Analysis of lateral-mode behavior in broad-area InGaN quantum-well lasers

A wave-optical model that is coupled to a microscopic gain theory is used t o investigate lateral mode behavior in group-iii nitride quantum-well laser s, Beam filamentation due to self-focusing in the gain medium is found to l imit fundamental-mode output to narrow stripe lasers or to operation close to lasing threshold, Differences between nitride and conventional near-infr ared semiconductor lasers arise because of band structure differences, in p articular, the presence of a strong quantum-confined Stark effect in the fo rmer. Increasing mirror reflectivities in plane-plane resonators to reduce lasing threshold current tends to exacerbate the filamentation problem. On the other hand, a negative-branch unstable resonator is found to mitigate f ilament effects, enabling fundamental-mode operation far above threshold in broad-area lasers.