Wednesday, November 2, 2011

Ultrafast Semiconductor Lasers for High-Speed Optical Data Transmission

Ruhr-Universität Bochum (RUB) researchers have conceptualized an ultrafast semiconductor laser to enable high-speed data transmission over the Internet. They have utilized the spin of electrons and their intrinsic angular momentum for overcoming the existing limits to modulation speed. 


 The global information society and the networked world require semiconductor laser-based optical data transmission. The highest speed achievable by semiconductor lasers has limited the speed of optical data transmission. The desire for transmitting higher volume of data and expanding networks have been the motivation for the development of faster transmission systems.

Current modulation frequencies of conventional semiconductor lasers are lower than 50 GHz. RUB researchers have used spin lasers for overcoming the modulation speed limits. In spin lasers, electrons whose spin state has already been determined are injected, but in conventional lasers the electrons’ spin is arbitrary.

The injection of the spin-polarized electrons forces the laser to work with different frequencies in two laser modes. Dr. Nils Gerhardt stated that the birefringence in the resonator can be used to tune the differences in the frequencies. This could be done by bending the microlaser. Coupling of the two laser modes within the microresonator leads to an oscillation with a frequency of over 100 GHz, theoretically.

The study has been conducted at the collaborative research centre 491 at the Universities of Bochum and Duisburg-Essen. The research has been published in the Applied Physics Letters journal from the American Institute of Physics.


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