Spin–orbit coupling effects on the optical gain of strained quantum wires

Abstract

The effects of spin–orbit split-off band on InGaAs/InP strained quantum wire structures are theoretically investigated using 6×6 Luttinger–Kohn Hamiltonian. The strong coupling of spin–orbit split-off band with other states has considerable effects on optical properties. It shows that the peak gains are underestimated for the unstrained and the tensile strained quantum wires in 4×4 Luttinger–Kohn model. The change of the density of states and the dipole moments are the main factors for the inconsistent results between the 4×4 and the 6×6 models in the linear optical gain. In the tensile and the unstrained quantum wire structures, the threshold carrier densities are reduced by spin–orbit coupling. The compressive strained structure has the lowest threshold carrier density and the highest differential gain. As a whole, the differential gain is improved by the spin–orbit coupling effects.