Switching of Lasing Circular Polarizations in a (110)-VCSEL

We discuss our demonstration of gigahertz switching of lasing circular polarizations in a (110) GaAs-based vertical-cavity surface-emitting laser (VCSEL) obtained by optical spin injection. The (110)-VCSEL's significantly longer spin relaxation time (2.8 ns) than its carrier lifetime (0.42 ns) enabled it to consecutively oscillate in orthogonal circular polarizations with a high degree of circular polarization, when the time delay between two optical pump pulses with orthogonal circular polarizations was longer than 1 ns. Rate equation analysis closely reproduced the measured results.