Controlling filamentation in broad‐area semiconductor lasers and amplifiers

We show that with the introduction of a new pair of epitaxial layers, sandwiched between the active and cladding regions, self‐defocusing can play an important role in stabilizing the lateral mode in broad‐area semiconductor lasers and amplifiers. Under certain conditions, it can be used to eliminate filamentation and provide a nearly flat mode profile by adjusting the band gap of the new self‐defocusing layers. We discuss the use of a strained multiple‐quantum‐well laser for producing such a stable lateral mode.