%0 Journal Article
%T Spin-Controlled Vertical-Cavity Surface-Emitting Lasers
%A Nils C. Gerhardt
%A Martin R. Hofmann
%J Advances in Optical Technologies
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/268949
%X We discuss the concept of spin-controlled vertical-cavity surface-emitting lasers (VCSELs) and analyze it with respect to potential room-temperature applications in spin-optoelectronic devices. Spin-optoelectronics is based on the optical selection rules as they provide a direct connection between the spin polarization of the recombining carriers and the circular polarization of the emitted photons. By means of optical excitation and numerical simulations we show that spin-controlled VCSELs promise to have superior properties to conventional devices such as threshold reduction, spin control of the emission, or even much faster dynamics. Possible concepts for room-temperature electrical spin injection without large external magnetic fields are summarized, and the progress on the field of purely electrically pumped spin-VCSELs is reviewed. 1. Introduction Concepts for the use of the electron spin as an information carrier have become an important research field called ˇ°spintronics.ˇ± The goal of spintronic research is to exploit the carrier spin degree of freedom additionally to the charge degree of freedom in order to develop novel devices, which offer new functionalities or a better performance as their conventional counterparts. Semiconductor spintronics in general includes the search for alternative device concepts as well as the investigation of the fundamental physical processes as spin injection, spin transport, spin manipulation, and spin detection. This research area was strongly stimulated by the suggestion of the so-called spin transistor by Datta and Das in 1990 [1]. Although such a spin transistor has yet to be realized even about 20 years after its suggestion, a lot of progress has been made in terms of understanding the above-mentioned fundamental physical processes. Moreover, new spintronic device concepts have been developed which might have a more realistic application perspective than the spin transistor. For example, spin-optoelectronic devices might be very promising. In such devices the direct connection between carrier spin momentum and photon spin momentum upon radiative recombination will be utilized in order to generate a spin-controlled net circular polarization degree for the light emission. While spin light-emitting diodes (spin-LEDs) are already established tools in order to characterize and optimize electrical spin injection [2¨C9], spin controlled semiconductor lasers (spin-lasers) seem to be more promising for mass applications. Spin-lasers might provide properties superior to those of their conventional counterparts. For
%U http://www.hindawi.com/journals/aot/2012/268949/