A COMPLETELY SINGLE-MODE AND SINGLE-POLARIZATION VERTICAL-CAVITY SURFACE-EMITTING LASERS GROWN ON GAAS (311)B SUBSTRATE

We realized a completely single-mode and single-polarization 0.98 mu m InGaAs/GaAs vertical-cavity surface emitting laser (VCSEL) grown on a GaAs (311) B substrate. The device operates in a single transverse, l ongitudinal mode and polarization state in the entire tested current r ange. An oxide confinement structure with a nearly square oxide apertu re of 2.5 mu m x 3.0 mu m was formed for transverse mode control. We o btained a side mode suppression ratio of over 35 dB and a polarization mode suppression ratio of over 25 dB between the [(2) over bar 33] an d the [01 (1) over bar] axis modes in the entire driving range. The th reshold voltage and electrical specific resistance are as low as 1.5 V and 1.1 x 10(-4) n cm(-2), respectively One of the tested devices sho ws a record low threshold current of 230 mu A for non-(100) substrates .