Numerical investigation of side emission from large-area vertical-cavity surface-emitting lasers.

For large-area ion-implanted vertical-cavity surface-emitting lasers (VCSELs), side emission from the edges of a chip disturbs the laser emission of a VCSEL mode, and suppression of it is fundamental. In this paper, we present results of a numerical investigation of the side emission from large-area VCSELs. We have modeled a VCSEL structure by an infinitely broad layer structure with mirror loss at the edge surfaces. Estimated threshold gains indicate that laser emission occurs either in a VCSEL mode or in an edge-emitting Fabry-Perot (EEFP) mode. Calculated emitter length dependence of the threshold gain of these modes shows good agreement with experimental results, and the side emission is verified to be the laser emission of the EEFP mode. We have also discussed the way to suppress the side emission and confirmed that our recent achievement of over 200 W quasi-continuous-wave output from an ion-implanted VCSEL array is due to antireflection coatings of the edges and introduction of optical losses in ex-emitter regions.