Polarization-pinning in substrate emission multi-mode vertical-cavity surface-emitting lasers using deep trenches

Abstract

We investigated the stable polarization-pinning properties of substrate emission InGaAs-based 980 nm multi-mode vertical-cavity surface-emitting lasers (VCSELs). For the multi-mode 40 um diameter aperture VCSELs, we introduced 30 μm wide, 9 μm depth deep trenches that are 15 μm away from the cavity aperture. The VCSELs with trench structure produced higher transverse-electric (TE) polarized light output power, as compared with transverse-magnetic (TM) polarized light output power, namely, the effective TM polarization suppression was realized. These trench-etched VCSELs exhibited a 7.5 dB orthogonal polarization suppression ratio with 16.8 mW of light output power at 60 mA of current injection. The dominant TE polarization distribution was observed in polarization-resolved near-field images of spontaneous and stimulated emission due to the induced strain by the etched trenches.