Theoretical analysis and characterization of injection current distribution and influences on optical near-field modes in gain-guided vertical-cavity surface-emitting lasers

Three-dimensional analytical model for analyzing injection current vectors in gain-guided vertical-cavity surface-emitting lasers was developed based on the theory of steady-state electric field. Our calculation covered the spatial distribution of injected current density and its correlation with parameters of the top electric contact ring. The results showed that there exists a region between the two contacts where the radial carrier distribution has a maximum at the center. As the optical power is proportional to the injected current, to obtain fundamental mode or uniform light intensity output with low threshold, the active region should be set to overlap with the boundary layer where the uniform carrier distribution just occurs. The carrier distributions for top-and bottom-emitting configurations with various ring parameters as well as the influences on the near-field modes were discussed.