Coherent polarization stabilization in large-aperture rectangular post bottom-emitting vertical-cavity surface-emitting lasers

The output characteristics of large-aperture rectangular post bottom-emitting vertical-cavity surface-emitting lasers (VCSELs) were investigated. It was shown that the output power of the rectangle VCSELs can be up to 660mW at a current of 5A. Both H-polarization (horizontal) and V-polarization (vertical) demonstrated a coherent stabilization over the entire range of operation current, and coherent spectrum blue-shift of H-polarization light occurred with respect to V-polarization light at three different injected currents. The polarization states of output light were stabilized in the two orthogonal directions and H-polarization was the most principal polarization which was parallel to the longer side of the rectangular aperture. From the relationship between polarization ratio and aspect ratio of the oxidation confinement aperture (OCA), it was found that the highest polarization ratio (about 2:1) took place when the appropriate aspect ratio was 5:3, which meant better polarization stabilization in large-aperture VCSELs. ► The polarization states of output light were stabilized in the horizontal and vertical directions. ► Horizontal polarization was the most principal polarization which was parallel to the longer side of the rectangular aperture. ► Both horizontal polarization and vertical polarization demonstrated coherent stabilization over the entire range of operation current. ► Coherent spectrum blue-shift of horizontal polarization light occurred with respect to vertical polarization light at three different injected currents.