Comparison of vertical-cavity surface-emitting lasers with half-wave cavity spacers confined by single- or double-oxide apertures

Data are presented on vertical-cavity surface-emitting lasers (VCSEL's) laterally confined with either single- or double-oxide apertures in a half-wave cavity spacer. Despite a higher nonradiative recombination rate, double aperture as compared to single-aperture devices show lower threshold current density and higher differential quantum efficiency for smaller optical modes. The advantage of double apertures is attributed to the better optical confinement that results in a reduced lateral diffraction loss.