Beam control and manipulation in vertical-cavity surface-emitting lasers

This paper reviews novel techniques which are used to modify the properties of the optical beam generated by vertical cavity surface emitting laser diodes. The main emphasis within the paper concerns the use of etches applied to the device surface either adjacent to or across its optical aperture. Such etches can be used to modify facet reflectivities sufficiently to pin the optical mode precisely and reduce the onset of higher order modes. In addition, single polarization operation is achieved by using deeper etches placed outside the light emitting region. Using this technique, previously multimode components may be transformed to single mode components with precisely fixed polarization states. The effect of these etches on other lasing properties such as spectral performance and power efficiency is also discussed.