| Popis: |
We present the investigation of several methods to increase the active diameter of single transverse mode oxideconfined VCSELs in both the 850 and 980nm wavelength regimes. Among the concepts considered are mode in- tensity specific shallow surface etched reliefs, monolithically increased cavity lengths, current confinement matching the fundamental mode intensity distribution and saturable absorbers. All approaches are introduced in theoreticalconsiderations and corresponding measurement results are presented. Additionally, numerical simulations are per-formed to gain an increased understanding of some of the mode selection mechanisms. The considered concepts areevaluated in terms of decrease of the series resistance (for impedance matching/driving reasons) and device lifetime ( as derived from maximum current densities) . The results obtained are also compared to other approaches found inliterature (e. g. metal apertures, photocurrent feedback, Fabry-Perot etalon, half-symmetric cavity) . |
