birefringence in the resonator, for example by simply bending the microlaser" said Dr. Nils Gerhardt. By coupling the two laser modes in the microresonator, oscillation with a new frequency occurs, which can theoretically reach well over 100 GHz.
The researchers around Dr. Gerhardt obtained their results in the collaborative research centre 491 of the Universities of Bochum and Duisburg-Essen ("Magnetic Heterostructures: Spin Structure and Spin Transport").
N.C. Gerhardt, M.Y. Li, H. Jahme, H. Hopfner, T. Ackemann, and M.R. Hofmann: "Ultrafast spin-induced polarization oscillations with tunable lifetime in vertical-cavity surface-emitting lasers", Appl. Phys. Lett. 99, 151107 (2011), DOI: 10.1063/1.3651339
Space Technology News - Applications and Research
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High-quality white light produced by four-color laser source
Albuquerque, NM (SPX) Nov 01, 2011
The human eye is as comfortable with white light generated by diode lasers as with that produced by increasingly popular light-emitting diodes (LEDs), according to tests conceived at Sandia National Laboratories. Both technologies pass electrical current through material to generate light, but the simpler LED emits lights only through spontaneous emission. Diode lasers bounce light back an ... read more
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