Room-temperature threshold reduction in vertical-cavity surface-emitting lasers by injection of spin-polarized electrons

We experimentally demonstrate the reduction of the laser threshold of a commercial GaAs∕(AlGa)As vertical-cavity surface-emitting laser (VCSEL) by optical injection of spin-polarized electrons at room temperature. Calculations with a rate-equation model reproduce the measured reduction of 2.5% for injected electrons with 50% spin polarization. The model predicts an improved threshold reduction of 50% in otherwise identical VCSELs grown on a (110) substrate due to the enhanced spin lifetime in such structures.