Polarization stabilization of vertical-cavity top-surface-emitting lasers by inscription of fine metal-interlaced gratings

The polarization of vertical-cavity top-surface-emitting lasers (VCSELs) is stabilized by inscribing a fine metal-interlaced grating into the topmost λ/4 layer of the distributed Bragg reflector (DBR). In this scheme, thin Al/AuZn films are deposited on the sidewalls of the grating defined by the ion milling technique. These metal films enhance polarization anisotropy of the top DBR. Grating periods of 0.9, 1.2, and 1.5 μm are tested and VCSELs with the 1.2- or 1.5-μm grating show good polarization selectivity over the entire range of operating current. The direction of the dominant polarization is orthogonal to the grating line, and the polarization extinction ratio exceeds 40:1 on the average. This polarization discrimination scheme works well for all sizes of VCSELs tested.