Control of Light-Output Polarization for Surface-Emitting-Laser Type Device by Strained Active Layer Grown on Misoriented Substrate

We propose and demonstrate control of light-output polarization for surface-emitting laser-type devices by using strained quantum-well active layers grown on a misoriented substrate. This structure has slightly asymmetric strain tensor elements on the surface plane. Due to orbital-strain interaction, the valence band structures change and the optical transition matrix element depends on the polarization of the light. Here, theoretical analysis and experimental results on the direction of misorientation are described, and it is shown that how the polarization of the light-output is related to asymmetry in strain tensors. For the devices, which have In0.2Ga0.8 As active layers grown on a 2-degree-off-(100) GaAs substrate toward (111)B, the light-output is polarized in [011] with the reproducibility of as high as 88%. This highly controlled polarization is probably due to the combination of converse piezoelectric effect and asymmetry in the lattice mismatch on the surface caused by misorientation.