Single-transverse mode, low threshold current vertical-cavity surface-emitting laser

The authors report buried heterostructure (BH) vertical cavity surface emitting lasers (VCSELs) emitting a single TEM/sub 00/ mode with a predetermined polarization and low-threshold currents. A threshold current of 0.8 mA and a record-low threshold-density of 490 A/cm/sup 2/ have been achieved with 8 and 32 mu m diameter lasers, respectively. The VCSEL heterostructure used includes three InGaAs strained quantum wells, and 15 and 20.5 pairs of GaAs-AlAs as the top and bottom Bragg reflectors, respectively, grown by molecular beam epitaxy. The threshold currents of 8, 16, and 32 mu m BH VCSELs are 0.8, 1.2, and 3.5 mA, respectively. Both the 8 and 16 mu m BH VCSELs emit a single TEM/sub 00/ mode up to four to five times threshold. The emission is linearly polarized in a predetermined direction. The stable single-mode behavior is attributed to the combination of index-guiding in the active region and anti-index-guiding in the Bragg reflectors.