Design considerations for large-aperture single-mode oxide-confined VCSELs

Three-dimensional cold-cavity optical modes of oxide-confined AlGaAs/GaAs VCSELs at 850 nm were simulated taking into account the material dispersion to study dependencies of the lasing modal content upon the thickness of the aperture, its position with respect to the mode standing wave and the separation from the cavity. Positioning the thin aperture layer in the mode nodes to decrease the diffraction at low-index oxidized areas or utilizing the thick aperture and thick low Al-content layers above the aperture to promote the lateral leakage of the transverse higher-order modes allow single-mode laser operation to extend to the aperture diameters as large as 10 μm.