Low Divergence Coherently Coupled Vertical Cavity Surface Emitting Laser Ring Arrays

We report the theory and experimental verification of a method to reduce beam divergence from coherently-coupled ring arrays photonic crystal vertical cavity surface emitting lasers (VCSELs). The etched into top distributed Bragg reflector defines optically coupled array elements, each which has independent current injection thus gain. Using 2-dimensional complex waveguide model we simulate supermodes 6-element VCSELs. influence crystal, free carrier loss, laser gain, carrier-induced index suppression arising spatially defined gain regions are included in our analysis. Our simulations show latter enables preferred anti-guided with reduced divergence. Optical characterization spectral characteristics 6-ring implanted VCSEL shows that when current-tuned quasi-single mode operation, find angle approaches 2° consistent simulations. This may have advantages for high-brightness applications.