Spin-controlled vertical cavity surface-emitting lasers

The output polarization of an optically pumped InGaAs/GaAs vertical cavity surface-emitting laser (VCSEL) is analyzed at room temperature as a function of the circular input polarization degree. The emission of the VCSEL is unambiguously controlled by the exciting polarization and only 30% of spin-polarized electrons are needed in the active region to generate an output polarization degree of up to 100% at short-pulsed pumping. This testifies that a VCSEL can be used as an effective amplifier for spin information even at room temperature. Measurements with a continuous wave excitation were executed to demonstrate the possibility of spin-amplification by electrical spin-injection in a VCSEL. All measurements were confirmed by a phenomenological spin flip model. Our paper is completed with the introduction of Fe/Tb-Multilayers used for spin injection. These contacts enable spin injection without external magnetic fields, i.e. in remanence. Finally, we suggest a combination of these multilayers with a VCSEL-structure to create the first spin-optoelectronic device working both at room temperature and without external fields.