Estimating threshold reduction for spin-injected semiconductor lasers

The magnitude of threshold reduction in a semiconductor laser with electron spin injection is shown to depend on such intrinsic properties of the active region as the dominant recombination mechanism, the ratio of hole-to-electron densities of states, the active-region doping, and the available material gain as well as cavity properties such as the optical loss. The threshold reduction is expected to be greatest when the laser’s active region is undoped, the recombination is strongly dominated by Auger processes, and the threshold gain is low. It can approach a factor of 3.5 for fully spin-polarized electrons in the active region.