Large spot-size narrow waveguide VCSEL

To obtain a large near-field spot-size (i.e. narrow far-field FWHM), a narrow waveguide design is utilized in edge-emitting lasers to expand the transverse mode. A similar situation was observed for the lateral VCSEL mode for a very small aperture oxide-define waveguide structure. A narrow-waveguide VCSEL design incorporating a separate current confinement aperture is shown schematically. This design then allows one to adjust the optical overlap with the gain region by choosing the current aperture. The device is fabricated by two-step MOCVD growth.