Asymmetric oxide apertures of vertical-cavity surface-emitting lasers fabricated by unsymmetrical wet oxidation and its polarization control

• The VCSELs based on asymmetric confinement by oxide layer itself is an ideal solution to obtain polarization stability. • Theoretical simulations guide the selection of asymmetric oxidation apertures. • The oxidation time influences the asymmetry of oxide aperture. • The asymmetry of oxide aperture influences the state of the emitting mode. Given the high symmetry of vertical-cavity surface-emitting lasers (VCSELs) along their emission axis, these lasers demonstrate intrinsic polarization instability. In this study, we report the anisotropy oxide apertures of VCSEL formed by the unsymmetrical airflow distribution during the wet oxidation process. The polarization directions of VCSELs with anisotropy oxide apertures are well-controlled. VCSELs with oxide apertures of 2 μm × 4.6 μm achieve an orthogonal polarization suppression ratio of more than 20 dB and side-mode suppression ratio of more than 25 dB. In addition, an asymmetric far field distribution is observed, which can be ascribed to the asymmetric oxide apertures.